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Hearing Acuity, Background Noise and ADHD by Heather McDonald copyright Heather McDonald Australia 2004 h.mcdonald@optusnet.com.au CHAPTER 1. INTRODUCTION What students hear impacts on what they learnResearchers have repeatedly found that the quantity and quality of what students hear has a major impact on what they learn. Ross states this succinctly: Ross states his surprise when intelligent, committed and sensitive child focused professionals have difficulty with this concept . This apparent enigma regarding the logical relationship between the individuals hearing acuity and the acoustical environment is evident when considering both classroom learning and classroom behaviour. The reason behind this may be because of the "...ambiguous, invisible, underestimated and often unidentified acoustic filter effect of hearing problems" . Flexer argues that the fact that children’s inability to hear in a classroom is underestimated, could be because many children appear to behave in a way that indicates they can hear, however these same children may not be able to hear an intelligible sound - instead they may "...be responding to the intonation patterns rather than to the specifics of an utterance . Flexer reminds us that the inability to hear "well enough" becomes a significant educational problem because mainstream classrooms are auditory-verbal environments: Factors Affecting Classroom Communication There are many factors affecting classroom communication, some of these concern the personal qualities that listeners bring to the classroom and other factors concern the classroom environment. increased difficulty when hearing-against-background-noise.Certain personal qualities will put some children at greater risk of increased difficulty when hearing-against-background-noise. Crandell, Smaldino and Flexer assert that it is well recognised that listeners with sensorineural hearing loss have greater difficulty understanding speech in noise than do normal hearers. However, they also mention that researchers have identified a number of populations of children with ‘normal-hearing sensitivity’ who have also been found to experience greater speech perception difficulties in the classroom environment. These listeners include young children, children with attention problems and: Several environmental factors affect classroom communication. These form part of the classroom acoustics. Included in classroom acoustics is the signal-to-noise ratio (or alternatively referred to as the speech-to-noise ratio), reverberation times and the distance the student is from the signal . Strict structural guidelines regarding acoustical building materials and classroom layout has resulted from research of the effects of classroom noise on learners, with the American Speech-Language-Hearing Association (ASHA) recommending unoccupied classroom noise levels to be equal to or less than 35 dBA. This organisation also recommend that the maximum average reverberation time in unoccupied learning spaces be between 0.4-0.6 of a second. typical classroom noise levels far exceed this ASHA recommended levelCrandell & Smaldino reviewed the literature on average classroom noise levels and found that typical classroom noise levels far exceed this ASHA recommended level with a range from 41-51 dBA.. However, the most important environmental factor that affects classroom communication is the signal-to-noise ratio. The American Speech-Language-Hearing Association recommends a speech to noise ratio (SNR) of at least +15 dB in typical classrooms . Research has found that the range of SNRs for classrooms has been reported to be from -7 dB to +5 dB (Crandell & Smaldino, 2000 p364).
Educational Implications A comprehensive summary of common causes, identification, audiological, behavioural, communicative and educational symptoms and various interventions are detailed in appendix A. However Table 1.1 below, provides a short summary of what researchers have found.
Table 1.1 Educational Implications for children who have difficulty hearing against background noise
Children who cannot hear clearly, for whatever reason, may react to this by actively tuning out the distracting and confusing stimuli.As can be seen from the above table links have been made between children’s inattentive behaviour and classroom noise. Children who cannot hear clearly, for whatever reason, may react to this by actively tuning out the distracting and confusing stimuli. Mussen makes the observation that "the effort of listening to half-heard signals is always great. The...child with partial hearing may not expend the energy required to attend selectively". learned inattentiveness to soundOther researchers have postulated that one of the possible consequences of fluctuating hearing loss in children is a "learned inattentiveness to sound" . Smaldino and Crandell suggest that The relationship between hearing and attention deficit disorder has been made by some audiologists and ‘sound’ therapists . Table 1.2 below (Phonic Ear, 1996) reveals the behavioural similarities between mild hearing loss and Attention Deficit Disorder. With such similarities it is possible that some children are being misdiagnosed. However, I could not locate any research that specifically tested this hypothesis.
Table 1.2 Similarities between Mild Hearing Loss and Attention Deficit Disorder
Detection of Hearing Acuity Against Background Noise Current standard audiological assessments are conducted by either an audiologist or an audiometrist. They are conducted in sound proof rooms using air conduction and pure tones at different frequencies against a background of silence. The clinician may also test bone conduction, and speech stimuli in silence . Typically the frequencies measured are 500, 1000, 2000, 4000 and 8000 Hertz. Frequencies are a measure of the pitch or how high or low the sound is. The intensity of the sound is the loudness. This is measured in decibels (dB). The more decibels, the louder the sound . pure-tone hearing assessments provide limited useful dataThere is a growing body of research that provides evidence that pure-tone hearing assessments provide limited useful data regarding a child’s ability to listen in a classroom situation. As the following quote by Flexer states, many of the conditions that predispose children to having great difficulty hearing in a normal classroom situation remain undetected due to the problems with standard audiometry:
Once a hearing loss is detected the labels normal, minimal or mild are allocated to describe the severity of the loss. These labels can be misleading, as they are often used by different audiologists and researchers to describe different hearing levels. An example is provided in table 1.3 below.. This table demonstrates three slightly different classification schedules for children’s hearing. Table 1.3 Children’s Hearing Sensitivity Classification
