A person standing 1.15 m from a portable speaker hears its sound at an intensity of 6.70 ✕ 10−3 W/m2. HINT (a) Find the corresponding decibel level.   Don't confuse intensity with intensity level. Intensity is a physical quantity with units of watts per meter squared. Intensity level, or decibel level, is based on the logarithm of a ratio of intensities and gives an approximate measure of our perception of loudness. dB (b) Find the sound intensity (in W/m2) at a distance of 39.0 m, assuming the sound propagates as a spherical wave.   W/m2 (c) Find the decibel level at a distance of 39.0 m.

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Interference of sound

Seiche

A seiche is an oscillating standing wave in a body of water. The term seiche pronounced saysh) can be understood by the sloshing of water back and forth in a swimming pool. The same phenomenon happens on a much larger scale in vast bodies of water including bays and lakes. A seizure can happen in any enclosed or semi-enclosed body of water.