Android: Intelligent Ringer is a free utility for Android that listens to the ambient noise level in the room around you, and sets your phone's ringer to match. That means you won't scare everyone around you with a loud ringtone in a quiet room, or miss a call because the ringer is set too low and you can't hear it over the noise around you.
Intelligent Ringer is perfect for those situations where you put your phone on silent or vibrate during a meeting, then miss a call later because you forgot to turn the ringer back on. It's also ideal for that coworker who just refuses to turn their ringer down while they're working at their desk. The app is intelligent enough to use the proximity sensor to know if the phone is in your pocket. If you want more control over the app, you can adjust its sensitivity and set the minimum volume.
We covered RingDimmer, a similar app, last year. However, RingDimmer hasn't been updated in a while and costs $1, while Intelligent Ringer is free. Grab Intelligent Ringer from Google Play at the link below.