pure-tone tests in silence been questioned.In addition to the lack of uniformity of the labels used to describe hearing levels, the reliability of pure-tone tests in silence have also been questioned. Murray made the following comment to the Standing Committee on Employment, Education and Workplace Relations on the Education Of Boys: There are many audiologists and researchers who question the validity of the use of the pure-tone audiogram for assessing real life listening situations. This is because the audiogram provides no information on the quality of audition present at these levels; it merely indicates the dividing line between hearing and not hearing . Flexer (1994,p 36) states thatA child may appear to hear well in a soundproof audiological test room or a quiet one-to-one communicative situation, but not hear equally well in a relatively noisy home or school setting.Auditory System analyses the complex sound waves arising from this ‘noisePlomp , questions the validity of the physics behind testing ‘pure tones in silence’. He notes that there is no such thing as pure-tones in real life listening. The auditory system usually operates in noise and that one of its main functions is to analyse the complex sound waves arising from this ‘noise’. Plomp states that processes involved in the perception and analysis of such complex mixtures cannot be revealed by the study of simple stimuli under silent and unimodal conditions. Plomp proposes that this "microscopic" approach has provided interesting but also inaccurate results and needs to be combined with the "macroscopic" information gathered by more ‘realistic’ hearing indicators. otitis media with effusion before their first birthday,Other studies have found that pure tone tests overlook children who have difficulty hearing against background noise. Gravel, Wallace and Ruben (1996) have found that children who experienced otitis media with effusion before their first birthday, had greater difficulty hearing against background noise than children who did not suffer otitis media with effusion at such a young age, and yet they found no differences between the groups when tested on the audiological pure tone tests. Fatigue not includedHicks and Tharpe (2002) point out that even hearing assessments that test word recognition against background noise, a more valid test of educational hearing ability than pure-tone tests, fail to capture the children who fatigue in the process of listening. Therefore, any currently used hearing assessments will miss many of the children who need a better signal-to-noise ratio in order to reduce fatigue. boys process speech sounds more slowlyIn addition recent research undertaken at National Acoustic Laboratories (NAL) using otoacoustic emissions indicates that from the age of four years, boys have significantly reduced physiological capacity to process auditory ‘streams’ of sound such as speech. That is, compared with girls, boys process speech sounds more slowly . It is evident from this research that otoacoustic emissions provide a more sensitive assessment of hearing than pure-tone tests. Considering the above criticisms, and the fact that it is well established that standard audiometry procedures using pure tone tests do not test for hearing acuity against background noise , raises the question of how this ‘real life’ listening ability is tested and who conducts these tests and who has access to this assessment. central auditory functionThe ability to hear against background noise has been considered a central auditory function rather than a sensory function, thus audiologists who assess central auditory processing deficits use some specific tests for this purpose. Ferre and Bellis include the detection of children with difficulty hearing against background noise as part of their Central Auditory Processing Disorder (CAPD) testing battery. Central Auditory Processing tests are used to test children thought to have difficulty understanding the meaning of incoming sounds Central auditory processing is not considered an impairment of hearing reception or reduced hearing sensitivity, as children are screened so that only the children with ‘normal’ hearing sensitivity are given CAPD tests. This means that in current practice a child is only screened for their ability to hear-against-background-noise when they have a CAPD test. This anomaly between the availability of standard audiological testing compared to the more ‘realistic’ (and therefore more informative) tests of hearing ability formed part of the motivation for conducting the present study. question the validity of audiological results in regard to their valid extrapolation into the students educational environment.The present study was undertaken due to my interest in the controversies, mentioned above, surrounding audiological tests, classroom acoustics and the hearing abilities each individual brings to the classroom. My initial interest was stimulated from the experience of my son, whom was 6 years old and in Grade 1, when he was described by his teacher as underachieving academically. In addition to other observations, his teacher complained that when the whole class was given instructions, he would wait for other students to get the right books for him, and to tell him what to do. During the following 10 months, I had the opportunity to witness seven different audiological assessments. These experiences led me to question the validity of the audiological procedures, including the subjectivity of the audiological examination and the use of the ‘pure-tone’ test in silence as the adjudicator of ‘hearing ability’. In particular this led me to question the validity of audiological results in regard to their valid extrapolation into the students educational environment. Through my studies in Literacy, I learned of the Goldman-Fristoe-Woodcock Test of Auditory Discrimination (1970) (G-F-W), which did not require an audiologist to assess hearing acuity against background noise. Aims and purposes The aims and purposes of this study were to find out how many children in grades one and two of a typical Australian primary school, have difficulty hearing against background noise, and to determine if there were any behavioural effects of this difficulty as perceived by their teachers and parent(s)/caregiver(s). A further aim was to find out how much noise was generated in these classrooms during a normal school day during various activities. The research setting The research was conducted in a metropolitan state primary school in Adelaide. The school is situated in a lower socio-economic suburb. The 103 students who participated in this study were in either Grade 1 or 2. The age and ‘English-as-a-second language’ status was provided by the primary school, all other data came from the children, parent(s)/caregiver(s) or where applicable the teachers.
The Research Questions The first major research question was to determine the percentage of children in an ordinary school population who, after at least one or more years of schooling, have difficulty hearing against background noise. The second major research question was whether there was a relationship between a child’s hearing acuity against background noise, and their classroom behaviours as perceived by their teachers. The third research question was whether there was a relationship between a child’s hearing acuity against background noise, and their behaviours at home as noticed by their parent(s)/caregiver(s). The fourth research question was to determine the levels of background noise Australian school children were exposed to during various classroom activities. CHAPTER 2 RESEARCH METHOD PARTICIPANTS The participants were obtained from a school population which was selected from a lower socio-economic area of Adelaide. There was a possible population of 127 children enrolled in grade 1 and 2 at this school, with all 127 given the opportunity to participate, through an addressed package to the parent(s)/caregiver(s) of each child. Contained in this package (see appendix B) were two letters of introduction about the study along with the parent(s)/caregiver(s) questionnaire and consent form. An initial total of 65 completed questionnaires and consent forms were returned within a few weeks of the initial ‘distribution’. A second distribution of the same package was sent in the same manner to the remaining 64 children and a further 39 children returned their consent forms and the completed parent(s)/caregiver(s) questionnaire. By the end of the study 103 children were administered the Goldman-Fristoe-Woodcock Test of Auditory Discrimination.This method of sampling is considered an opportunity sample, however as the sample came from the whole school population of grade 1 and 2 children, extrapolation to other similar populations could be valid. There were no significant differences in the gender breakdown of the participants with 49% being female and 51% male. Year One students comprised 54% of the participants with the remaining 46% being Year Two students. Ninety-three percent of the participants were aged between 6 years and 7 years 11 months. Students for whom English is a second language (ESL), comprised only 9% of the participants.
