Hearing loss impairs spatial sound separation, not just frequency detection.
Evidence
- Noise-induced hearing loss is characterized by elevated thresholds around 4 kHz. Presbycusis, the hearing deterioration that occurs with age, starts at the highest frequencies and progresses downward. These data showed that by itself, high-frequency hearing loss did not correlate well with trends in judgment variability (see Figure 10.5(b)). Instead, it was hearing level at lower frequencies that showed the correlation (Figure 10.5(a)). Some listeners with high-frequency loss had normal hearing at lower frequencies, but all listeners with low-frequency hearing loss also had loss at high frequencies—in other words, it was a broadband problem. We now know that elevated hearing thresholds are often accompanied by reduced ability to separate sounds in space, which would include separating the listening room from the sound of the loudspeaker, which adds significant difficulty to the task. This is very likely a broadband effect; see Chapter 16. This suggests that eliminating room reflections might be advantageous for those with hearing loss. — Toole, Floyd E, Sound reproduction- the acoustics and…, 1066
The tests involved evaluations of Spatial Release from Masking (SRM), which is a measure of the angular separation between a “target” voice and an interfering voice necessary for the listener to be able to spatially separate them. This relates to the ability to separate images in a soundstage, something of increased importance in immersive audio. Srinivasan et al. (2016) concluded that young-normal-hearing listeners could discriminate approximately 2°, older-normal-hearing listeners could discriminate approximately 6°, but older-hearing-impaired listeners found little advantage even at 30° separation. In the end, age is a factor, but hearing loss, regular and/or hidden, determines the ability to discriminate among multiple images in a panorama. — Toole, Floyd E, Sound reproduction- the acoustics and…, 1903
Categorization
- XREF: Connects to head-related transfer function and auditory spatial localization literature; also to the reader’s existing knowledge of room acoustics.
- QUESTION: What mechanism links elevated thresholds to degraded spatial release from masking? Worth chasing down the binaural processing evidence.
- DEFINE: Defines Spatial Release from Masking (SRM) and connects it to soundstage image separation in immersive audio.
- corroborated: 2 independent passages support this claim — Toole, Floyd E, Sound reproduction- the acoustics and…, 1066; Toole, Floyd E, Sound reproduction- the acoustics and…, 1903