Children's speech recognition in noise using omni-directional and dual-microphone hearing aid technology.

OBJECTIVE The purpose of this study was to examine children's speech recognition abilities for words and sentences presented in background noise when the children used omni-directional and dual-microphone hearing aid technology. DESIGN Twenty children (ten 4- to 6-yr olds; ten 7- to 11-yr-olds) with bilateral cochlear hearing loss (average four-frequency hearing loss = 57.25 dB HL; range: mild to severe) were included in the study. An adaptive test procedure was used to estimate a signal to noise ratio (SNR) that reduced individual speech recognition ability to 50% in multi-talker background competition. Testing was completed with the child seated in a conventional audiologic test suite. A fixed level of the speech signal was delivered through a loudspeaker located at 0 degrees; noise varying in 2 dB steps was presented at 180 degrees. SNR was estimated for two types of speech materials (closed-set words and sentences). Children wore binaural programmable hearing aids (Phonak PiCS) and were tested in conventional omni-directional and dual-microphone ("Audio Zoom") conditions. RESULTS Significant effects of microphone condition, speech material type (words and sentences), and age group ("younger" and "older") were revealed by mixed design analysis of variance. Overall, children received a mean advantage of 4.7 dB from listening in the dual-microphone condition. Children's performance was correlated with their chronological age and language age (receptive vocabulary) but not with their degree of hearing loss (except in one condition). Younger children required a more advantageous SNR to achieve the same performance criteria as older children. CONCLUSIONS Under the specific test conditions used in this investigation, dual-microphone hearing aid technology provided a significant listening advantage in background competition over conventional omni-directional microphones for children with mild to severe cochlear hearing loss for both word and sentence test materials.