Convert AMR to MP3
AMR is the GSM speech codec - narrow-band (AMR-NB) or wide-band (AMR-WB). Older Android and Nokia phones wrote voice memos and MMS voice clips as .amr files. Wave decodes them and re-encodes to a portable MP3 through libmp3lame. Modern voice recordings are usually Opus instead - see Audio codecs explained for the current speech-codec landscape.
What actually changes
AMR (Adaptive Multi-Rate) is the audio codec of GSM voice channels - the same encoder that compresses your voice on a phone call travelling over a European or Australian 3G network. AMR-NB (Narrow-Band, 4.75-12.2 kbps at 8 kHz sample rate) was the original 1999 codec; AMR-WB (Wide-Band, 6.6-23.85 kbps at 16 kHz) added in 2001 gave "HD Voice" quality on modern networks. Older Android phones (2007-2013) wrote voice memos as .amr, Nokia's Series 40 and Series 60 devices wrote MMS voice clips as .amr, and many voicemail archive tools export as .amr.
Wave decodes AMR through ffmpeg-wasm's AMR-NB and AMR-WB decoders (both are bundled) and re-encodes to MP3 at 192 kbps VBR through libmp3lame. Because AMR is a heavily bandwidth-limited speech codec, the source is already at telephone-audio quality; the MP3 preserves every audible sample but stays bandwidth-limited (the source, not the target, sets the ceiling).
AMR's bandwidth constraints are worth understanding. AMR-NB carries voice frequencies from about 200 Hz to 3.4 kHz - the classic telephone-audio range designed to preserve speech intelligibility with minimum bandwidth. Music, background sound, and anything outside the voice band gets aggressively cut. AMR-WB extends the top end to about 7 kHz, capturing more of the character of voices without adding proportional file size. The MP3 output at 192 kbps VBR gives LAME far more bit budget than the source needs; the file is bigger than the AMR (typically 10x-20x) but the audio is preserved.
The typical use case for converting AMR to MP3 is archive portability. Voice memos and voicemail archives that landed as .amr in the 2007-2013 mobile-phone era don't play in modern podcast apps, music players, or audio-editing tools without a converter step. MP3 plays everywhere. Wave's conversion is the fastest and most private way to convert them - especially since the audio content is often personal (family recordings, voicemails, oral histories).
Three steps.
-
01
Step 1
Drop the .amr file onto the card.
-
02
Step 2
Wave inspects the source and confirms Decode-and-re-encode.
-
03
Step 3
Convert. Save the MP3.
Answers, specifically.
AMR-NB vs AMR-WB support?
Both. Wave inspects the source and picks the right decoder. AMR-NB is more common in older files; AMR-WB in newer ones.
Will the MP3 sound "phone-quality"?
Yes. AMR caps the source at telephone-audio bandwidth; the MP3 preserves that limit. Playing the output on studio monitors will sound the same as playing the original AMR through phone speakers.
Old Android voice memos?
Yes. Android's stock voice recorder wrote AMR as its default format on many devices through 2013. Wave handles those cleanly.
Nokia MMS voice clips?
Yes. Nokia Series 40 and Series 60 devices used AMR for MMS voice attachments. The saved .amr files decode normally.
Voicemail archive tools that export AMR?
Yes. Where you can get the raw .amr file (some Verizon and T-Mobile visual-voicemail exports produced them), Wave converts them.
File size after conversion?
The MP3 is typically 10-20x larger than the AMR - the format is much more verbose - but audio content is preserved. A one-minute AMR-NB voice memo at ~50 KB becomes an ~800 KB MP3.
3GPP file with AMR audio?
3GPP is a video container; use the 3GP to MP3 page for those files. The .amr extension is specifically for raw AMR audio outside a container.