Exporting m4a as mono is 160 kbps no matter what

I’m deaf in one ear so I like having my music in mono but i just tried to export m4a as mono and it was 160 even though i set it to 256, does anyone know a work around? ill go back to mp4 if i have to but i wanted to save space on my phone

I can confirm …

~160kbps is as high as that codec goes for a mono recording.
256 kbps, if it were possible, is overkill for a mono recording, (stereo is another matter).

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160 kbps is equivalent to 320 kbps for stereo. This is as high as the export goes; though the UI does lie to you when you enter higher numbers as it doesn’t check whether you’re mono or stereo.

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I didn’t know that but thank you so much, it was driving me crazy but yes about 160, i have audio anywhere from 150-170 but i thought it was weird it didn’t go higher, then when i realized 160 is half 320 i thought i was dividing the audio and giving me a half

Incidentally I came across this not too long ago that gives a good estimate for what bitrates give a comparable quality level across different numbers of channels (assuming a codec like AAC or Opus). Basically, rather than a linear relationship, it’s based on channels raised to 0.75 (since there’s a lot of overlap in the signals between channels that those codecs can exploit).

So 160 kbps mono would be comparable in quality to 269 kbps stereo (160×20.75≈269). And stereo AAC at 256 kbps or above is generally considered “transparent” (which means virtually no one can hear the difference from the original in blind listening tests).