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FletcherMunson Curve

>> This graph was established in the 1930's after human research by Fletcher and Munson determined how variations in the perceived loudness of sounds changes with sound frequency.

You will notice that lower frequency sounds (on the left above) have to be much louder than sounds in the 4 to 16 kilohertz range in order for them to perceived at the same level.

This graph explains one of the banes in watching old movies on TV. Old films with their early optical sound tracks have a limited high frequency response (largely in the middle of the graph above), but the commercials, which are done with newer and better equipment, contain higher frequencies (on the right side of the curves above) and, overall, seem much louder. However, with the standard VU audio meter used in TV stations the sound levels on the films and the commercials may register at the same level.

To compensate for this perceived difference many TV stations now use audio processing equipment that takes into consideration the above relationships and evens out the perceived audio level differences. In case your local station doesn't do this, it's possible to buy an audio device for your home theater equipment that will do it for you.

TV Production Index

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