Describing Sound Waves (Chapter 3)

Vocabulary flashcards covering key terms related to describing sound waves, including period, frequency, their relationship, amplitude, power, intensity, and the frequency ranges of infrasonic, audible, and ultrasonic sounds.

Period (T)

Time required for one complete cycle of a wave; interval from the start of one cycle to the start of the next. Units include microseconds, seconds, hours, days; determined by the sound source.

Frequency (f)

Number of cycles that occur in one second; units are Hertz (Hz); f = 1/T; typical ultrasound values: about 2 MHz to 15 MHz; ranges include Infrasound (

Inverse relationship between Period and Frequency

Period and frequency are reciprocal: T = 1/f; as one increases, the other decreases.

Amplitude

Magnitude or 'bigness' of a wave; difference between the minimum value and the average value of an acoustic variable; units depend on the variable (e.g., Pascals, cm); generally determined by the sound source and may decrease as the wave propagates; adjustable.

Power

Rate at which energy is transferred by the wave; unit: Watts; typical values roughly 0.004–0.090 W (4–90 mW); determined by the sound source; adjustable; increasing power increases amplitude.

Intensity

Concentration of energy in a sound beam; unit: W/cm²; determined by the sound source; adjustable; typical range about 0.01–300 W/cm².

Infrasound

Frequencies below 20 Hz; not audible to humans.

Audible range

Frequencies from about 20 Hz to 20 kHz; audible sound.

Ultrasound

Frequencies above 20 kHz; used in medical imaging; typically in the MHz range (e.g., ~2–15 MHz).