16-bit 'downgrade' filter? (Need some help/advice)

Special Interest Groups Audio Processing
1

Hello all,

I’m in the process of composing a score for a fan-made game, and my client is asking for the songs to sound like it’s from a 16-bit system – think SNES or Genesis or something along those lines. The problem is, all my instrument samples are “realistic” – ie. they sound too “good” for what he’s looking for (and yet he doesn’t want straight MIDI, because that sounds like garbage). So here’s my question: Does Audacity have some kind of filter or other effect that would allow me to pass the sound that I have, and make it sound 16-bit on the other side? If not, does anyone have any suggestions as to how I can accomplish what he’s asking for? I’ve tried looking around for sound fonts, to no avail. I’m using Audacity 1.3, and for composing I’m using Cakewalk Music Creator 4. Any help is greatly appreciated. Thanks!

2

I think you need to reduce the sample rate rather than the bit depth to produce poorer sound quality.

If you reduce the sample rate to 8000Hz the sound quality is like that of a telephone, (frequencies above 4000Hz are lost).

In Audacity 1.3 click on “Tracks”, “Resample” then select a lower sample rate, (e.g. 8000), also change the project rate (bottom left) to 8000.

Be careful to save this poor quality version under a different name so you still have the high quality original.

3

Rather than change the sample rate you could use a narrow band pass filter to achieve the same telephone quality effect ( here is a link to a before after example).

Adding amplitude modulation makes the sound very computer gamey ( here is a link to a modulated version of the above example)

You can modulate one sound with another using the Nyquist code here.