isacoustic

isacoustic 1. Applied to a curve passing through those points (in a theater, concert-room, etc.) at which a speaker or performer may be heard equally well. 2. In seismology, applied to a line (imaginary or on a map) connecting places where an equal percentage of observers heard the sound of an earthquake.
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isacoustic

line connecting points of equal acoustic quality
Found on http://phrontistery.info/i.html
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