Auditory Processing Disorder (APD) is a disorder where the functions of the ear are normal, but the person has difficulty identifying or discriminating sounds and experiences listening difficulties in noise. Remote Microphone Hearing Aids (RMHAs) are wireless listening devices that pick up the speaker's voice and transmit it to a receiver in the listener's ear. In this way, the negative effects of ambient noise, distance from speaker and reverberation are reduced.

The research questions are whether RMHAs improve classroom listening, listening in noise performance, listening in spatialised noise and auditory attention, in children with APD. We hypothesize that RMHA use will lead to improved classroom listening and improved speech-in-noise skills after 6 months of RMHA use. Additionally, we hypothesise that listening in spatialised noise and attention skills will remain unchanged following the intervention period.

Twenty-six (26) children aged 7-12 with a diagnosis of an APD from the Great Ormond Street Hospital Audiology clinic were included in the study.

Auditory Processing Disorder (APD) is a disorder where the functions of the ear (outer, middle, inner) are normal but the person has difficulty identifying or discriminating sounds (1). For children with APD it is particularly difficult to hear when the listening conditions are not ideal. For example, when there is background noise it becomes really challenging to focus on the speaker. Two other factors that influence their hearing ability are reverberation and the distance from the speaker (2). Some symptoms reported for APD are listening difficulties in background noise, attention and memory problems, and distractibility (3,4). Children with APD have worse skills in speech perception in noise compared to typically developing children (5,6) and have also have poorer sustained auditory attention compared to children suspected of APD (7).

Remote Microphone Hearing Aids (RMHAs) are a management approach recommended for children with APD. These are wireless listening devices that pick up the speaker's voice and transmit it to a receiver in the listener's ear. The use of this system helps improve the signal-to-noise ratio for children and bypasses the negative effects of background noise and reverberation in the classroom (2,8,9). There have not been many studies, though. That looked into the effects of RMHA on children with APD. Previous research suggests that children with APD after a prolonged use of RMHAs benefit from improved speech perception which is possibly linked to an enhanced auditory system (9). Adding to that, children with APD have shown improved speech in noise perception when using the RMHA, hence emphasizing the advantages of the device in discriminating speech in background noise (9,10).

Sustained attention and the ability of children with APD to listen in spatialised noise after RMHA use has been examined by one study (10). It did not show improvement (unaided) in any of the two tests. However, this was a non-randomised trial that did not use a control group. As the central point of this study will be the use of the RMHA by children with APD for 6 months, it is expected that the findings could add valuable information on the subject.

Aim and hypotheses The aim of the study is to examine the effect of a 6-month RMHA use on self-reported listening in the classroom, speech perception in noise, speech perception in spatialised noise and on attention skills.

Hypotheses:

i. Children with APD who use RMHAs will show greater improvements in classroom listening, listening in noise and sustained auditory attention (unaided) after 6 months of RMHA use in comparison to the APD control group.

ii. Children with APD who use the RMHA will not show greater improvements in listening in spatialised speech noise and divided and visual attention measures after 6 months of RMHA use in comparison to the APD control group.

Research Design and Methodology Participants and Recruitment We recruited 26 children aged 7-12 years. All children have been diagnosed and referred from the Auditory Processing Disorders Clinic at Great Ormond Street Hospital. The total sample size was decided using this power sample: N = 24 (total sample size) calculated using the F test for repeated measures between-within interaction ANOVA based on an estimated 0.5 effect size f(U), 80% power, at 5% significance, using 2 groups and 3 measurement points. Accounting for a 10% loss due to follow-up, the final study sample size comprised 26 children.

Inclusion criteria:

1. Diagnosis of APD based on clinical tests administered by qualified audiologists as per the clinic's diagnosis protocol.
2. No neurological or pervasive disorder or developmental delay (e.g. Attention Deficit Hyperactivity Disorder, epilepsy, Autism Spectrum Disorder, Developmental Language Disorder, Down Syndrome).
3. Non-verbal cognitive ability score of 85 or greater.
4. Ages between 7-12 years.
5. Native English speakers.
6. No prior use of RMHAs. Subjects were semi-randomly assigned to each of two intervention arms. The two groups were stratified for age and balanced for gender.

Children were given RMHAs to use at school and were compared to the control that did not use any intervention for the study period. Children were enrolled in the study for 6 months. All groups were tested before the start of the RMHA intervention, after 3 months, and at the end of the study (after 6 months).

Explanation of each test:

1. A hearing test (Pure Tone Audiometry approx. 10mins). To determine their hearing is normal.

2. Non-verbal IQ test (Weschler test of non-verbal intelligence). To be performed by the PhD Student. (approx. 15mins). To assess determine whether their intelligence level is above normal.

3. Listening in spatialised noise test (LiSN-S, approx. 15mins). To be administered through the use of headphones by the PhD student. To determine their listening in spatialised speech noise abilities.

4. The Test of Everyday Attention for Children (TEACh). To be conducted as play type activities by the PhD student after receiving sufficient training by the clinical psychologist. (approx. 45mins possibly cut down to 30mins). To assess their attention.

5. Two questionnaires to be filled by the children's parents.

   1. The Children's Communication Checklist-2 (CCC-2). A 70-item questionnaire which screens for communication problems (including language disorders and autism).
   2. The Children's Auditory Performance Scale (CHAPS). It assesses aspects of children's listening.

6. One questionnaire to be completed by the children (Listening Inventory For Education-Revised [LIFE-R] for assessing their listening difficulty.

Data analysis:

Data were analysed in SPSS statistics software, using mixed ANOVA. Group was the between-subjects factor and time was the within-subjects factor.

