Equal-loudness contours are a fixed property of human hearing

Evidence

The equal-loudness contours describe a characteristic of our hearing systems that is always there and unchanged whether we are at a live musical performance, having a conversation, or listening to music or movies at home. They are part of the human listener, not something that needs to be “corrected” for, as some have mistakenly believed. They are typically measured using pure tones at different frequencies that are compared to a reference tone at 1 kHz and adjusted to be equally loud. It is a simple process using simple sounds, and the real question is the extent to which these curves relate to the complex continuous spectra of music. It is an issue to which there is no definitive answer. — Toole, Floyd E, Sound reproduction- the acoustics and…, 909

Categorization

• DEFINE: Defines what equal-loudness contours are and how they are measured, clarifying a core psychoacoustic concept.
• QUESTION: The unresolved link between single-tone equal-loudness curves and complex music spectra is worth chasing into the literature.
• corroborated: 2 independent passages support this claim — Toole, Floyd E, Sound reproduction- the acoustics and…, 909
• XREF: connects to: The phon unit anchors loudness to perceived equality across frequencies rather than raw SPL — Eric J. Heller, Why You Hear What You Hear- An…, 2002; Equal-loudness contour data have been repeatedly revised and corrected; Equal-loudness contours vary greatly across individual listeners (+5 more)

Broader Connections

• Loudness depends on frequency, angle, duration, and envelope, not just level #complicates (0.85) — Toole, Floyd E, Sound reproduction- the acoustics and…, 903
• Equal-loudness-contour weighting schemes failed as loudness meters #complicates (0.80)
• Loudness is measured subjectively against 1 kHz reference tones #exemplifies (0.80) — Professor Dr.-Ing. Hugo Fastl, Professor Dr.-Ing. Eberhard, Psychoacoustics- Facts and Models, 1169
• Loudness judgments at a fixed level vary probabilistically across categories #complicates (0.75) — Dijk, Pim van, Physiology, Psychoacoustics and…, 2512