Scratch up CDs to get a glitch sound
recording music, sound effects, broadcast, CDs.

Michael Oster
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CD Trauma - scratch up your CDs and bask in the glitch!

picture of a scratched up CD

Sorry for the huge picture, but the details are important.

The things we do to screw up audio - like scratch CDs to hell. Scratch up CDs? Yes, you'll get stutters, "jump backs", jitter, scrambled audio, noise, mini remixes, rearrangement of the stereo field, and a pile of scratched CD-Rs! Cool.

Below is a long example of the sound of a scratched up CD:

Below is another mp3 example of what I mean. The source was an acoustic guitar that I recorded to microcassette way back in 1990. The original recording had lots of noise in it to begin with. The audio has gone through 11 rounds of CD Trauma (more on what that means later).

Audio mp3 demo of Suburban Thunder
CD scratch example

Like what you hear? Of course you do.
So, you're probably thinking that you'll just take a razor blade to your prized CDs and then bathe yourself in beautiful glitch bliss. Not so fast, cowboy (or girl)! Once again, I have sacrificed my time (and dozens of CD blanks) all in the name of science and I'm going to pass on my findings to you (so that you can better take advantage of "CD Trauma").

What you'll need:
1) CD-R blanks - lots of them
2) CD player
3) something to record to a CD (a computer drive is fine, but if you have a standalone CD recorder, even better!)
4) fine grain sandpaper (I've been having good luck with 220 grit - around $2 at Home Depot)
5) razor blade or "exacto knife" * optional * (WARNING: don't cut yourself! If you're under 18, proceed only under adult supervision!)
6) patience (this gets kind of tedious)
7) time - CD Trauma is a "real time" process and then some.

Other than the "razor blade" warning above, you're going to go through plenty of CD-Rs - which cost money (by "going through" I mean that you may render many of those CDs useless - as in "they have too many scratches to play anywhere" and are only good for being a drink coaster). Also, playing scratched up CDs is probably going to put a lot of extra stress on your CD player. It might damage and/or greatly shorten the life of your CD player. I have yet to break a CD player doing this, but you never know and I don't want any "hate mail" saying that I didn't warn you. So, PROCEED WITH CAUTION and DON'T FORGET that razors are sharp and they can cause bodily injury if you're not careful!

What you do:
Step 1: get some audio onto a CD-R - your own recording as we're not into copyright violations 'round here. A few minutes is fine since this is a "real time" process.

Step 1.5 will save you lots of time and heartache and is highly recommended: Make a copy of this CD, then set aside the original. You'll be scratching the "copy" disc and if you go too far and the scratched disc won't play (more below), then you have the "original" disc which you can copy from and start over again.

Step 2: scratch your CD lightly and in relatively straight lines moving away from the center of the disc. Oh, and make sure you're scratching the "dye side" (the under side) of the disc. Please refer to the large picture at the top of this page which shows a CD-R that is playable, but probably has a little too much "scratch density" to it. In addition to the sand paper, you can use the razor blade to scratch a few lines out from the center, but only a few (4 or less). This process is all about BALANCE. Too many scratches and the disc won't play. Too few and the CD player's error correction makes your CD sound like the original. So, start slowly and test by playing your disc. You can always add scratches, but taking them away is another issue (yes, there are CD repair kits, but I haven't used one for this process - it might work, though).

Step 3: Once you have a sufficiently "glitching" disc, you'll want to get that audio to a fresh CD (because we want to do this process over several times - if once is fun, then 11 times kicks ass!). So you take a digital out from your player to your CD recorder (if you have one). If not, record your glitching CD to your computer and then transfer that audio to a CD-R in your computer drive.

Step 4: Repeat from Step 1 I've found that after 4 or 5 times through this process and things really get interesting.

Here's what scratching your CDs is doing (at least this is my opinion). Scratching the disc causes the laser light to reflect differently than a non-damaged disc. This "corrupts" the data which causes the CD player's error correction to kick into "high gear" (there is no "high gear" in CD error correction but "high gear" sounds cool). OK, the CD player tries to interpolate that data that is either missing or that is confusing to the player. The laser will jump around to "less corrupted" on "non corrupted" data nearby to try to form a picture of what the audio should sound like. This results in "jump backs" and "jump forwards" where the player quickly goes to nearby parts of the audio and plays brief sections, sometimes looping almost endlessly, but slowly changing at the same time.

You can hear some CD Trauma in my recent podcast:

podcast icon "Difficult Listening Channel - show 94" My experiments continue. Now hear this - an unlikely combination of abused sounds that's sure to get you motion sick. Headphone listening recommended.

show release date 10-25-2006

Subscribe - xml or Download - mp3

CD Trauma Tips:

Start by lightly scratching the CD with the sandpaper making tiny scuffs and scratches. Remember that you can always add damage, but it's just about impossible to reverse it.

I very strongly recommend that you follow Step 1.5 (right) and copy your "master" CD-R and then apply "damage" to your copy. More than likely, you'll make plenty of coasters before you get the hang of things.

You may find that some CDs only need a little "trauma" to get them glitching while others take a bit more abuse to get them going. Experiment.

If your "scratched disc" doesn't work, try ejecting it and then re-inserting it. Sometimes players need a little "convincing" to get going. Remember that this will increase the wear and tear on your CD player!
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Michael Oster's Discography Here's a list of the CDs and CD-ROMs that I've made since 1997. This does not include releases by other artists that I've worked on. more