A single amplitude envelope cannot capture how separate spectral parts evolve

Evidence

The amplitude envelope is not sufficient to represent the behaviour of different spectral parts of the sound produced by many musical instruments. The spectrogram (see Section 3.2.6) can be used to visualize instrument sounds. Figure 6.5 shows the magnitude envelopes of the harmonics of a kantele, a Finnish plucked string instrument. The plot shows the typical characteristics of the kantele sound; it has strong decay at higher harmonic partials, and it also has strong amplitude modulation at the harmonics, which appears with different modulation frequencies for different harmonics. — Ville Pulkki, Matti Karjalainen, Communication Acoustics- An…, 687

Categorization

Category: Definitional Content

• DEFINE: Clarifies why spectrograms rather than simple envelopes are needed: harmonics decay and modulate independently of one another.
• XREF: Connects to spectrogram/short-time Fourier transform analysis methods and to the physical modeling of plucked strings in audio synthesis.

Related

• A single amplitude envelope misses that harmonics decay and modulate at different rates (similarity 0.91)
• Amplitude-modulated sounds split into slow-varying envelope and fast-varying fine structure (similarity 0.81)
• Temporal change is a defining feature of natural sound perception (similarity 0.81)
• Perceived instrument character is shaped by the time evolution of sound amplitude (similarity 0.80)
• Spectrograms require intensity maps or waterfall plots because they are three-dimensional (similarity 0.80)
• Measured instrument spectra reveal both the source and the sound modifiers at once (similarity 0.80)
• Every stringed instrument is analyzable as a sound source plus modifiers (similarity 0.79)
• Spectrograms plot frequency against time to show both at once (similarity 0.79)
• A spectrogram displays a sound’s spectrum plotted against time (similarity 0.79)
• Spectrogram gray-scale plots show how a sound’s spectrum changes over time (similarity 0.79)
• Peak amplitude misrepresents complex sounds with varying amplitude (similarity 0.79)
• Two kinds of sound change activate different processing features in hearing (similarity 0.79)
• A stringed instrument’s pluck position can be read from harmonic amplitude dips. (similarity 0.79)
• Musical instrument sounds divide into attack, decay, sustain, and release phases (similarity 0.78)
• Hearing is highly sensitive to temporal changes in sound (similarity 0.78)