What is a AMR file?
Speech-optimized mobile audio format
AMR was adopted as the standard speech codec by the 3rd Generation Partnership Project Group (3GPP)and is now widely used in GSM and UMTS for 3G mobile phones and devices.
The Adaptive Multi-Rate (AMR) audio file format that is optimized for speech coding. Thus, most audio saved in the AMR file format is compressed and optimized for human speech frequency ranges. Thus, the AMR speech codec consists of a multi-rate narrowband speech codec that encodes narrowband (200–3400 Hz) signals at variable bit rates ranging from 4.75 to 12.2 kbit/s with normal quality speech starting at 7.4 kbit/s. Since it is used mainly for mobile speech communication, it chooses between the 8 different bit rates based on link conditions.
Common uses for AMR files
- Voice recordings on mobile
- Voicemail messages
- GSM phone calls
- Android voice recorders
- Mobile phone voicemail
- 3G phone recordings
Who works with AMR files?
Journalists who record phone interviews, legal and compliance teams reviewing call evidence, and call-center or telecom staff handling carrier voice files encounter AMR regularly. Field researchers and support teams also receive AMR attachments when interviews or messages are captured on older mobile handsets.
AMR vs MP3: which should you use?
AMR is a narrowband speech codec that samples at 8 kHz and encodes at 4.75–12.2 kbps, producing very small files limited to the telephone voice range, while MP3 is a general-purpose audio format supporting higher sample rates and bitrates for music and full-range sound. MP3 also has far broader playback support across devices and software. AMR makes sense when a phone or voicemail system produces it automatically and file size matters; MP3 is the better choice for sharing, archiving, or any audio beyond speech.
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