From Applied Voices:
This product should always be used with headphones. Adjust the volume of your friend's voices. Listen to the sound of a pen writing on paper!uListen is an adaptive sound amplifier. Used with headphones, it can make everyday sounds picked-up by your phone's microphone sound louder or softer. This is great for TV sounds, for making friend's voices seem louder or softer, or for listening to sounds around your house.This app can also turn your iPhone into a sound probe that lets you explore the microscale sound world in your home and office. Listen to the sound of a pencil writing on paper, or of an Apple being sliced! Adaptive volume reducer permits you to turn up the amplifier gain to hear soft sounds, without experiencing an unpleasantly loud sound if someone starts talking or a loud sound occurs. This selective amplification mode makes soft sounds louder, while making loud sounds softer. Automatic functions can be switched off, providing direct manual control of amplification level via a thumb slider.uListen is an entertainment application, not a hearing aid. uListen should never be used for medical purposes, and should not be used to receive emergency communications.uListen requires headphones. It works best on iPhone with headphones that do not have a microphone built-in. Use on iPod Touch 2nd generation requires external Apple earbud microphone accessory. iPod Touch 1st generation is not supported.
What's new in this version:
Eliminated all advertising.Compatibility with iPod 4, iPhone 4G, and iPad.Added master volume control sliderAudio latency improvementsGradual ramp-up of volume level when controls are adjustediOS 4.2 compatibility