Effect of individually tailored spectral change enhancement on speech intelligibility and quality for hearing-impaired listeners

Most information in speech is carried by spectral changes over time. We determined if enhancing such changes improves the intelligibility of speech in background sounds for hearing-impaired listeners. The values of four parameters controlling the processing were selected for each subject based on a genetic algorithm. The amount of spectral-change enhancement at a given center frequency increased with increasing hearing loss at that center frequency. A control condition was included with no spectral-change enhancement. The intelligibility of speech was measured for sentences in a speech-shaped noise and in multi-talker babble, using two signal-to-masker ratios, specifically chosen for each subject to avoid floor and ceiling effects. The processing led to small but statistically significant improvements in speech intelligibility for both backgrounds and both signal-to-masker ratios.