| Multichannel amplitude compression processing is used to reduce the level variations of speech to fit the reduced dynamic ranges of listeners with sensorineural hearing loss. This processing, however, can result in smearing of temporal information, artifacts due to spectral discontinuities at fixed channel edges, and spectral flattening due to reduced peak-to-valley ratios. An implementation of a time-varying compression processing algorithm based on a sinusoidal speech model (Col-SM) operates on a time-varying, stimulus-dependent basis to adjust to the speech variations and the listener's hearing profile. The algorithm provides fast-acting compression with minimal audible artifact, has time-varying frequency channels, is computationally inexpensive and preserves the important spectral peaks in speech. Presented here is a Col-SM based algorithm that determines the levels of key spectral peaks and valleys to achieve time-varying compression amplification with spectral sharpening. The amount of sharpening can be set individually based on the needs of the listener. The algorithm has been adapted to operate in noisy environment. Preliminary subject tests will be presented. |
