Amplitude variation can arise purely from pitch change interacting with fixed resonances.

Evidence

However, its origin might not be so obvious, since it needn’t be created by direct changes to the amplitude itself. If the instrument has resonant peaks in the frequency response of its sound modifiers, such as the orchestral string family, in which they are fixed in frequency being based on the instrument’s body (see Section 4.2.4) and the human voice, in which they are the formants that can be changed in frequency and are therefore dynamic (see Section 4.5.2), then a change in the fundamental frequency will produce a change in the overall amplitude of the output. — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 1468

Categorization

• XREF: Ties back to body-based resonances of strings (Section 4.2.4) and dynamic vocal formants (Section 4.5.2) established earlier in the book. — connects to: Amplitude modulation faster than the tone’s own steady pitch is heard as pitch change — Professor Dr.-Ing. Hugo Fastl, Professor Dr.-Ing. Eberhard, Psychoacoustics- Facts and Models, 1138; Shifted complex tone pitch depends on envelope-fine-structure interaction, not fine structure alone. — Dijk, Pim van, Physiology, Psychoacoustics and…, 4659; Pitch differences caused by shifts are not purely fine-structure based (+7 more)
• SEED: Article angle: tremolo you hear isn’t tremolo — how resonance skirts turn pitch wobble into loudness wobble.

Broader Connections

• Shifted complex tone pitch depends on envelope-fine-structure interaction, not fine structure alone. #corroborates (0.95) — Dijk, Pim van, Physiology, Psychoacoustics and…, 4659
• Pitch shifting can alter pitch without changing spectral character. #corroborates (0.95)
• A steady-sounding note still has amplitude envelope variation within it #corroborates (0.95) — David Howard, Jamie Angus, coustics and Psychoacoustics, 1464
• Amplitude modulation faster than the tone’s own steady pitch is heard as pitch change #expands (0.90) — Professor Dr.-Ing. Hugo Fastl, Professor Dr.-Ing. Eberhard, Psychoacoustics- Facts and Models, 1138
• An instrument’s playability depends on many cooperating, accurately tuned resonances #expands (0.85) — Eric J. Heller, Why You Hear What You Hear- An…, 1555
• A single amplitude envelope misses that harmonics decay and modulate at different rates #complicates (0.85) — Ville Pulkki, Matti Karjalainen, Communication Acoustics- An…, 687
• A resonance unsupported by cooperating upper harmonics produces a wobbly, unstable note #corroborates (0.85) — Eric J. Heller, Why You Hear What You Hear- An…, 1558
• Pitch differences caused by shifts are not purely fine-structure based #qualifies (0.80)
• Signals identical in loudness and pitch can differ markedly in pitch strength #complicates (0.80) — Professor Dr.-Ing. Hugo Fastl, Professor Dr.-Ing. Eberhard, Psychoacoustics- Facts and Models, 3289
• Combination tones arise from the hearing system’s own nonlinearity #complicates (0.75) — Professor Dr.-Ing. Hugo Fastl, Professor Dr.-Ing. Eberhard, Psychoacoustics- Facts and Models, 430