TEST INSTRUMENTS Parent(s)/caregiver(s) Questionnaire The parent(s)/caregiver(s) Questionnaire (appendix B) was developed by the researcher in consultation with my supervisor. Due to the time constraint of the Honours year, including the need to get multiple ethic committee’s approval for the use of the test instruments, the items were prepared after a preliminary survey of the literature on hearing loss, and central auditory processing deficits. The questionnaire was divided into two sections, one on the incidence of hearing tests, hearing problems, speech or language difficulties, colds, ear infections, and whether the child had ever had a grommit placed in the ear. The second part of the questionnaire was a behavioural survey - labelled Listening. This section included 7 questions and originally employed a three point scale – Occasionally, Sometimes and Constantly. Once the data had been collected an alpha test was conducted which indicated that internal consistency was high suggesting that all items were measuring a common domain. The items were found to be internally consistent with an overall alpha value of .6962 . By removing the question about Play, the alpha increased to .7342 . Test-retest reliability, construct and criterion validity of the measurements were not tested due to time constraints – however these could be tested in future studies.
Teacher Questionnaire The teacher questionnaire (appendix B) was designed by the researcher in consultation with my supervisor. Due to the time constraint of the Honours year, including the need to get multiple ethic committee’s approval for the use of the test instruments, the items were made up after only a preliminary survey of the literature on hearing loss. Many of the items are similar to those in Berry which provides teacher tips for identifying a possible hearing impaired child. One of the notable exceptions is that Berry did not mention the mispronunciation of words as an indicator. Once the data had been collected an alpha test (see appendix C) was conducted which indicated that internal consistency was high with an alpha value of .863, suggesting that all items were measuring a common domain. S.I.F.T.\E.R.Subsequent to the development and implementation of the questionnaire an instrument called the S.I.F.T.E.R. has been located which was developed for teachers to use and was designed "...to sift out students who are educationally at risk possibly as a result of hearing problems." There are 15 items on the S.I.F.T.E.R instrument which are divided into five areas with 3 questions relating to each area. The five areas include: academics, attention, communication, class behaviour and school behaviour. Five Items on the fifteen item S.I.F.T.E.R are very similar to six of the items on the teacher questionnaire developed for this study. They include:
Table 2.1Similarities between the S.I.F.T.E.R Questionnaire and the Teacher Questionnaire
The S.I.F.T.E.R instrument has a five point scale, whereas the teacher questionnaire used a four point scale of never, occasionally, often and always. The additional behavioural items on the questionnaire developed for this study may have provided more precise information about the existence of a hearing problem – especially as the S.I.F.T.E.R. did not have an item regarding the mispronunciation of words. In addition academic results were deliberately left out of the present questionnaire as these can be caused by a multitude of factors (especially at this young age) and therefore could have confounded the data.
Goldman-Fristoe-Woodcock Test of Auditory Discrimination The Goldman-Fristoe-Woodcock Test of Auditory Discrimination (G-F-W) was used in the present research project because of its design, construct validity, concurrent validity, internal-consistency, and test-retest reliability as purported in their manual that comes with the test (Goldman et al, 1970; pp15-31). Another reason for using this test was because it has been reported to be used extensively with children aged 4 years and over . Because of the tests design, the authors state that Controlling for factors other than auditory discrimination is a major concern for test developers, and the G-F-W (Goldman et al.,1970, p 7) test minimizes these by: Thus it is expected that the use of the G-F-W was a valid and appropriate test to use with the present research sample because it was designed and normed against children of this age, and because it uses a pictorial presentation, requires the respondent to only point which eliminates an articulation variable and incorporates the use of a training procedure which moderates any special problems that may arise form unfamiliarity with any of the pictures .
Equipment A standard tape player was used (Panasonic RX-FS430) without earphones. This was acceptable as the room was quiet. The G-F-W test manual recommends the use of high quality ear phones, however they state that it is also acceptable to use a speaker without any significant degradation of performance on the Noise Subtest, and it may result "...in somewhat poorer performance on the quiet subtest" (Goldman et al.,1970 p 10). The volume control of the tape player was set at a comfortable level of loudness. It was calibrated to a level of 65 dBA as suggested (Goldman et al., 1970 p .12) using a Sound Level Meter and the calibration tone provided on the G-F-W pre-recorded tape.
