What is quality of sound in physics?

The Word "quality" is unlikely to be used in physics because it is not an objective, measurable characteristic. Acoustics (the physics of sound and vibration) analyses sounds to determine their spectra, and measures their overall intensity and power, but I have never seen 'quality' used in a formal sense.

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I suppose it may come into architectural acoustics, which would no doubt cover at least absorption, echoes and reverberation with respect to frequency and amplitude in the building under study, but that's not a field with which I am familiar.