Distorted playback...sometimes

[wspencer11]

Hi there: I'm using version 2.3.2 in OS 10.15.6 and am finding that if I play back a song using Audacity it sounds fine but if I play back the exact same file using Apple Music the loudest bits get some crackly distortion--sometimes, not always. I tried reducing the playback volume in Music but that made no difference, the crackle only got softer. Not all loud parts get distorted, only certain ones. Any theories on why this would happen? Thanks in advance!

[DVDdoug]

Do you have clipping?

Are you mixing? Mixing is done by summation so the exported mix can clip even if the separate files don't.

if I play back a song using Audacity it sounds fine but if I play back the exact same file using Apple Music the loudest bits get some crackly distortion

Audacity uses floating-point temporarily/internally so Audacity itself can go over 0dB without clipping. You'll clip your digital-to-analog converter if you play-back at "full digital volume" but you might not hear it if you play at lower volume.

If your audio goes over 0dB and you export as "regular WAV", the file will be permanently clipped (distorted). Some formats can go over 0dB but it's "bad practice" to make such a file because the listener's DAC can clip when the file is played.

[wspencer11]

Audacity does not find clipping in the file I'm working on, and the file is not mixed, it's a straight recording via a Zoom H2N recorder. I normalize the WAV file to boost levels to the preferred max (-3db is the top limit I set). If I then export the result as a 256k MP3 or as a regular WAV I get the same result.

[kozikowski]

Are you recording audiobook chapters?

Are you using Audacity Audiobook Mastering?

https://wiki.audacityteam.org/wiki/Audiobook_Mastering

This is the abbreviated version.

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If you're recording at home, it's good to use all three of the steps. The first one is a rumble filter and its job is to get rid of very low pitch sounds that can cause troubles even if you can't hear them. Many home microphones have this problem.

Koz

[kozikowski]

Select, export WAV, and post ten seconds of a passage that causes troubles.

Scroll down from a forum text window > Attachments > Add Files.

Koz

[wspencer11]

The issue happens around 7-8 seconds in.

[kozikowski]

It's rich in overtones and slightly higher volume right there, but I don't hear anything wrong.

Can you play it in QuickTime?

Koz

[kozikowski]

There is one. There is high pitched, crisp sound really close to the digitizing limit of 44100.

Apply Effect > Low Pass filter.

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See what happens.

Koz

[wspencer11]

Haven't tried QuickTime, as I noted the problem seems to be within Apple Music specifically...I'll check QT.

[wspencer11]

Sounds fine in QT also. Could you please explain the tool you posted? Low-pass filter, I think it was. I am not at all an expert in any of this, just an occasional hobbyist user.