Referring to the previous post concerning AI (Articulation Index) approach to voice quality measurement we would like to present another one: SII (Speech Intelligibility Index) which is the evolution of AI method. The American Standard ANSI S3.5-1997 includes the speech intelligibility index. It provides 4 measuring procedures on different band groups: 21 critical bands, 18 one third-octave bands, 17 equal by their contribution critical bands and 6 octave bands. The signal/noise ratio is calculated within every band and the total SII coefficient ranged from 0 to 1 is computed.
The speech intelligibility index takes into account only the properties of hearing, not speech production and that is an obvious disadvantage of the method..
More methods to automate voice quality analysis are about to follow in the next posts!
