Intelligibility of selected passages from the Speech Intelligibility Rating (SIR) test

Area of Science:

• Audiology
• Speech Science
• Psychoacoustics

Background:

• The Speech Intelligibility Rating (SIR) test uses passages from Cox and McDaniel (1984, 1989).
• Assessing speech intelligibility requires controlled listening conditions.

Purpose of the Study:

• To evaluate the intelligibility of 12 passages from the SIR test.
• To compare the effectiveness of two different masking noise types.

Main Methods:

• Two experiments were conducted using a method-of-adjustment procedure.
• Speech intelligibility was measured in the presence of multi-talker babble and signal-correlated noise.
• Signal-to-noise (S/N) ratios were varied in the babble condition and held constant in the signal-correlated noise condition.

Main Results:

• Two homogeneous subsets of nine passages each were identified that yielded equivalent intelligibility scores.
• Signal-correlated noise provided level-independent intelligibility scores.
• Multi-talker babble resulted in potentially level-dependent scores due to variations in passage speech intensity.

Conclusions:

• Signal-correlated noise is a valuable masker for speech intelligibility testing.
• This masker yields scores less affected by variations in signal level between passages.
• The findings support the use of signal-correlated noise for more robust SIR test development.