It measures the loudest peak and sets the gain so it lands at −1 dBFS: the loudest possible level without clipping.
With that gain some samples go above 100% and get cut off, which sounds distorted. Lower it a few dB or use Normalize.
Yes, the Change audio volume tool is 100% free, unlimited and requires no sign up or installation.
No. Every operation on Toolkoa is processed privately and locally, directly in your own browser.
Nothing to install. Change audio volume runs in any modern desktop or mobile browser, and once the page has loaded you can keep using it without relying on the connection.
