Excess Vowel Fusion in Hearing-Impaired Listeners Across Fundamental Frequency and Spatial Separation in the Free Field: An Alternative Mechanism for Difficulties With Speech in Noise

Binaural fusion occurs when signals arriving separately at the two ears are perceived as one sound. Previously, it was shown that normal-hearing (NH) or hearing-impaired (HI) listeners fused and perceptually averaged dichotic vowels presented through headphones....

This study proposes excess vowel fusion as an additional mechanism for speech-in-noise difficulty in hearing-impaired listeners, but findings are preliminary and do not yet support changes to clinical assessment or fitting protocols.

Identifying excess vowel fusion as a distinct mechanism for speech-in-noise difficulties could eventually inform new rehabilitation targets and hearing-aid processing strategies beyond current signal-to-noise ratio frameworks.

1. 01Hearing-impaired listeners showed greater vowel fusion than normal-hearing listeners across pitch (F0) and spatial separation conditions.
2. 02Excess fusion persisted even when fundamental frequency and spatial cues were varied, suggesting a robust perceptual deficit.
3. 03The findings propose an alternative — or complementary — mechanism to auditory masking for speech-in-noise difficulties.
4. 04Study was conducted in the free field, adding ecological validity compared with headphone-only paradigms.
5. 05Results could eventually motivate novel hearing-aid processing strategies targeting stream segregation.

PMID

42500955

DOI

10.1177/23312165261473398.

Journal

Trends in Hearing

Publication type

research_article

Evidence level

2b

Population

Hearing-impaired listeners compared with normal-hearing listeners in a free-field listening experiment

Intervention

Vowel fusion task with manipulated fundamental frequency (F0) and spatial separation of sound sources

Comparator

Normal-hearing listeners