Even steady musical notes constantly change in their sound

Evidence

The sound of an acoustic musical instrument is always changing, even during the rather misleadingly named steady-state portion of a note. This is clearly shown, for example, in the waveforms and spectrograms for the violin and sung notes in Figure 5.5. Pipe organ notes are often presented as being “steady” due to the inherent airflow regulation within the instrument, but Figure 5.1 shows that even the acoustic output from a single organ pipe has an amplitude envelope that is not particularly steady. This effect manifests itself perceptually extremely clearly when attempts are made to synthesize the sounds of musical instruments electronically and no attempt is made to vary the sound in any way during its steady state. — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 1485

Categorization

• XREF: Illuminates why electronic synthesizers that hold a perfect steady state sound artificial — and why the natural, always-changing quality of acoustic sound marks humanness in audio.