eli5 How do “volume boost” feature work in apps?


How does the volume boost feature in apps like podbean and other podcatchers work? What is it doing or telling the phone operating system to physically do ? And is it just tricking me into thinking it’s louder by initially lowering the max volume then just allowing the max volume to go through when the button is pushed ?

In: 6

>is it just tricking me into thinking it’s louder

No, it is *actually* making it louder – sometimes.

Basically it’s looking at the sound at any instant and if the “total sound” is quiet, it turns up the volume. And when the “total sound” is louder, it turns it back down again. In realtime.

The complexity of what they do can vary dramatically. Sometimes it’s nothing more than applying a formula to the entire sound to produce a number and then adjusting the output so that the number is whatever you selected on the volume knob. Sometimes it’s more complex and does different things at different frequencies. For instance, at very quiet levels your ear loses sensitivity to low and high frequencies, so if you turn down the level it might respond by boosting those frequencies and leaving the mids alone. That’s how the [loudness button](https://en.wikipedia.org/wiki/Loudness_compensation) you used to see on stereos used to work.

The overall concept is known as “[dynamic compression equalization](https://mynewmicrophone.com/the-complete-guide-to-dynamic-equalization-eq/#A-Quick-Discussion-On-EQ)”.