DESIGN Parent(s)/caregiver(s) were requested to agree to their child/rens participation in this study, and at the same time they were requested to complete a questionnaire about their child/ren(s) aural health history and ‘hearing’ behaviours. Out of a possible population of 127 children, 103 parents consented and returned the questionnaire. The seven classroom teachers were requested to complete a questionnaire for 65 of these children. It was decided at the inception of the study to limit the number questionnaires for the teachers to complete. This was to ensure that the teachers would not be overtaxed with work, and therefore be able to give more energy to the completion of the questionnaires that they were given. To approximate a random selection the teachers completed the questionnaires for all of the children whom had returned their questionnaire and approval form by the end of week 7 of Term 2. The teachers completed this task by the end of week 9, Term 2. In order to check for any bias in the group that was selected for the teacher questionnaire, a Chi Square analysis was completed on various attributes (see appendix E). There were no significant differences between the group of children who were selected to be reported on by the teachers and the children who were not reported on, in any of the attributes assessed e.g. difficulty hearing against background noise, whether they had ever had their hearing tested or had reported hearing or speech-language problems or number of ear infections. The only category that approached significance was gender with slightly more girls being represented than boys (55% girls and 45% boys; Χ2 = 3.3, df=1, p= .07)The testing procedure Students were taken from their class one at a time, and brought to a small open room at the side of the staff room. The staff room wasn’t in use during the testing and therefore the testing was done in quiet conditions. Most of the testing was conducted between 9.30am and 1pm, with only a small number of students tested between 1:45 and 2.15pm. This was partly due to concern that students could be affected by the time of day with students tested in the afternoon being more fatigued than the students tested in the morning. After suitable rapport was gained with the student, the training procedure was started. This took about 8 minutes per student to complete. As instructed in the G-F-W manual, the students were given as much training as they required before testing (Goldman et al., 1970 p 9). Most children sped through this section as they understood all the vocabulary used. A small number of the younger children needed the ‘shack’, ‘cab’, and ‘tack’ word/picture associations to be trained. They all achieved mastery before starting the subtests. Upon completion of the Training Procedure, the testing procedure was begun. The entire test procedure took 7½ minutes once the tape had been started. The Quiet Subtest was given first, with the instructions given to the child via the tape: After the 30 items were tested on the Quiet Subtest, the Noise Subtest commenced. Every child appeared to be listening carefully and trying hard-with many children leaning towards the sound source to ‘hear better’. After completion each child was asked what they thought of it and most said that it was ‘fun’ while others felt it was ‘a bit hard’ and some ‘easy’. At the completion the student could choose a sticker and was then asked to collect the next student from their class. Scoring Scoring was done by recording the number of errors on the response form (see appendix D). When a participant was unable to make a choice on a given test plate the examiner left the appropriate space on the response form blank and this was counted as an error in accordance with the manual procedures (Goldman et al., 1970 p 13).
Interpretation The norms from appendix C were used for the present study as these are recommended by the authors to "...be of most use in research applications" (Goldman et al. 1970 p 14). They state that: The data was analysed using two cutting scores as recommended by the authors: As auditory discrimination improves with age, children of different ages required a different number of errors in order to be classified as having an auditory discrimination difficulty. Table 2.2 shows how many errors were needed in order to be included in the group of children who had difficulty discriminating words against background noise (30th percentile) and those children with substantial difficulty discriminating words against background noise (the 20th percentile). Each subtest had a possible score of 30.
Table 2.2 Number of Errors required to be classified as having Difficulty and Substantial Difficulty Discriminating Words Against Background Noise.
The following table (Table 2.3) shows how many errors were needed in order to be classified as having difficulty discriminating words in quiet at both the 30th and 20th percentile. Each subtest had a possible score of 30. Table 2.3 Number of Errors required to be classified as having Difficulty Discriminating Words in quiet conditions at the 20th and 30th percentiles.
Reporting to the parent(s)/caregiver(s) The percentile scores used to report to the parent(s)/caregiver(s) were the ones recommended "For General Use" by the G-F-W manual . The raw scores were converted to Percentile Scores To Upper Limit Of Score Intervals as per the norms presented in Appendix E (Goldman et al. 1970 p 30-31). Parent(s)/caregiver(s) were given general information about hearing and classroom acoustics. Parent(s)/caregiver(s) of children with significant difficulties as detected within this current study, were offered specific advice.
Sound Level Measurements A sound level measure (SLM) instrument Type 2 with an A rating and slow response, was used to determine the sound level measurement of the seven classrooms. The procedures advised by Crandell and Smaldino were followed. Readings were taken at various points within the seven classrooms, when the teachers were reading a standard book passage to the children, and in ‘silence’, both with and without air conditioning systems on. SLM’s were also taken when classes were involved in small group activities.
DATA ANALYSIS The raw scores from the G-F-W were converted to the percentile scores. These percentile scores were then analysed using frequencies to determine the number of children with difficulty discriminating words against background noise. The percentile scores were then recoded to group all of the scores into two nominal groups -those children with a percentile score of 31 or more (coded with a 1) and those children with a percentile of 30 and below (coded with a 2). These groups were labelled "Children without difficulty hearing against background noise/Children with difficulty hearing against background noise". The percentile scores were recoded a second time to group all of the scores into two different nominal groups – those children with a percentile score of 21 or more (coded with a 1) and those children with a percentile of 20 and below (coded with a 2). This coding gave the categories of "Children without substantial difficulty hearing against background noise/ Children with substantial difficulty hearing against background noise". Frequencies were also obtained for the data gathered from the teacher and parent(s)/caregiver(s) questionnaire. The coding scheme is detailed in appendix B.Chi Square (Χ 2 ) Tests were used to determine the relationship between the various nominal data categories. Due to the restrictions in the use of the Χ2 test , when the data was computed to have one degree of freedom (df) and the expected frequency in any of the cells were less than 5 or when there were more than 1 df and the expected frequency in more than 20% of the cells was less than 5, the Fisher’s exact test statistic was reported . Most of the statistics reported were for two–tailed tests, however if the one-tailed result was reported this was indicated.Teacher responses and parent/caregiver responses each had four categories that the respondents could mark. However there were too few responses in some of the categories to compute the Chi Square statistic, so the data was combined and recoded. The teacher questionnaire categories Never and Occasionally were combined as was Often and Always. On the parent(s)/caregiver(s) questionnaire the response categories to the questions asked under Listening were combined – No and Occasionally were combined and Sometimes and Constantly were combined.
CHAPTER 3 RESULTS Research Question 1 What percentage of children in an ordinary school population who, after at least one or more years of schooling, have difficulty hearing against background noise? . Seventy percent of the sample had difficulty hearing against background noise, and 38 percent had substantial difficulty hearing against background noise as noted in table 3.1 below. Table 3.1 Results of the Goldman-Fristoe-Woodcox Test of Auditory Discrimination – Noise subtest
There were no statistically significant gender differences and difficulty discriminating words against background noise. Testing word discrimination against ‘silence’ was included as the first subtest after the training procedure. The results are described in table 3.2.
