To start using Sound Amplifier plug in wired headphones (required) then go to Settings > Accessibility > Sound Amplifier.

Sound Amplifier enhances audio from your Android device using headphones to provide a more comfortable and natural listening experience. Use Sound Amplifier on your Android device to filter augment and amplify sound in the real world. Sound Amplifier makes audio clearer and easier to hear. It works by increasing quiet sounds while not over-boosting loud sounds. With 2 simple sliders you can quickly customize sound enhancement and noise reduction to minimize distracting background noise.

Features
• Boost quiet and reduce loud sounds around you and on your device.
• Carry on conversations in loud environments.
• Personalize your listening experience by adjusting audio or microphone settings with the simple tuning UI.
• Reduce unwanted or distracting noises.

Once you’ve tuned Sound Amplifier to a setting you like you can toggle it on and off using the Accessibility Button.

Permissions Notice
• Phone: Needed to know the phone state to pause Sound Amplifier when there’s an incoming or outgoing call.
• Microphone: Needed for real-time audio processing.