Convert audio to M4A

In the Music app, select the song and choose File → Convert → Create AAC Version. For files anywhere, the built-in afconvert tool does it in one line: afconvert -f m4af -d aac turns a WAV or AIFF into an .m4a a fraction of the size.

How

Convert one file:

afconvert -f m4af -d aac recording.wav recording.m4a

Convert every WAV in the folder:

for f in *.wav; do afconvert -f m4af -d aac "$f" "${f%.*}.m4a"; done

Or just ask Titan

Convert the voice memos in this folder to M4A so they’re small enough to send. Do it with Titan

Titan is an AI that lives on your computer: tell it what you need and it does it while you watch — you press Return, nothing runs by itself. What is Titan?

Titan isn’t on this computer yet. Get Titan, then press the button again — the task will be waiting, typed in.

Related

Get the audio out of a video Turn text into a spoken audio file