Table 3.2 Results of the Goldman-Fristoe-Woodcox Test of Auditory Discrimination – Quiet subtest
Research question 2. Is there a relationship between a child’s hearing acuity against background noise, and their classroom behaviours as perceived by their teachers? The results of Chi Square tests showed a statistically significant relationship was found between several of the behaviours as perceived by the classroom teachers, and the children with substantial difficulty hearing against background noise. The results pertaining to this group of children are in Table 3.3 below. The relationship between the questionnaire items and the DSM-IV classification of ADHD-Inattentive Subtype is included in the table and a ü is entered where an item could be classified as a behaviour that is classified as ADHD-I behaviour.
Table 3.3 Results of the Chi Square Test between the Teacher Questionnaire results and Children with SUBSTANTIAL difficulty hearing against background noise- the relationship between these behaviours and the DSM-IV Classification of ADHD-I subtype.
a Fisher’s Exact Test (2 sided)b Fisher’s Exact Test (1 sided)
Research Question 3. Is there a relationship between a child’s hearing acuity against background noise, and their behaviours at home as noticed by their parents? Two of the Listening questions approached statistical significance, these are referred to in Table 3.4 below. Parents reported that they spoke louder ( Χ2 = 2.48, df=1, p= .09); and that they speak more slowly (Χ2 = 2.03, df=1, p= .11) to children who had substantial difficulty hearing against background noise.Table 3.4 Chi Square results between parent(s)/caregiver(s) questionnaire and children who have substantial difficulty hearing against background noise
b Fisher’s Exact Test (1 sided)
Table 3.5 Descriptive statistics from the Parent(s)/Caregiver(s) Questionnaire and Chi Square results between parent(s)/caregiver(s) questionnaire and children who had substantial difficulty hearing against background noise
Two of the above items on the parent(s)/caregiver(s) Questionnaire were found to be statistically significant. The children who had substantial difficulty hearing against background noise were reported to have a speech or language difficulty (Χ2 = 4.98, df=1, p= .03) and they were more likely to have been to a speech pathologist (Χ2 = 4.31, df=1, p= .04).
Research Question 4. The fourth research question was to determine the levels of background noise Australian school children were exposed to during various classroom activities. As can be seen from table 3.6 below the children were exposed to variable noise levels depending on the activity and whether the airconditioning system was operating. In all conditions it is evident that the noise levels were high compared to the levels recommended by the American Speech-Language Association .
Table 3.6 Sound level Measurements during various classroom activities
Incidental results Class Effects It is evident from the data in table 3.7, that some teachers have a far greater number of children with auditory discrimination problems than other teachers.
Table 3.7 Class analysis of the Percentage of children tested who had substantial difficulty discriminating words against background noise
CHAPTER 4
DISCUSSION AND CONCLUSIONS
Research Question 1 What percentage of children in an ordinary school population who, after at least one or more years of schooling, have difficulty hearing against background noise? The present study has found that the vast majority (70%) of the school children tested have difficulty, and 38% of the school children in this study, have substantial difficulty discriminating words against background noise. Although the present study involved a relatively small sample of 103 children, the results could be reflective of the general population as they are similar to those found by other researchers. For example these results are similar to the incidence of minimal hearing loss found by the Mainstream Amplification Resource Room Study (MARRS). This was a three year, longitudinal study of students possessing a minimal hearing loss (greater than 10 dB hearing level and less than 40 dB hearing level) and academic achievement deficits . The MARRS study, which involved a population of more than 1300 students over three years, found that 32% of the students in regular classrooms at the 4th , 5th and 6th grades were found to have a minimal hearing loss. The MARRS study tested hearing against pure tones in silence to find the incidence of 32% of children with minimal hearing loss, whereas the present study was concerned with one of the consequences of minimal hearing loss i.e. difficulty hearing against background noise . Apart from the MARRS project, It is difficult to obtain reliable figures on the incidence of hearing loss as many studies have design flaws. For example Flexer comments on a study which tested the hearing of 38,000 school children in the US. Flexer states: There has been some Australian research that has found that junior primary children have a high incidence of fluctuating conductive hearing loss with up to 30% on any given day suffering from this condition . As the present study was investigating hearing acuity against background noise, the results of the quiet subtest was not of primary concern. However these results are worthy of comment. As can be seen in Table 3.1 and Table 3.2 it is evident that almost the same percentage of children had ‘substantial difficulty" on the quiet subtest as well as on the noise subtest. This is initially quite surprising as from previous research we would expect more children to have problems discriminating words against background noise rather than in quiet conditions. No relationships were found between the children within this ‘quiet’ group and the teacher behaviour ratings. Thus, this result required further investigation. The reasons this study produced a large number of children with substantial difficulty discriminating words in quiet could be because: (a) the majority of these children only needed to make 3 or 4 errors to be included in this substantial difficulty in quiet group whereas they required between 13 and 14 errors under the noise conditions (see Tables 2.2 and 2.3). (b) the absence of headphones meant that the testing conditions were not ideal for the quiet subtest which may have resulted "...in somewhat poorer performance on the quiet subtest" (Goldman et al.,1970 p 10); (c) many of the children could have had a conductive hearing loss on the day as testing was completed during winter and many had colds which could be different to when the normative sample was collected-however this information is not available (d) the G-F-W normative sample was small and obtained over 30 years ago in the US, thus these norms for the quiet subtest could be unsuitable to apply to Australian children. The development of Australian norms could eliminate this problem. The comment by Rowe and Rowe in their supplement to the Inquiry into the Education of Boys that the "…teacher effects far outweigh other variables [for educational outcomes]" prompted me to test if there were any differences in the numbers of children who had substantial difficulty hearing-against-background-noise between the seven classes. The data in Table 3.7 shows that some teachers had more than 50% (58% and 64%) of their children (who were tested) substantially affected, whereas other teachers only had 15% and 18% of their tested children substantially affected by background noise. Having a large number of children with this difficulty in one class could impose quite difficult teaching conditions -especially if the teacher was unaware as to why the children were behaving in particular ways – for example these children may require instructions repeated more often than other children; they could be easily distracted; and seek the guidance of others more often than children without this auditory problem.
