The use of reflected SOUND WAVEs for obtaining environmental information. Certain animals, such as the bat and the porpoise, emit pulses of extremely high frequency sound (up to 50 kHz for bats, and up to 170 kHz for porpoises and whales) in narrow, intense streams. The REFLECTION, or ECHO, of these sounds supplies information regarding the nature and location of objects in the environment. When an emission of varying frequency is used, such as with bats, the echoes, travelling varying distances to the ear, are heard as different frequencies in each ear, thus supplying directional information.
A segment or sequence of segments of MAGNETIC TAPE which have been SPLICEd end-to-end to form a loop or circle. When played in this form, the taped sound is continuously repeated, as distinct from tape ECHO or tape FEEDBACK.
The FREQUENCY content of a sound or audio SIGNAL, often displayed as a graphic representation of amplitude against frequency. The spectrum of a sound is a primary determinant of its perceived TIMBRE.
The subjective impression of FREQUENCY, in the same sense that LOUDNESS is the subjective sense of the INTENSITY or AMPLITUDE of a sound. As such, pitch is a psychoacoustic variable, and the degree of sensitivity shown to it varies widely with people. Some individuals have a sense of remembered pitch, that is, a pitch once heard can be remembered and compared to others for some length of time; others have a sense of absolute pitch called PERFECT PITCH.