The download button opens the iTunes App Store, where you
may continue the download process. You must have iTunes installed with an
active iTunes account in order to download and install the software. This
download may not be available in some countries.
From PINTA-offbeat:
HearAmp emulates the function of an Assistive Listening Device (ALD). It amplifiers incoming sounds received via the phone's microphone using compression amplification technique.
HearAmp for iPhone
