  Phase serves as a critical component of speech that influences the quality
and intelligibility. Current speech enhancement algorithms are beginning to
address phase distortions, but the algorithms focus on normal-hearing (NH)
listeners. It is not clear whether phase enhancement is beneficial for
hearing-impaired (HI) listeners. We investigated the influence of phase
distortion on speech quality through a listening study, in which NH and HI
listeners provided speech-quality ratings using the MUSHRA procedure. In one
set of conditions, the speech was mixed with babble noise at 4 different
signal-to-noise ratios (SNRs) from -5 to 10 dB. In another set of conditions,
the SNR was fixed at 10 dB and the noisy speech was presented in a simulated
reverberant room with T60s ranging from 100 to 1000 ms. The speech level was
kept at 65 dB SPL for NH listeners and amplification was applied for HI
listeners to ensure audibility. Ideal ratio masking (IRM) was used to simulate
speech enhancement. Two objective metrics (i.e., PESQ and HASQI) were utilized
to compare subjective and objective ratings. Results indicate that phase
distortion has a negative impact on perceived quality for both groups and PESQ
is more closely correlated with human ratings.
