  In this paper, we consider the effect of a bandwidth extension of narrow-band
speech signals (0.3-3.4 kHz) to 0.3-8 kHz on speaker verification. Using
covariance matrix based verification systems together with detection error
trade-off curves, we compare the performance between systems operating on
narrow-band, wide-band (0-8 kHz), and bandwidth-extended speech. The
experiments were conducted using different short-time spectral
parameterizations derived from microphone and ISDN speech databases. The
studied bandwidth-extension algorithm did not introduce artifacts that affected
the speaker verification task, and we achieved improvements between 1 and 10
percent (depending on the model order) over the verification system designed
for narrow-band speech when mel-frequency cepstral coefficients for the
short-time spectral parameterization were used.
