As depicted in the following diagram, the lower part of the wave corresponds to low air pressure while the higher part of the wave corresponds to higher air pressure. A cycle measures the temporal duration during which the repeatable part of the wave occurs. Frequency is measured by the number of cycles per second. Amplitude is a measure of the maximum air pressure. Timbre is a psychological response to the particular pattern of air pressure variations within a single cycle.

Frequency is measured by the number of cycles, per second, by which a pattern of air pressure changes is repeated. Pitch is a sensation that results from psychological response to frequency. The range of audible frequencies for humans falls roughly between 20 and 20,000 Hz. A Hz (hertz) is a measure of the number of cycles per second.