Elevated hearing thresholds and lower LDLs compress loudness category spacing horizontally.

Evidence

Compared to NH04, listener NH01 has a wider range of levels that correspond to 5 CU (“Very Soft”) and a lower LDL, leaving a smaller dynamic range for the remaining categories. This results in a horizontally-compressed MCPF, mirroring the listener’s sharper growth of loudness in the CLS function. … Listener HL11 (4th row) has LDL that is within the ranges of a NH listener; the higher threshold level causes the spacing between category boundary curves to be compressed horizontally. Despite this compression, this listener with HL has well-defined perceptual boundaries between categories (i.e., sharply-sloped boundary curves). — Dijk, Pim van, Physiology, Psychoacoustics and…, 2556

Categorization

• corroborated: 2 independent passages support this claim — Dijk, Pim van, Physiology, Psychoacoustics and…, 2556
• XREF: connects to: Elevated hearing thresholds impair spatial separation of direct sound from room reflections.; Sensorineural hearing loss compresses the full loudness range into fewer decibels — Jennifer Lentz, Psychoacoustics- Perception of Normal…, 838; Hearing loss squeezes the full loudness range into a much smaller dynamic range (+2 more)

Broader Connections

• Hearing loss squeezes the full loudness range into a much smaller dynamic range #corroborates (0.90)
• Sensorineural hearing loss compresses the full loudness range into fewer decibels #expands (0.85) — Jennifer Lentz, Psychoacoustics- Perception of Normal…, 838
• Loudness recruitment shrinks dynamic range while preserving overall loudness #expands (0.82)