الفهرس 
Review of LiteratureOnly 14 pages are availabe for public view
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Abstract
1. CAEPs-P1 to short duration stimuli was successfully recorded in all hearing impaired children in aided and unaided conditions with shorter latencies and higher amplitudes in aided condition.
2. ACC to short duration stimuli either tonal or speech was successfully recorded in hearing impaired children in aided and unaided conditions with higher detectability in aided condition.
3. Detectability % of CAEP-P1 was higher than ACC, reflecting better cortical detection than discrimination ability in hearing aid users. However, both evoked potentials showed better responses with hearing aids.
4. Tonal stimulus is preferable than speech in noise stimuli to elicit ACC response in hearing aid users with a 50 gap-in-tone stimulus as a start point.
5. Increase signal to noise ratio yields better discrimination in background noise in hearing aid users.
6. Hearing aid users could perform central auditory tests that reflect different abilities but with high scores as shown in speech in noise test &thresholds as revealed in AF test.
7. Questionnaire is an easy, simple & quick test that can give an idea about child behavioral in different auditory situations.
8. ACC gap detection thresholds could give a clue about performance of hearing impaired children in behavioral measures (e.g Word in noise test) better than ACC latency/amplitude.
Recommendations
1- ACC can be used as a useful objective tool to assess auditory discrimination and perception in noise abilities in hearing aid’ users in complementary with behavioral tests.
2- Incoming researches are recommended to emphasize on technical features of HAs that are beneficial for speech understanding in noise e.g directional microphone.
3- Further researches are recommended to use the same type of noise maskers in behavioral and objective tests.
4- Language evaluation is recommended to be involved in the coming researches to complete the test battery evaluation in hearing aid’ users.
5- Further researches are recommended to explore ACC finding in ANSD populations.
Summary
Children with mild-to-severe hearing loss are at risk for delayed language development. The risk increases with increasing severity of hearing loss. However, Early amplification provides better early language outcomes, as well as Consistent hearing aid use provides some protection against language delay and supports auditory development. Monitoring the hearing-related outcomes of infants and children with hearing loss and fitted with suitable hearing aids is essential and can be accomplished both objectively and subjectively.
Many subjective tests are employed to identify and monitor performance of H.A users. Questionnaire is one of the behavioral tests that could be completed by parents or caregivers. Evidence-based protocols enhance the audiologists’ ability to use aided speech in noise tests to estimate real-world listening skills to monitor and evaluate the hearing aids. Spectral resolution is an important acoustic component in speech perception. Hence, it’s recommended to be evaluated, together, with speech perception in noise ability in children with H.As.
Although audiologists find difficulty to apply the previous tests on young children &/or those with low intelligent quotient (IQ), it could be overcome by using objective tests, one of them is the acoustic change complex (ACC), ACC is a CAEP evoked in response to a change in an ongoing sound. ACC could be elicited using different types of stimuli in normal hearing children, children with hearing aids (HAs) and cochlear implants (CIs).
The aims of the study were to provide an objective tool for assessment of speech perception in noise and temporal resolution abilities in hearing aid users and to correlate ACC to behavioral tests. If ACC is consistent and correlated, this might be considered a step in guiding the H.As performance in children independent of their abilities or degree of cooperation of children.
Sixty Arabic speaking children (34 boys and 26 girls) using binaural H.A device participated in the present study. Their age ranged from 6 to 12 years with a mean 9.6 year. The children were subjected to detailed history taking about duration of speech therapy, duration of H.A use, and evaluation of Hearing aid device performance. It was done in the form of questionnaire, aided sound field thresholds, central auditory tests and aided/unaided cortical (CAEP-P1) and ACC recordings. The replicated ACC waveforms were collected and analyzed and the aided ACC responses were compared with unaided ACC in addition to correlation with behavioral thresholds/scores.
The results of the study pointed that ACC could be successfully recorded in H.As users using relatively short stimuli (500 ms long) with shorter latencies and higher amplitudes with using hearing aids. Objective gap detection threshold could be obtained easily (using tonal stimulus) with better threshold with hearing aids. With background noise stimulus (using vowel/o/ embedded in background noise), the ACC detectability %was affected by noise (SNR0) more than the more favorable SNR (+8), which reflecting the needs of hearing aid users for higher SNRs.
Detectability % of CAEP-P1 was higher than ACC, reflecting better cortical detection than discrimination ability in hearing aid users. However, both evoked potentials showed better responses with hearing aids. In relation to tests for temporal resolution, ACC to gap-in-tone thresholds were significantly negatively correlated to behavioral test for selective auditory attention (Word In Noise test) and questionnaire scores .However; there were no correlations with ACC response parameters (latency and amplitude) using different stimuli.
In conclusion, ACC response parameters could be used to monitor the neuroplasticity of the central auditory nervous system in regular users of H.As, the latency and amplitude could give a clue about the child’s rehabilitation whereas ACC thresholds could give a clue about performance of children with (H.As) in psychophysical measures. ACC to gap-in-tone & to speech embedded in noise can serve as a useful objective tool to assess temporal resolution and speech perception in noise abilities. However, ACC is not suitable to replace psychophysical tests.