Sound is produced in the larynx; filtering it in the vocal tract produces formants and phonemes. The acoustics, mechanics and some neurobiology of hearing. Pitch perception.
Superposing waves with different frequencies gives beats and Tartini tones. Removing beats gives consonance. Tuning consonances gives temperament.
Frequency, amplitude, envelope and spectrum affect pitch, loudness and timbre. All are discussed and quantified here.
Sound is a longitudinal wave of variations in pressure and density. We derive and measure its speed.