Functions to interact with the audio mixer.

The audio mixer service reads audio mixer change events, such as when the volume level or gain of mixer channels changes. You can also use the audio mixer service to set and get different audio attributes, such as volume, gain, and mute status.

For example, using the audio mixer service allows an application to receive notifications when a headset is present, or when the speaker volume is muted. The application can also set headset volume, speaker volume, and so on.