AMR and MP3 explained
AMR is a narrowband speech codec designed for mobile phone calls. It is optimised specifically for the frequency range of the human voice and sounds poor for anything else.
MP3 is the lossy audio format that made digital music portable. Its patents expired in 2017, which is part of why it remains ubiquitous — anyone can implement it freely.
- Where AMR files come from
- Voice memos and voicemail from older phones.
- Where MP3 is used
- Music libraries, podcasts and voice recordings.