FREQUENCY2
The number of complete cycles achieved by a sound wave in a second. If a plucked violin string vibrates 400 times a second, the frequency of the sound it emits is measured as 400 cycles per second or 400 Hertz (Hz). If the string is tightened, it will vibrate more rapidly, and its frequency will increase. The result is that the pitch of the sound (its frequency as perceived by a listener) will also rise. However, there is not a simple relationship between pitch and frequency: the ear does not judge a sound of 1000 Hz to be twice as high as one of 500 Hz.
The range of frequencies handled by the human ear goes from about 250 to10,000 Hz. Most human conversation occupies a range of between 250 and 8000 Hz. But the frequency band may be narrowed in certain forms of speech transmission (e.g. the telephone), with the result that some of the cues to a particular phoneme may be missing. Especially affected is /s/.
Speech has a fundamental frequency which derives from the tension and speed of vibration of the vocal folds. Other cycles of the sound wave are multiples of this base value. Fundamental frequency or F0 is an important measure in that it serves as a base value for listeners, enabling them to detect pitch movements, which, in English, might mark sentence stress or intonation. Average F0 values vary from voice to voice. Male speakers often have thicker vocal folds than female, so a typical F0 for a man is lower (between 100 and 160 Hz) than that for a woman (200 Hz and above).
See also: Formant, Intelligibility, Speech signal
Further reading: Ball and Rahilly (1999); Denes and Pinson (1993); Gimson (1994); Pickett (1999)
