The effect of presentation level on spectral weights for sentences

Area of Science:

• Auditory perception
• Speech processing
• Psychoacoustics

Background:

• Psychophysical studies show spectral weights increase with presentation level at high frequencies.
• The role of presentation level in spectral weighting for speech perception is not fully understood.

Purpose of the Study:

• To investigate if spectral weights for speech perception are affected by presentation level.
• To compare spectral weighting in normal-hearing listeners at different sound pressure levels (SPL) with data from hearing-impaired listeners.

Main Methods:

• Sentences were filtered into five frequency bands.
• Stimuli were presented at two presentation levels: 75 dB SPL and 95 dB SPL.
• Spectral weights were estimated for normal-hearing listeners.

Main Results:

• For the highest frequency band (2807-10,000 Hz), spectral weights were higher at the 95 dB SPL level compared to the 75 dB SPL level.
• Spectral weights at 95 dB SPL in normal-hearing listeners were similar to those previously reported for hearing-impaired listeners.
• This indicates that high presentation levels may mimic some effects observed in hearing impairment.

Conclusions:

• Presentation level significantly influences spectral weights for speech perception in normal-hearing listeners, particularly at high frequencies.
• Hearing loss may play a less significant role in spectral weighting for sentence recognition than previously thought, as high presentation levels can yield similar weighting patterns.
• These findings have implications for understanding speech perception in noisy environments and in individuals with hearing loss.