Rdio Scanner is an open source software that ingest and distribute audio files generated by various software-defined radio recorders. Its interface tries to reproduce the user experience of a real police scanner, while adding its own touch.
There are already many ways to control the volume of a browser tab running a web app, depending on the platform and the browser you are using. Are you asking this because the audio is sometimes too low?
the web app needs the ability to control the volume please