Distinct brain regions process sound intensity versus perceived loudness differently

Evidence

The stimuli employed were 4 kHz-bandpass filtered noise stimuli, presented monaurally to each ear at levels from 37 to 97 dB SPL. One diotic condition and a silence condition were included as control conditions. Normal hearing listeners completed a categorical loudness scaling procedure with similar stimuli before auditory fMRI was performed. The relationship between brain activity, as inferred from blood oxygenation level dependent (BOLD) contrasts, and both sound intensity and loudness estimates were analyzed by means of linear mixed effects models for various anatomically defined regions of interest in the ascending auditory pathway and in the cortex. The results indicate distinct functional differences between midbrain and cortical areas as well as between specific regions within auditory cortex, suggesting a systematic hierarchy in terms of lateralization and the representation of sensory stimulation and perception. — Dijk, Pim van, Physiology, Psychoacoustics and…, 2607

Categorization

• corroborated: 2 independent passages support this claim — Dijk, Pim van, Physiology, Psychoacoustics and…, 2607
• XREF: connects to: Auditory cortex activation linearly reflects perceived loudness rather than physical intensity — Dijk, Pim van, Physiology, Psychoacoustics and…, 2610; Recruitment patients could disambiguate loudness from intensity encoding in fMRI; Subcortical auditory structures encode sound intensity linearly while cortex compresses it. — Dijk, Pim van, Physiology, Psychoacoustics and…, 2645 (+2 more)

Broader Connections

• Auditory cortex activation linearly reflects perceived loudness rather than physical intensity #corroborates (0.95) — Dijk, Pim van, Physiology, Psychoacoustics and…, 2610
• Subcortical auditory structures encode sound intensity linearly while cortex compresses it. #expands (0.85) — Dijk, Pim van, Physiology, Psychoacoustics and…, 2645
• Recruitment patients could disambiguate loudness from intensity encoding in fMRI #corroborates (0.80)
• Loudness perception involves central mechanisms beyond cochlear vibration #corroborates (0.80)
• Perceived loudness and physical sound intensity follow different, non-intuitive mathematical scales #corroborates (0.80) — George Michelsen Foy, Zero Decibels, 53