Rapid Speech Transmission Index

Abbreviated as RASTI and expressed in a decimal range of 0.2 for "bad" to 1.00 for "Excellent"

The method for calculation can be found in IEC 268-16.

This method only uses two octave bands 500Hz and 2000Hz and is only considered to give good results if the background noise has no tonal components and there are no non-linearities in speech transmission.

RASTI - example values
Churches (ref. Carvalho) 0.40

Reference

Antonio P.O. Carvalho, "Relations between rapid speech transmission index (RASTI) and other acoustical and architectural measures in churches" Applied Acoustics, 58 (1999) 3349

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Subjects: Audio