Equal-loudness contours reflect outer and middle ear amplification characteristics.

Evidence

There are many practical implications for equal-loudness contours. First, the data above suggest that the loudness of sounds across frequency is predominantly determined by the characteristics of the outer and middle ear. Disorders in these structures will alter the relationship between the loudness of sounds across frequency. Second, equal-loudness contours have many practical implications and are used in the design of alarms and sirens and in numerous audio production applications. Further, the A-weighted decibel (dB A) uses the 40-phon loudness contour to calculate a decibel metric that is more similar to the sound level as represented by the human ear. — Jennifer Lentz, Psychoacoustics- Perception of Normal…, 754

Categorization

Category: Causal Relationships

• XREF: The claim that loudness across frequency is dominated by outer/middle ear mechanics rather than the cochlea connects directly to the reader’s hearing-impaired focus — cochlear hearing loss alters loudness growth in ways this baseline clarifies.

Related

• Outer and middle ear damage changes the loudness frequency balance (similarity 0.93)
• Ear sensitivity depends jointly on frequency and on sound level (similarity 0.86)
• Equal-loudness contours are a fixed property of human hearing (similarity 0.84)
• Objective sound amplitude measures do not describe perceived loudness. (similarity 0.84)
• Equal-loudness contours flatten at low frequencies as level rises (similarity 0.84)
• Loudness depends on frequency, angle, duration, and envelope, not just level (similarity 0.84)
• Loudness scales with frequency squared, requiring large amplitude at low frequencies (similarity 0.84)
• Equal-loudness contours vary greatly across individual listeners (similarity 0.84)
• Loudness-growth slope increases with hearing-loss degree but resists exact prediction (similarity 0.83)
• Loudness correlates vary by region, not by a single uniform code (similarity 0.83)
• Loudness at high sound levels arises from excitation spreading across adjacent frequency bands (similarity 0.83)
• Outer and middle ear transfer function determines loudness across frequency. (similarity 0.83)
• Loudness growth with intensity requires experimental quantification, not intuition (similarity 0.83)
• Conductive and cochlear losses produce different loudness growth patterns (similarity 0.83)
• Sensorineural hearing loss produces rapid loudness growth while discomfort thresholds stay normal (similarity 0.83)