Ethical issues

School and teacher involvement:

The teachers of the children who received the RMHA were provided with an information sheet and consent form and were required to wear the microphone (which picks up the teacher's voice and transmits it wirelessly to the ear receivers in the child's ear) for the duration of lecture-based subjects. Remote microphone hearing aids are generally beingg provided (funded by the school budget) to some children after clinical recommendations and this is not an unusual situation within the school environment.

We liaised with the teacher of the school to ensure that the school was aware that the student has been issued with the RMHA. A general guide for the system was made available in addition to information conveyed by the PhD student.

Informed consent:

The child's parents were given detailed written information and consent forms to sign. They were given up to a week to study and decide whether they wished for their child to participate in the study. They were only allowed to take part once they have understood the purpose and procedures of the study and they signed the consent forms. In addition, children were also given information sheets adjusted to their age. Written assent from children in the presence of their parents or carers was sought.

Rights to withdraw from the study:

This was outlined on both the information sheet and consent form and explained verbally during test visits. This information stated that participants were allowed to withdraw from the study at any point should they wished to. Withdrawal from the study did not involve any penalty or loss of benefit to them - this information was clearly underlined at the information sheet and verbally communicated.

Data protection:

Parents of the participants and the participants were informed that their information was anonymised and kept confidential. Data was anonymised prior to analysis by the use of participant codes. Storage of the data was in accordance with the data protection act 1998.

Other issues:

None of these tests were invasive or unpleasant, and they were conducted in comfortable sound levels (slightly higher than the usual conversational level).

References

1. Dawes P, Bishop DVM. Auditory Processing Disorder in Relation to Developmental Disorders of Language, Communication and Attention: A Review and Critique. Int J Lang Commun Disord [Internet]. 2009 [cited 2014 Apr 1];44(4):440-65. Available from: http://www.ncbi.nlm.nih.gov/pubmed/19925352
2. Keith WJ, Purdy SC. Assistive and Therapeutic Effects of Amplification for Auditory Processing Disorder. Semin Hear [Internet]. 2014;35(1):27-38. Available from: https://www.thieme-connect.com/products/ejournals/html/10.1055/s-0033-1363522
3. American Speech-Language-Hearing Association. (Central) Auditory Processing Disorders. Technical Report [Internet]. American Speech-Language-Hearing Association. 2005 [cited 2019 Aug 6]. Available from: http://www.asha.org/policy/TR2005-00043/
4. American Academy of Audiology. American Academy of Audiology Clinical Practice Guidelines. Diagnosis, Treatment and Management of Children and Adults with Central Auditory Processing Disorder [Internet]. American Academy of Audiology. 2010 [cited 2019 Aug 6]. p. 1-51. Available from: http://www.audiology.org/publications-resources/document-library/central-auditory-processing-disorder
5. Lagacé J, Jutras B, Giguère C, Gagné J-P. Speech Perception in Noise: Exploring the Effect of Linguistic Context in Children With and Without Auditory Processing Disorder. Int J Audiol [Internet]. 2011;50(6):385-95. Available from: https://www.ncbi.nlm.nih.gov/pubmed/21599614
6. Rocha-Muniz CN, Zachi EC, Teixeira RAA, Ventura DF, Befi-Lopes DM, Schochat E. Association Between Language Development and Auditory Processing Disorders. Braz J Otorhinolaryngol [Internet]. 2014;80(3):231-6. Available from: http://www.ncbi.nlm.nih.gov/pubmed/25153108
7. Allen P, Allan C. Auditory Processing Disorders: Relationship to Cognitive Processes and Underlying Auditory Neural Integrity. Int J Pediatr Otorhinolaryngol [Internet]. 2014;78(2):198-208. Available from: http://dx.doi.org/10.1016/j.ijporl.2013.10.048
8. British Society of Audiology. Practice Guidance. An Overview of Current Management of Auditory Processing Disorder (APD) [Internet]. British Society of Audiology. 2011 [cited 2019 Aug 6]. p. 1-60. Available from: http://www.thebsa.org.uk/docs/docsfromold/BSA\_APD\_Management\_1Aug11\_FINAL\_amended17Oct11.pdf
9. Johnston KN, John AB, Kreisman N V, Hall III JW, Crandell CC. Multiple Benefits of Personal FM System use by Children with Auditory Processing Disorder (APD). Int J Audiol [Internet]. 2009 Jan;48(6):371-83. Available from: http://www.ncbi.nlm.nih.gov/pubmed/19925345
10. Smart JL, Purdy SC, Kelly AS. Impact of Personal Frequency Modulation Systems on Behavioral and Cortical Auditory Evoked Potential Measures of Auditory Processing and Classroom Listening in School-Aged Children with Auditory Processing Disorder. J Am Acad Audiol [Internet]. 2018;19:1-19. Available from: http://www.ingentaconnect.com/content/10.3766/jaaa.16074

Inclusion criteria:

1. Normal audiogram.
2. Diagnosis of APD based on clinical tests administered by qualified audiologists as per the clinic's diagnosis protocol.
3. No neurological or pervasive disorder or developmental delay (e.g. Attention Deficit Hyperactivity Disorder, epilepsy, Autism Spectrum Disorder, Developmental Language Disorder, Down Syndrome).
4. Non-verbal cognitive ability score of 85 or greater.
5. Ages between 7-12 years.
6. Native English speakers.
7. No prior use of RMHAs.

Exclusion criteria:

Any violation of the above conditions.

Adverse event data were collection for a period of 6 months.

The concern that spatial listening of children would be affected by the intervention was monitored through the use of the Listening in Spatialised Noise - Sentences test.

Placebo, Hawthorne or observer bias effects may have influenced the results.