An audio amplifier is a device that makes sound louder. It takes the quiet sound from a source like a music player or a microphone, and then increases the volume so you can hear it better through speakers or headphones. Full definition
Adaptive audio amplifier, Android Sensor Hub, Wireless Emergency Alerts function, Google Caller ID, HD Voice, Knock Knock function, MIMO technology, Quick Switch function, RGB LED notification light, Three microphones with noise cancellation, Wi - Fi Calling (cnet.com)
We found not just 2 but 3 Audio Amplifiers - we speculate there is one audio amplifier for for each of the two speakers, and the third amplifier is for the headphone via the Lightning port. (macrumors.com)
The phone features a smart audio amplifier with dual speakers and Dolby Atmos sound. (technewsworld.com)