Measured instrument spectra blend source harmonics with resonance modifiers

Evidence

An important point to note is that this is the spectrum of the output from the instrument, and therefore it includes the effects of the sound modifiers (e.g., air and plate resonances), so harmonic amplitudes are affected by the sound modifiers as well as the sound source. Also, the fifteenth and twentieth harmonics are nearly 40 dB lower than the low harmonics in amplitude, and therefore background noise will have a greater effect on their amplitudes. The guitar spectrum also suggests particularly clearly a pluck point at approximately one sixth of the string length, given the dips in the amplitudes of the sixth, twelfth and eighteenth harmonics. — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 1129

An important point to note is that this is the spectrum of the output from the instrument, and therefore it includes the effects of the sound modifiers (e.g., air and plate resonances), so harmonic amplitudes are affected by the sound modifiers as well as the sound source. Also, the 15th and 20th harmonics are nearly 40 dB lower than the low harmonics in amplitude and therefore background noise will have a greater effect on their amplitudes. — David Howard, Jamie Angus, coustics and Psychoacoustics, 1157

Categorization

• XREF: Shows how a single acoustic feature (pluck position) writes itself across an entire harmonic spectrum — connects to the earlier source/modifier/filter sound modeling framework, and to how readable physical causes leave fingerprints in output.
• DEFINE: Clarifies that an instrument’s recorded spectrum is source-plus-modifier, not pure source — a foundational distinction for psychoacoustic analysis.
• corroborated: 2 independent passages support this claim — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 1129; David Howard, Jamie Angus, coustics and Psychoacoustics, 1157