Is pitch a smooth function of frequency? Evidence from octave adjustments

Area of Science:

• Acoustic Musicology
• Psychoacoustics
• Auditory Perception

Background:

• W. D. Ward's 1954 study on melodic octave perception yielded two key findings.
• The octave enlargement phenomenon (average ratio > 2:1) is well-established.
• Ward's finding of a variable octave ratio required further verification.

Purpose of the Study:

• To rigorously test Ward's finding on the variability of the perceived octave frequency ratio.
• To investigate the relationship between pitch and frequency.
• To explore the underlying reasons for octave enlargement.

Main Methods:

• Over 4000 octave adjustments were performed using pure tones at 65 dB SPL.
• Two experiments varied reference frequencies by 50 and 25 cents.
• A third experiment examined listener bias in octave adjustments.

Main Results:

• The frequency ratio defining a perfect octave (Roct) varied significantly with small changes in reference frequency.
• Roct differed notably even for reference frequencies 25 cents apart.
• Octave enlargement was not linked to a preference for a more brilliant or pleasant tone.

Conclusions:

• Pitch perception is not a smooth function of frequency, contrary to common assumptions.
• Listener-specific variations in octave perception are significant.
• Octave enlargement is likely an perceptual artifact rather than a deliberate adjustment for tonal quality.