This is problematic when placing microphones since most engineers want to capture the most genuine sound possible. Since reflected sound is a delayed, filtered copy of the incident sound (initial impulse), there is often phase interference when they collide in the air. Just about every surface, room, and an obstacle in the world reflect sound to some degree. It is often used as an insert effect in electronic production and – because of the peaks and nulls – makes the spectrum appear “comb-like”.Ī relationship between Distance, Delay Time, and Phase It accounts for the majority of interference. In the electronic realm, destructive phase interference is used to remove frequency content from the sound.Ĭomb-Filter – causes a series of alternating constructive and destructive “peaks and nulls” due to irregular phase relationships (between 1-179 degrees and 181-364 degrees). Causes the waves to “cancel each other out”. In the electronic realm, producers often use constructive phase to boost frequencies.ĭestructive – occurs due to phase relationships of 180 degrees. It causes the amplitude to multiply and sometimes resonate. There are 3 types of phase interference…constructive, destructive, and comb-filtering.Ĭonstructive: occurs due to synchronized phase relationships (0 degrees and 360 degrees). It primarily affects amplitude (pressure or power). Every sound in the world can be broken down into its sinusoidal components.Ī phenomenon describing the interactions between two or more nearly identical sounds performed simultaneously. Sine waves are the “cells” that make up a sound. *The sine wave describes the simplest oscillation, one frequency – so simple it does not exist (audibly) in real life, only in electronics and theory. On the other hand, this sine wave is 180 degrees out of phase (½ cycle)įinally, this sine wave is 270 degrees out of phase (3/4 cycle) This sine wave is 90 degrees out of phase (¼ cycle) The best way to convert this basic understanding into a valid, abstract internalization is to think about 2 sine waves*. In my analogy above, the reference would just be the correct version of Twinkle Twinkle Little Star (starting at the beginning). So, you need to know where “0” is to measure phase degree. In order to determine the phase degree, a reference waveform is necessary. Since phase is measured in “degrees” from 0 to 360, I might call the tune something like “Twinkle 120”. If I were to start singing Twinkle Twinkle Little Star from the lyrics “up above the world so high”, it would still be the same song except, “phase shifted” by one third of the total duration. Here is an analogy on a less abstract level… Phase (sometimes called “position”) is the orientation of a cyclical waveform in time, relative to a another cyclical waveform.
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