The speech transmission index measures intelligibility via a modulation transfer function
Evidence
Another objective measure is the speech transmission index (STI) (IEC, 2003; Houtgast and Steeneken, 1985), which uses a modulation transfer function approach to measure the effect of a given situation on speech intelligibility. It works for most forms of speech degradation and shows good correlation with subjective tests (Steeneken and Houtgast, 1994). It also has the advantage of being relatively easy to calculate, and so can be used in simulations to predict likely improvements in performance. — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 2558
Categorization
- DEFINE: Defines STI as a modulation-transfer-function based objective metric that predicts speech intelligibility across most degradation types.
- XREF: STI generalizes the older Articulation Index / AI and RASTI measures; connects to the field’s broader thread of objective speech-intelligibility prediction.
Related
- Speech intelligibility estimates compress 98 MTF values into one index (similarity 0.83)
- Speech intelligibility indexes average signal-to-noise ratio across critical bands (similarity 0.83)
- Speech intelligibility measures the proportion of correctly identified transmitted messages (similarity 0.82)
- Speech intelligibility metrics can be predicted from impulse response and noise (similarity 0.80)
- Speech intelligibility can be predicted by measuring signal envelope modulation decay (similarity 0.80)
- The SII model mispredicts intelligibility of sharply filtered speech and noise (similarity 0.79)
- Reverberation time and signal-to-noise ratio map onto the same speech intelligibility scale (similarity 0.78)