Gender The present study did not find any statistically significant gender differences. Previous research has found that boys tend to incur more hearing damage than girls during their pre-teen and teenage years due to their lifestyle choices (e.g. noisy toys such as cap guns) and in particular their use of personal stereo’s , nonetheless as these children were in grade 1 and 2 these lifestyle choices may not have had any discernable effects yet. However taking into consideration the recent research undertaken at National Acoustic Laboratories (NAL) mentioned in Chapter 1, which indicate that from the age of four years, boys (on average) process speech at a slower rate than girls , gender differences could have been expected to show up in this study. One possible reason that the present study failed to find statistically significant gender differences such as found by NAL, could be because the G-F-W test is very slowly paced. The items are spoken at slower than conversational speed, which means that speed of processing is not a confounding factor in this test. Although this feature aids in determining those who have difficulty discriminating words against noise, this also reduces the G-F-W’s validity for assessing ‘real life’ listening. It is also well established that boys are over represented within the ADHD population , as well as constituting the majority of Central Auditory Processing difficulties (CAPD) . A logical extrapolation from this data, could be that boys slower processing of speech could combine with other hearing problems such as minimal hearing loss or hearing-against-background-noise difficulty and compound these problems to such a degree that they are being detected in their ‘real world’ environment – as ADHD or CAPD. Whereas girls ability to process language faster could reduce the effect of either minimal hearing loss or difficulty hearing-against-background-noise to such an extent that these problems are not being detected in their ‘real world’ environments – girls may merely be ‘failing to reach their academic potential’ which may go unnoticed. This could be one of the reasons why there are such striking gender differences in these areas - future research could focus on these factors using ‘realistic’ hearing tests-which will be discussed later in this chapter.
Research question 2. Is there a relationship between a child’s hearing acuity against background noise, and their classroom behaviours as perceived by their teachers? Statistically significant relationships were found between the group of children that had substantial difficulty hearing-against-background-noise and many of their classroom behaviours as perceived by their teachers. From this data it is evident that children with substantial difficulty hearing-against-background-noise are less likely to contribute to class discussions (p<.05); are more likely to mispronounce words (p<.05); are more easily distracted during class activities (p<.05), are more likely to seek guidance from others (p<.05) and also need instructions repeated more often (p<.05) than children not as affected by background noise. Although not statistically significant there was also a strong trend to describe these children as – more likely to wait and observe what others are doing before starting (p=.08), and they were more likely to need to be reminded about what to do (p=.11). Even taking into account the present design limitations (e.g. small sample size, small number of teachers) the relationships found in the present study between auditory discrimination ability and classroom behaviour are noteworthy and may be representative of the wider population of children with difficulties hearing against background noise. These results reveal that teachers are observing behaviours that could be considered "inattentive" (see table 3.3). This raises many questions for example : (a) what causes this inattentive behaviour? (b) what effect do inattentive behaviours have on the educational outcomes of the students behaving that way? (c) how can this behaviour be changed into more productive attentive behaviour? (d) what happens in the classroom when these inattentive behaviours are observed by the teacher? (e) what effect does having children who exhibit these inattentive behaviours have on the teacher and other students? Some of these questions will be discussed later in this chapter.
Research Question 3. Is there a relationship between a child’s hearing acuity against background noise, and their behaviours at home as noticed by their parents/caregivers? Two of the most significant results derived from the parent(s)/caregiver(s) questionnaire, revealed that the children with the greatest difficulty discriminating words-against-background-noise were much more likely to have speech language difficulties (p<.05) and were more likely to have been to a speech/language pathologist (p<.05). These parent(s)/caregiver(s) reports concur with the teachers reports that children substantially affected by background noise are more likely to mispronounce words.The possibility that children with speech-language difficulties have hearing difficulties is known to speech pathologists however when the children are sent for an audiological assessment, they are often not being identified as having a hearing problem. Meyer writes about the identification and education of the ‘hard of hearing child’ and states: "Some of these children may have had years of speech therapy without being identified as hard of hearing". A possible reason for this failure to identify children with hearing loss could be due to the inherent limitations in standard pure-tone audiometry assessments- as outlined in chapter 1. These include the subjectivity of the assessments and also the problem with the different classification schemes used by different audiologists that lead them to ‘determine’ whether a child has a ‘hearing impairment’. In addition many audiologists and audiometrists seem unaware that even minimal hearing loss (15 - 25 dB HL) combined with poor classroom acoustics, has such a huge impact on the educational attainments of children and therefore on their subsequent life opportunities e.g. the MARRS study mentioned earlier, found that 75% of children with learning difficulties had a minimal hearing loss . It seems evident from this present study that parent(s)/caregiver(s) were unable to detect the children who had substantial difficulty hearing against background noise with only 8% reporting that their child had "poor" hearing compared to the 38% who demonstrated this condition. In addition none of the Chi Square tests between the ’listening behaviour’ items on the parent(s)/caregiver(s) questionnaire and the results of the child’s hearing acuity-against-background-noise reached statistical significance, although there was a trend towards parents stating that they spoke louder to the children who were found to have the greatest difficulty discriminating words against background noise (p=.09); and they reported that they more frequently spoke slowly to this group of children (p=.11).These results are consistent with research that has found that parents cannot detect mild hearing loss in their children . This phenomenon is perhaps due to what Flexer calls the "...ambiguous, invisible, underestimated and often unidentified acoustic filter effect of hearing problems" . From the results obtained in the present study, it could be recommended that children with speech-language difficulties be routinely tested for their hearing acuity-against-background-noise – as this is the milieu where they ‘hear’ most speech. Perhaps it is even possible to speculate that one of the factors contributing to their speech impediment is poor classroom acoustics which influences how they are actually hearing the speech sounds: This could be what Flexer was alluding to when she stated that: Thus, educators need to be aware that children who mispronounce words (more than is developmentally appropriate) may have an educationally significant hearing impairment and difficulty hearing-against-background-noise. One of the interesting results of the parent(s)/caregiver(s) questionnaire was that 75% of the children had had their hearing tested with only 8% reportedly having ‘poor’ results - but none of these children had any assistive hearing devices nor were the teachers informed about their hearing ‘condition’, which means they could not provide any compensatory strategies for these children with "poor" hearing. This could indicate that standard audiometric testing failed to find the children who had substantial difficulty-hearing-against-background-noise. However, there are design limitations that may affect the generalisability of this data. For instance the present research data on standard audiometric testing is based on parent(s)/caregiver(s) reports of tests that were done in the past, and the audiograms were not sighted by the researcher. Future studies could include pure-tone assessments to be tested at the same time as more ‘realistic’ hearing tests as part of the research design to clarify these concerns. In addition a survey of Audiologists and Audiometrists current practices and knowledge about the interaction between ‘minimal’ hearing loss and classroom acoustics would be informative and provide a guideline as to what information these professionals need to become more aware of this area of Educational Audiology.
