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Old 7th June 2015
matt thomas's Avatar

Originally Posted by miguellacorte View Post
I have a question about compressing. Why does is sometimes outputs more volume? i mean, isn't the the compressor's job to lover the volume of the signal? i know that The threshold will be the "ceiling" that will determine the compressor when to lower the volume, and the ratio will determine how much to lower it. for example in a vocal, i thought that the compressors job was to lower the highest peaks, but is it actually to average the difference between the lowest signal and the highest?

is this true?: the compressors outputs more volume because it sometimes doesn't lower the highest peaks, but rather, make the lowest peaks be more hearable.
Essentially, it lowers the highest peaks/parts (those above the threshold). After you have done this, you are able to turn the signal up louder, without the highest peaks clipping, or being otherwise too high any more. So yes, it does reduce the dynamic range, but you can then use make up gain to restore or boost the level. In the end you have increased the average level, and the human ear here's the average level, not the peak level, so it sounds louder.

Image you have the numbers:


You want to make these louder on average, but you can't go above 10, so you limit these (compress them) to 5, and you have


You can then turn them all up (in this case double them) to


the average level was 5.5, but it is now 8, and you still don't go above 10

(all simplified obviously)