Frequency, amplitude, and waveform are the three fundamental parameters of a sound

Every periodic sound can be described by three independent parameters: frequency (which the listener perceives as pitch), amplitude (perceived as loudness or intensity), and waveform (a major determinant of timbre). Changing frequency changes pitch; changing amplitude changes loudness; changing waveform changes the sound’s color while preserving its pitch and approximate loudness. In synthesis, manipulating these three parameters is the primary means of designing a sound. Timbre in practice depends on additional factors (envelope shape, harmonic relationships), but frequency/amplitude/waveform form the essential triad for understanding any waveform.

Examples

A 440 Hz sine wave at amplitude 0.5 has a fixed pitch (A4), medium loudness, and a flute-like timbre. Changing it to a sawtooth at the same frequency and amplitude shifts timbre dramatically while pitch stays the same.

Assessment

Explain why two sounds with identical frequency and amplitude can still sound different, and name the parameter responsible.