Fletcher and Munson pioneered equal-loudness contours in 1933 via loudness balancing.

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 (#qualifies, via linked claim)

Categorization

• XREF: connects to: Equal-loudness contours are a fixed property of human hearing — Toole, Floyd E, Sound reproduction- the acoustics and…, 909; Equal-loudness contour data have been repeatedly revised and corrected

Related

• Equal-loudness contours were first measured using 1 kHz reference tones and phons (similarity 0.90)
• Equal-loudness contour data have been repeatedly revised and corrected (similarity 0.89)
• Fletcher and Munson’s 1933 loudness data remain essentially accurate today. (similarity 0.87)
• Equal-loudness contours are a fixed property of human hearing (similarity 0.87)
• Different equal-loudness contour studies disagree substantially in shape (similarity 0.83)
• Equal-loudness contour measurement evolved from anechoic pure tones to reflective-space noise bands (similarity 0.82)
• Fletcher and Munson’s equal-loudness data are no longer trusted (similarity 0.82)
• No single equalization target curve can suit all listeners (similarity 0.81)
• Equal-loudness contours flatten at low frequencies as level rises (similarity 0.79)
• Equalizing to a universal target curve cannot reliably improve sound (similarity 0.79)
• Equal-loudness contours vary greatly across individual listeners (similarity 0.78)

Broader Connections

• Equal-loudness contours are a fixed property of human hearing #qualifies (0.85) — Toole, Floyd E, Sound reproduction- the acoustics and…, 909
• Equal-loudness contour data have been repeatedly revised and corrected #expands (0.80)