Evaluation of phoneme compression schemes designed to compensate for temporal and spectral masking in background noise.

The effect of phonemic compression has been studied on speech intelligibility in background noise in hearing-impaired listeners with moderate-to-severe high-frequency losses. One configuration, anti-upward-spread-of-masking (anti-USOM) focuses on a release from spectral masking of high-frequency speech cues by selective spectral tilting. Release from temporal masking is the main goal of a second configuration, high-pass filtered compression (HFC), which reduces the speech modulations within a high-pass filtered compression channel. Speech intelligibility was measured with consonant-vowel-consonant (CVC) words in a multi-talker babble and a single-talker background noise. Anti-USOM has a significant negative effect on the phoneme scores in background noise. HFC compression tends to improve vowel intelligibility in a single-talker background noise, especially for the listeners with a relatively poor speech score. In a multi-talker babble noise the effects of HFC compression tend to be negative. It can be concluded that no significant release from spectral or temporal masking is obtained by the applied processing.