Combination tones exist below both source tones and vary in audibility

Evidence

In figure 3.11, the smaller fork is vibrating faster than the larger fork by factor of exactly 3/2. Using f1 = 200 and f2 = 300, the displacement of the smaller tines reads … Notice that it is perfectly periodic. Its frequency is 100 Hz, lower than either the 200 Hz or the 300 Hz component. The two waves return to their starting phase at the same time after three periods of the 300 Hz wave and two periods of the 200 Hz wave; this time is 0.01 second, corresponding to a frequency of 100 Hz. Here is the first hint of a crucial issue, one that extends to theories of music and hearing. If any single pitch can be associated with this combination, it is certainly 100 Hz, but there is no 100 Hz frequency present at all. One can also easily “hear out,” as it is called, the 200 and 300 Hz “atomic” components as individual sinusoidal pure tones embedded in the “molecular” whole. There is much more evidence to present regarding pitch perception, and we leave this subject for a full discussion in chapter 23. — Eric J. Heller, Why You Hear What You Hear- An…, 323 (#expands, via linked claim)

Categorization

• XREF: connects to: Combination tones arise from the hearing system’s own nonlinearity — Professor Dr.-Ing. Hugo Fastl, Professor Dr.-Ing. Eberhard, Psychoacoustics- Facts and Models, 430; Combination tones become audible only above roughly 70 dB primary level; Cancellation equalizes internally produced combination tones with an external tone (+16 more)

Related

• A combined waveform can produce a perceived pitch absent from its actual frequency components (similarity 0.90)
• Combination tones become audible only above roughly 70 dB primary level (similarity 0.88)
• Combination tones fill in missing harmonics of a perceived fundamental (similarity 0.86)
• Two simultaneous tones generate audible lower tones absent from the stimulus (similarity 0.86)
• A perceived pitch can exist with no partial at its own frequency. (similarity 0.85)
• Cancellation equalizes internally produced combination tones with an external tone (similarity 0.85)
• Combination tones beat against other near-pitched instruments unless masked (similarity 0.85)
• Two frequencies can mechanically generate sum and difference frequencies in the ear (similarity 0.85)
• The ear perceives a virtual pitch not physically present in a sound’s components (similarity 0.84)
• Only some combination tones are readily perceived, and none by all listeners. (similarity 0.84)
• A bell’s perceived pitch is usually absent from its actual partials (similarity 0.84)
• The ear generates audible combination tones not present in the stimulus (similarity 0.84)
• Even nonperiodic noise sounds convey a weak pitch sensation based on spectral energy distribution (similarity 0.84)
• Pure-tone instruments readily produce audible combination tones (similarity 0.84)
• Two inaudible high tones can produce audible low phantom tones that interfere (similarity 0.83)

Broader Connections

• A combined waveform can produce a perceived pitch absent from its actual frequency components #expands (0.90) — Eric J. Heller, Why You Hear What You Hear- An…, 323