“…[2,5] The voice changes may include changes in the pitch, cycleto-cycle variations; jitter, decrease in amplitude; shimmer, loss of power, addition of noises; harmonic to noise ratios, constriction of voice range; i.e., displacement towards lower frequency. [2,3,6,7] The normal acoustic features lie in the frequency range 20 Hz -4,000 Hz, but the pathological voice features are spread over 20 Hz -20 kHz. The changes in the acoustic features may not be noticeable by normal hearing.…”