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Frequency measures how many complete wave cycles occur per second, in hertz

Fact L1Foundations B · Sound design & synthesis

Frequency is the number of complete pressure oscillation cycles a sound wave completes per second, measured in hertz (Hz) or cycles per second. A cycle consists of one full compression-rarefaction sequence. Period T (in seconds) is the inverse of frequency: if T = 0.01 s, then f = 100 Hz. Audible frequencies range from about 20 Hz to 20,000 Hz; higher frequency corresponds to higher perceived pitch. Wavelength is inversely proportional to frequency: a 100 Hz wave has a wavelength of about 3.44 m at room temperature (speed of sound ≈ 344 m/s). This relationship matters for physical synthesis and room acoustics.

Examples

Middle A (A4) = 440 Hz, meaning 440 complete pressure cycles per second. An octave above (A5) = 880 Hz — twice the frequency, half the period.

Assessment

If a sound has a period of 0.005 seconds, calculate its frequency in Hz and describe its approximate pitch relative to a piano keyboard.

Prerequisites — understand these first

Sound waves are pressure variations in air that the cochlea decodes as electrical signals

Sources

“The number of cycles that are completed in a second is defined as frequency, and is measured in hertz (Hz) or cycles per second (cps).”

corpus · electronic-music-and-sound-design-vol-1-cipriani-and-giri-of · chunk 7

Taught in modules

How sound works: pressure, spectrum, and the anatomy of a tone

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