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Effect of contralateral noise on speech detection and speech reception thresholds
Summary
Central masking affects speech detection and reception thresholds, especially at higher noise levels. Pulsed noise significantly impacts speech detection more than continuous noise.
Area of Science:
- Audiology
- Auditory Neuroscience
- Speech Perception
Background:
- Understanding auditory masking is crucial for diagnosing hearing impairments.
- Contralateral acoustic and neural pathways play a role in auditory processing.
Purpose of the Study:
- To investigate the effects of contralateral white and speech noise on speech detection thresholds (SDT) and speech reception thresholds (SRT).
- To examine the influence of continuous versus pulsed noise maskers on these thresholds.
- To explore the underlying mechanisms of masking, including central masking, transcranial conduction, and acoustic reflex.
Main Methods:
- 20 normal-hearing listeners participated.
- SDT and SRT were measured using spondee words.
- Contralateral white or speech noise maskers were presented at various sensation levels (30-80 dB SL).
- Maskers were presented continuously or pulsed.
Main Results:
- Small but consistent threshold shifts were observed at low masker sensation levels (30 dB).
- Threshold shifts increased by approximately 3.5 dB for every 10-dB increase in masker sensation level from 60-80 dB.
- Pulsed maskers resulted in larger shifts for SDT compared to continuous maskers.
- Overall average threshold shifts ranged from 1 to 11 dB across sensation levels.
Conclusions:
- Central masking is likely operating at masker sensation levels below 60 dB.
- At higher sensation levels (above 60 dB), threshold shifts are attributed to a combination of central masking, transcranial conduction, and acoustic reflex.
- These findings have clinical implications for understanding and evaluating auditory processing in noise.