Science of Sound: 6. Phase

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6 Phase

Phase is the fraction of a complete wave cycle elapsed as measured from a specified reference point and often expressed as an angle. Sound is cancelled (eliminated) when two sounds are presented at 180 degrees out of phase.
SOS Phase
180 degrees out of phase
When two sound waves are “180 degrees out of phase” they cancel each other out and there is no longer any sound at that frequency.
Phase adding waves

Would you be able to hear the result of adding these two sound waves together?

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Tuning fork iconSound is made when an object vibrates the air (or other medium) around it. When these vibrations reach our ear, our brain interprets them as “sound.”

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Soundwave iconWhen sound causes air molecules to vibrate, it compresses and expands the air, forming pockets of high and low pressure. We call them sound waves because the air pressure goes up and down in a repeating pattern.

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Reflection iconWhen a sound wave meets a new material, it is reflected, diffused, absorbed, or transmitted. As sound travels in an environment without obstacles, the sound pressure level will decrease.

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Sound frequncy iconSound frequency is a measure of how quickly the pressure changes, and is measured in Hertz (Hz). Objects that vibrate faster produce higher frequency sounds, and objects that vibrate slower produce lower frequency sounds.

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Sound amplitude iconSound amplitude measures the amount of energy in a sound wave, and is measured in decibels sound pressure level (dB SPL). Sounds with higher amplitude have a greater amount of sound pressure.

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Phase iconPhase is the fraction of a complete wave cycle elapsed as measured from a specified reference point and often expressed as an angle. Sound is cancelled (eliminated) when two sounds are presented at 180 degrees out of phase.

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