Hearing aid benefit in children with mild hearing loss in adverse listening situations

Project goals and methodology

Mild hearing loss is the most common degree of hearing loss, affecting 3-4 out of every 1,000 Australian children aged 0-9. Even mild hearing loss leads to significant challenges in understanding speech in noisy environments commonly found in learning environments like classrooms. However, the benefit of using one or two hearing aids for speech understanding in noise, especially when the locations of speech and noise vary, remains unknown. Further, the degree to which neural processing of sound features influence speech understanding in noisy environments over and above the effects of cognitive and language abilities, is unknown. Uncertainty in device benefit leads to delays in device recommendations, often once children are experiencing developmental delays. A better understanding of performance and factors involved could help audiologists with counselling regarding device fitting and benefit.

Key findings

The study found that children with mild hearing loss performed similarly to normal hearing peers with or without hearing aids in both ears, when needing to use location cues to hear better in noise. However, use of hearing aid in just the worse ear leads to much poorer performance. Hence, when hearing loss occurs in both ears, aiding both ears is recommended; aiding the poorer ear is not optimal.

Using fNIRS, a relatively novel neuroimaging technique that uses changes in blood flow, brain responses to frequency change cues in speech were found to be similar between children with normal hearing and those with hearing loss, only when hearing aids were worn. This highlights the importance of hearing aids in improving the brain’s ability to process sounds with improved audibility.

Better sensitivity to these frequency change cues in the brain regions responsible for processing sound was associated with better speech understanding benefit gained from separating the location of speech and noise. This indicates that differences in benefit gained may share some common processes underlying brain’s sensitivity to frequency changes in sound.

Conclusion

In conclusion, use of bilateral hearing aids neither helped nor deteriorated the ability of children use spatial cues to better understand speech in noise, however, it improved the representation of frequency change cues. Neural responses to these frequency features in speech, previously shown to explain performance only in adults, were found to benefit children’s speech understanding abilities as well.