  We propose an objective intelligibility measure (OIM), called the Gammachirp
Envelope Similarity Index (GESI), which can predict the speech intelligibility
(SI) of simulated hearing loss (HL) sounds for normal hearing (NH) listeners.
GESI is an intrusive method that computes the SI metric using the gammachirp
filterbank (GCFB), the modulation filterbank, and the extended cosine
similarity measure. The unique features of GESI are that i) it reflects the
hearing impaired (HI) listener's HL that appears in the audiogram and is caused
by active and passive cochlear dysfunction, ii) it provides a single goodness
metric, as in the widely used STOI and ESTOI, that can be used immediately to
evaluate SE algorithms, and iii) it provides a simple control parameter to
accept the level asymmetry of the reference and test sounds and to deal with
individual listening conditions and environments. We evaluated GESI and the
conventional OIMs, STOI, ESTOI, MBSTOI, and HASPI versions 1 and 2 by using
four SI experiments on words of male and female speech sounds in both
laboratory and remote environments. GESI was shown to outperform the other OIMs
in the evaluations. GESI could be used to improve SE algorithms in assistive
listening devices for individual HI listeners.
