pitch and frequency ..........

pitch

Pitch is an auditory sensation: when we hear a regularly vibrating sound such as a note played on a musical instrument, or a vowel produced by the human voice, we hear a high pitch if the rate of vibration is high and a low pitch if the rate of vibration is low. Many speech sounds are voiceless (e.g. [ s ]), and cannot give rise to a sensation of pitch in this way. The pitch sensation that we receive from a voiced sound corresponds quite closely to the frequency of vibration of the vocal folds; however, we usually refer to the vibration frequency as fundamental frequency in order to keep the two things distinct. Pitch is used in many languages as an essential component of the pronunciation of a word, so that a change of pitch may cause a change in meaning: these are called tone languages. In most languages (whether or not they are tone languages) pitch plays a central role in intonation.

fundamental frequency

When voicing is produced, the vocal folds vibrate; since vibration is an activity in which a movement happens repeatedly, it is possible in principle to count how many times per second (or other unit of time) one cycle of vibration occurs; if we do this, we can state the frequency of the vibration. In adult female voices the frequency of vibration tends to be around 200 or 250 cycles per second, and in adult males the frequency is about half of this. It is usual to express the number of cycles per second as Hertz (abbreviated Hz), so a frequency of 100 cycles per second is a frequency of 100 Hz.

Why "fundamental"? The answer is that all speech sounds are complex sounds made up of energy at many different component frequencies (unlike a "pure tone" such as an electronic whistling sound); when a sound is voiced, the lowest frequency component is always that of the vocal fold vibration - all other components are higher. So the vocal fold vibration produces the fundamental frequency. See also pitch.