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When sounds are conducted separately and independently to each ear via tubes or headphones, the sounds are said to be heard dichotically. In various psychoacoustic experiments, isolation of the function of each ear is desirable, such as in the testing or simulation of BINAURAL HEARING with the PRECEDENCE EFFECT, or in testing preferences for different sounds presented simultaneously to separate ears.
The difference in SOUND PRESSURE LEVEL between the saturation or overload level and the BACKGROUND NOISE level of an acoustic or electroacoustic system, measured in DECIBELs. This RANGE may be expressed as a SIGNAL-TO-NOISE RATIO for maximum output.
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.
The atmosphere exerts pressure on all objects in it. When a vibrating body moves in air, it creates slight disturbances of the AMBIENT atmospheric pressure. The AMPLITUDE of these pressure variations is called the sound pressure variation, whereas the effective pressure variation is 0.707 the maximum value. The oscillating variations in sound pressure (called the WAVEFORM of the sound) PROPAGATE in the form of a SOUND WAVE.