Amr File Extension
Amr is an extension of compressed audio file formats. It can be used by Quicktime software.
Adaptive Multi Rate is a compressed audio file. You may use Quicktime player to open this file format.
Also you have chance to convert this file to different audio format by using AMR converter.
If you need yo cut or combine the audio files we can recommend you C_edit software that is definitely worth to try.
What needed to Open Amr file extensions.
Links about Amr file extension