  Hearing loss (HL) simulators, which allow normal hearing (NH) listeners to
experience HL, have been used in speech intelligibility experiments, but not in
sound quality experiments due to perceptible distortion. If they produced less
distortion, they might be useful for NH listeners to evaluate the sound quality
of, for example, hearing aids. We conducted perceptual sound quality
experiments to compare the Cambridge version of HL simulator (CamHLS) and the
Wakayama version of the HL simulator (WHIS), which has the two algorithms of
filterbank analysis synthesis (FBAS) and direct time-varying filter (DTVF). The
experimental results showed that WHIS with DTVF produces less perceptible
distortion in speech sounds than CamHLS and WHIS with FBAS, even when the
nonlinear process is working. This advantage is mainly due to the use of the
DTVF algorithm, which could be applied to various signal synthesis applications
with filterbank analysis.
