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Sound Wave Amplitude and Loudness
Transcript of Sound Wave Amplitude and Loudness
This presentation will try to explain the difference between amplitude and loudness for sound waves.
There is a sound test at the end where you can see if different frequencies appear to be louder than each other.
Generally for a sound wave, as the amplitude becomes larger, the sound appears to be louder.
However, amplitude is something that is measurable by a computer and loudness is our perception of that.
"Sound is a mechanical wave that is an oscillation of pressure transmitted through some medium (like air or water)"
Sound can be represented as a transverse wave
For sound, the amplitude is a measure of the extent that the air compresses and rarefies as the sound travels through the it.
Experiments have been conducted which tested our perception of loudness for different frequencies.
These are often called Fletcher-Munson Curves after the people who first created them.
An equal-loudness contour is a measure of sound pressure (dB SPL), over the frequency spectrum, for which a listener perceives a constant loudness when presented with pure steady tones.
As a rough test of how we perceive loudness with different frequencies I created a sound file which includes 9 pure sine wave notes at 9 different frequencies. The amplitudes of the notes are the same.
The notes correspond to the notes C , C etc upto C .
The frequencies (Hz) of the notes are -
C - 16.35
C - 32.70
C - 65.41
C - 130.81
C - 261.63
C - 523.25
C - 1046.50
C - 2093.00
C - 4186.01
Move to the next frame to play the notes
Did you perceive a difference in loudness?