Quantifying the contribution of vision to speech perception in noise

Area of Science:

• Audiology
• Speech Perception
• Psycholinguistics

Background:

• Visual cues enhance speech intelligibility in noisy environments.
• Quantifying the audiovisual benefit and its relation to individual differences is crucial for understanding speech perception.

Purpose of the Study:

• To quantify the audiovisual benefit in speech reception.
• To correlate this benefit with individual lipreading ability and sentence lipreading difficulty.

Main Methods:

• Measured auditory and audiovisual speech-reception thresholds (SRTs) in 20 normal-hearing listeners.
• Used 60 sentences varying in lipreading difficulty, presented in white noise.
• Defined SRT as the lowest signal-to-noise ratio for correct identification of key words.

Main Results:

• Audiovisual benefit averaged 11 dB, with significant variation among subjects and sentences.
• Audiovisual benefit strongly correlated with visual-alone lipreading performance (r=0.86).
• Easier-to-lipread sentences showed greater audiovisual benefit (r=0.92).

Conclusions:

• Audiovisual benefit is a reliable measure of lipreading ability.
• This study provides a basis for an efficient speech-reception disability test.
• The proposed method avoids floor and ceiling effects common in percentage-correct measures.