Research Question 4. What are the levels of background noise Australian school children are exposed to during various classroom activities. From the sound level measurements recorded it is obvious that the children are being exposed to substantial amounts of noise in their classroom. The ambient noise without air-conditioning was between 10 and 19 dBA louder than recommended by the American-Speech-Language-Association (ASHA), but with the air-conditioning unit working, this increased to between 20 and 24 dBA louder than recommended. As previously stated Crandell and Smaldino have noted that it is the signal-to-noise ratio that is the most critical factor in classroom communication – with ASHA recommending at least a +15 signal to noise ratio (SNR). The present study found that the SNR varied according to the distance from the teacher and the degree of background noise - with the best ratio for children seated close to the teacher without the air-conditioning operating, providing a +10 to +20 SNR depending on the teachers voice quality. The worst SNR ratio obtained during whole group instruction, was when the air-conditioning was operating - providing a SNR of -5 to +10. This poses a dilemma for the classroom teacher as to whether they should have ‘cool’ (or ‘warm’) air-conditioned air to keep the children’s environment comfortable and to ensure a healthy ‘air-flow’ as a safeguard against the "sick building syndrome" or let the children cope with the heat or cold to reduce the noise in the classroom. Different classroom activities produced different noise levels, with group work generating the noisiest environment with readings of 75 dBA to 80 dBA. In this situation the SNR ratio of the teachers voice within the focus teaching group ranged between -4 to +4 depending on the individual teachers voice quality. These results are similar to previous research , however the additional information regarding the noise in the classroom under the ‘group work’ conditions is particularly informative and not usually available. One study to report on these levels was done by Roeser, Coleman and Adams and they found noise levels above 90 dBA in school classrooms which is a potentially dangerous level for hearing damage to occur. With previous research also recording high levels of noise in classrooms, the noise levels in the present study could be reflective of the noise levels in many Australian classrooms – however future research needs to be conducted to confirm or refute this. Nonetheless, this finding directly impacts on to the concern about boys and group work with Rowe and Rowe making the recommendation that boys need to have more teacher directed work than group work. From the above information about the very high noise levels generated during group work, it could be speculated that it is the high noise levels generated by group work combined with boys ‘slower’ processing of speech that contributes significantly to the research findings that boys learn better under teacher directed work than group work situations. This could be investigated in future research.
Implications The present study has attempted to highlight two areas of immense educational importance: (i)children’s hearing acuity against background noise and the relationship between this and their attentional behaviours; and (ii) the detection of children’s hearing acuity against background noise.
(i)Hearing acuity against background noise and attention Teachers are perceiving behaviours that can be classified as "inattentive". What then causes this inattentive behaviour? Extrapolating from the research on hearing difficulties and classroom acoustics detailed in Chapter 1, there is evidence that many children are unable to hear sufficiently well to keep up their ‘attention’ in classrooms with poor acoustical environments. In addition it has been proposed that by not providing sufficiently loud and clear speech signals to children, they are actually learning to become inattentive to sound . Thus, it could be proposed that attentional problems in school children are caused and exasperated by the interaction between their hearing ability and the poor classroom acoustics. In other words it could be stated that by not providing an intelligible signal to the child today, schools are not only denying the child education on that day, but also the next and in the future, because of this learned inattention. Future research is needed to confirm this. Attention is an important area of educational research because of the huge effect inattentive behaviours have on the educational outcomes of the students behaving that way. Research has indicated that the child’s attention in class is a very important predictor of academic success. Rowe and Rowe state that:When children’s attentiveness is mentioned, Attention Deficit Hyperactivity Disorder (ADHD)(see Appendix A(v)) comes to mind and the question is raised about the relationship between ADHD and hearing ability and classroom acoustics. Although there have been questions raised as to whether there is in fact a theoretical basis for the condition of Attention Deficit Hyperactivity Disorder , I could not find any research investigating the possible links between minimal hearing loss/difficulty hearing-against-background-noise and ADHD. Nonetheless, Barkley (1997) presents an extensive amount of evidence that the predominantly inattentive subtype of ADHD could in fact be unrelated to ADHD - he states that: In addition, Levy and Hay reviewed current research within the area of Genetics and ADHD and their views concur with Barkley that the inattentive subtype could be quite a distinct condition to the Hyperactive and Impulsive ADHD subtypes. They state: As well as these prominent researchers having doubts about the inattentive subtype of ADHD, the validity of all the ADHD categories have been questioned by the US National Institutes of Health, which released a consensus statement on the diversity of opinions about ADHD that "...raises questions concerning the literal existence of the disorder, whether it can be reliably diagnosed" . The research opportunities raised by this situation are exciting, as this means that with a comprehensive research design that includes classroom behaviours and tests for ‘minimal hearing loss’, otoacoustic emissions and ‘real life’ hearing tests as well as the examination of classroom acoustics - there is a chance to discover the real cause of ‘inattention’ and its relationship with hearing ability and classroom acoustics.
