Factors affecting the development of speech recognition in steady and modulated noise.

This study used a checkerboard-masking paradigm to investigate the development of the speech reception threshold (SRT) for monosyllabic words in synchronously and asynchronously modulated noise. In asynchronous modulation, masker frequencies below 1300 Hz were gated off when frequencies above 1300 Hz were gated on, and vice versa. The goals of the study were to examine development of the ability to use asynchronous spectro-temporal cues for speech recognition and to assess factors related to speech frequency region and audible speech bandwidth. A speech-shaped noise masker was steady or was modulated synchronously or asynchronously across frequency. Target words were presented to 5-7 year old children or to adults. Overall, children showed higher SRTs and smaller masking release than adults. Consideration of the present results along with previous findings supports the idea that children can have particularly poor masked SRTs when the speech and masker spectra differ substantially, and that this may arise due to children requiring a wider speech bandwidth than adults for speech recognition. The results were also consistent with the idea that children are relatively poor in integrating speech cues when the frequency regions with the best signal-to-noise ratios vary across frequency as a function of time.