How to jitter sound?

I’m looking for some ways to edit sounds to be used in game engines and one way could be jittering sound or somehow lower quality of sound, to make effect of simple speaker… I tried to convert sound to PCM 16bit raw format and play with bytes by Hex editor, but since Audacity is clever enough to recover original data by auto swapping endianess mode, I’m looking for a way using features of Audacity to databend the sound. It should sound like from PC speaker or somewhat damaged speaker, I don’t know how to label it correctly. If you play some videos on YouTube in low quality, (simply 240p or lower), most of them will have sound made to highs mostly and it sounds that weird like it was recorded by poor quality mic… 3GP videos have this characteric 8 kHz samplerate sound. When I play 8 kHz in Audacity, it’s made more to lowers than highs. Any ideas how to deal with it?

A lower sample rate simply limits the high frequencies.* Lowering the bit depth will add some quantization noise.

I think what you are looking for are lossy compression artifacts. Try exporting to a low-bitrate constant-bitrate MP3 settings. If you don’t want MP3, you can re-open and re-export to your desired format.

If you want plain-old distortion (clipping), boost the volume (maybe boost for a New Peak Amplitude of +12dB to start… That may be too much distortion, but it should be noticeable). Then export to WAV.

In either case, re-open the file to hear the “real damage”.


Jitter is time-variations in the clock (where for example where the 8kHz or 44.1kHz clock “wobbles around”). It’s analogous to wow and flutter in analog systems, but It is never audible in any digital system unless it’s artificially generated or the system is horribly defective.

I tried to convert sound to PCM 16bit raw format and play with bytes by Hex editor, but since Audacity is clever enough to recover original data by auto swapping endianess mode.

No. Audacity doesn’t do anything “clever”, especially with RAW files. With a hex editor, you could also alter the bytes in a WAV file. Do you have a way of messing up millions of bytes with hex editor? I’ve only used a hex editor to change a few bits manually…

If you want to swap the bytes, you can simply enter the wrong setting when you open the RAW file. But that’s going to give you almost pure noise, which is more damage than you want to do. You can also screw-up the byte order by entering the wrong offset. Changing the offset by 1 will destroy the data. (with 24-bit files, you can change the offset by 1 or 2 to foul thing’s up.) Of course, with 8-bit files (where each sample is one byte) you can’t change the byte order.


  • It can also cause aliasing if not filtered correctly, but I don’t know of an easy way to turn-off the filtering which is part of any proper sampling system or resampling algorithm.

Okay, exported to 8bit signed PCM and played around with bytes in hex editor. Swapped 4 to 4 bytes and this gave me that jittered sound I was looking for :slight_smile:

If you do not know how it sounds alike, try to load up your favourite song in Audacity, convert to 8bit signed PCM raw file, open by your hex editor (Hexplorer is one of main favourite), use to swap 4 to 4 bytes (in hexplorer it’s labeled swap bytes 64bit), save as raw file and load it again in Audacity (possibly mute the original one). Click play and listen. One game developer used that effect to make player model thirsty (weird, I know, but that’s it) :slight_smile:

I would use this technique in my game develope projects not to make player thirtsy like the one I wrote, but make ambient sound of broken radio speaker or something similar tech… Thank you for your advice, I think this thread can be closed :slight_smile:

Audacity does offer phone codecs [like AMR and GSM] if you install FFmpeg …[u]How_do_I_download_and_install_the_FFmpeg_Import.2FExport_Library[/u].3F