(ii) The detection of children’s hearing acuity against background noise Another focus of this research study was to assess the G-F-W’s usefulness as a ‘real-life’ hearing test. The G-F-W has provided significant results in the present research study. These results have shown that children with substantial difficulty discriminating words-against-background-noise are more likely to behave in particular ways in the classroom, and are more likely to have speech-language difficulties. The usefulness of this test in assessing ‘real life’ hearing abilities has therefore been established to this degree. However, as was mentioned earlier, as the G-F-W is paced very slowly this test is not able to discern children with speed of speech processing problems, nor does it attempt to assess children who fatigue during listening activities. The assessment of these areas require different tests. However, taking into account the criticisms of standard audiometry mentioned previously, the G-F-W is a more valid test for determining the ‘real-life’ listening challenges of children in ordinary classrooms than pure-tone tests. This leads on to the question of why there is a virtual absence of hearing-against-noise testing by audiologists. As mentioned earlier it is usually only those children who are selected to have central auditory processing tests that are given this opportunity. One of the possible reasons for this, could be the general lack of educational audiologists in Australia, and the non-existence of specialist educational audiology courses in this country (educational audiology is given a few hours attention as part of the generalist Masters courses in Audiology). Thus, perhaps audiologists and audiometrists (who complete a TAFE course) are unaware of the concerns raised in this paper. In Australia to become and audiologist a two year Masters course is completed. However, in the UK (in addition to the Masters courses) a four year BSc undergraduate course is available at UCL in recognition of the increasing amount of specialised training that is necessary and the increased number of audiologists required to service the ‘hard of hearing’ in the UK. In the US educational audiology is much more common, however there is still a shortfall of educational audiologists to provide services for the children who need them with fewer than 1% of children with hearing problems being served . In addition according to Blair there is a lack of training such that educational audiologists are working less effectively in the school system than they could be. Thus, it seems that if more opportunities became available within educational audiology in Australia, we could be facing quite a ‘shortfall’ of audiologists and perhaps this situation needs to be planned for – like in the UK with the undergraduate courses.
Summary and Conclusions This paper has attempted to bring together the knowledge gained from previous research and the results from the present study of hearing-acuity-against-background noise. From this body of research it is evident that for children to access educational opportunities they need to be able to ‘hear well enough’ to understand what the teacher is saying. It has also been established that classrooms are auditory learning environments and yet most classrooms have very poor acoustics. For more than twenty years well designed research studies have found that a large proportion of children are unable to fully access educational opportunities due to the interaction between their personal qualities and the classroom acoustics. For this same period of time solutions to these problems have been available i.e. FM Amplification. Some school districts in the US (in particular) have implemented FM Amplification and have reaped the (i)financial benefits (through decreased costs of special education); (ii)improved educational outcomes (and happier students); (iii)healthier and happier staff (through improved student attention, improved participation by students, decreased teacher voice problems) . Other schools have been more reluctant to ‘take the plunge’ and have resisted using FM Amplification to help children develop their potential. One of the reasons why there is some reluctance could be: In addition to the modification of classroom acoustics through an FM Amplification system that benefits all of the children all of the time for a small financial capital investment, specific teaching strategies can be implemented to help children gain the most out of their listening. These strategies from Rowe and Rowe have been outlined in Appendix A and include: The teacher : As well as these teaching strategies, specific sound therapies can be undertaken by children who have difficulty hearing against background noise. Various therapies have been successful at improving this ability - for example: Some of these therapies are available in Australia, many at a large financial cost to either the provider (Education departments, or Hospitals) or to the parent(s)/caregiver(s) of the child concerned. In conclusion, I am optimistic that when audiologists, speech-language pathologists, educators and parent(s)/caregiver(s) have more knowledge about the detection of and the high incidence of hearing difficulties and the interaction between the individual’s hearing ability and classroom acoustics, that children with educationally significant hearing difficulties will be identified and provided with adequate speech-to-noise ratios in the classroom - so that they, along with their ‘normal hearing’ peers, can also reach their full life potential.
Future Research Directions The following are some of the possible directions for future research that the current study has raised. (i) ADHD-Inattentive Further investigation into the causes of ADHD-Inattentive subtype. With specific focus on children who have been identified as ADHD-I and the relationship between hearing-against-background-noise, classroom acoustics, speed of auditory processing, fatigue and pure-tone assessments and the child’s behaviours. Co-morbidities would be identified and specific remediation provided along with FM Amplification as a treatment condition so that its efficacy could be assessed.
(ii)ADHD-Hyperactive and Impulsive Children with these conditions could be assessed for real-life hearing difficulties as well. A hypothesis could be tested : that these children have hearing difficulty as an underlying cause and just react to the difficulty in a Hyperactive and Impulsive way as compared to the Inattentive children’s behaviour.
(iii)Real-life hearing assessments More research into the usefulness of various real-life hearing assessments need to be undertaken. With various hearing-against-background-noise tests assessed as well as tests that would also measure fatigue and the speed of speech processing. With the hope that these would complement or replace pure-tone assessments in the near future.
(iv)Therapies for various central auditory processing deficits A variety of therapies need to be assessed in order to provide the best intervention for children affected by background noise, and other central auditory problems.
(v) Large scale implementation of FM Amplification systems into classrooms A large scale study of the implementation of FM Amplification systems into a number of schools. The study would monitor – staff training; organisational change factors; cost-benefit analysis; the hearing abilities, academic and social levels of the children before and during the implementation and use of the FM Systems. Pre and post noise levels of the classrooms under various teaching conditions. Specific remedial therapies could also be evaluated in this study.
(vi)Audiologists and Audiometrists knowledge about the interaction of ‘minimal’ hearing loss and classroom acoustics. A large scale survey of audiologists and audiometrists knowledge of ‘minimal’ hearing loss and classroom acoustics, would be informative and could lead to the development of information packages and training so that generalist audiologists and audiometrists would be able to service these children adequately.
REFERENCES
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