Soundhound's Bit-Rate Sample Track

Soundhound, a member of the Outlaw Saloon, recently started a "listening challenge" thread in the Model 950 forum. The topic? A music sample that he had manipulated to include sections playing at 16-bit, 12-bit, and 8-bit. When does the track switch between bitrates? Ah, but that's the idea -- it's his little secret. The song used is Miles Davis's "So What" from the Kind of Blue CD (20-bit remastered version, Columbia/Legacy, catalog # CK 64935) and runs about nine minutes long. Soundhound offered to mail a few copies of a CD containing this "doctored" track to interested forum members so they could try to hear the difference, and he has sent out five copies and asked that those who get a copy also pass it along to anyone else interested in the "listening challenge." I've removed the rather large wav file from my site for the moment (it hadn't been downloaded in a couple weeks, so I figured I could reclaim the disc space), but it is currently being hosted at AudioEnvy, an excellent site for home theater fans interested in demo'ing some of the direct-to-consumer Internet-based product lines like SVS and Divas.

 soundhound_challenge.wav removed from site -- available here from AudioEnvy.

Here's Soundhound's original post in the thread, explaining how the track came to be:

Hey Guys and Gals:
Something you might be interested in...

A couple of years ago I got into a (heated) debate with a friend regarding the then new stereo 24 bit/48K audio DVDs coming onto the market. He swore that the sound of the 24 bit "wipes out" the cound of the same program on 16 bit CD. He swore that the difference was "enoumous" and that he could tell instantly which was playing.

I couldn't leave that hanging.

Having a lot of time on my hands, I took the title track from the audiophile re-release of "Kind of Blue" by Miles Davis and imported it into my digital audio workstation (a professional ProTools 24 bit system). Using professional mastering software, I made two additional versions of the track; one bounced to disc as 12 bits (the lower 4 bits set to 'zero') and one bounced to disc as 8 bits (the lower 8 bits set to 'zero'). Simultaneously, I applied noise shaped dither to both versions at their respective bit depths: there is _no_ information below the 12 or 8 bit level on those versions. (Noise shaped dither is less audible than straight dither, and linearizes the least significant bits better). I then took the original 16 bit version and the 12 and 8 bit versions and laid them on my workstation's screen, and sliced them into sections. I took the different bit depth sections at random and edited them into a continuous file at 16 bits so that it could be burned to CD, noting the time where the switching from 16 to 12 to 8 bits occured relative to the display on a CD player, then burned the result back onto CD.

Hey, if 24 bits 'wipes out' 16 bits, then hearing the difference between 16 bits and 12bits or _8 bits_ (!) ought to be like shooting fish in a barrel, right?

So I gave him the CD and he said.........(-:

Anyway, if anyone wants to have some fun, I'll make five of copies of this CD and pop them off in the mail to anyone interested, with the provision that they in turn send it along to anyone else interested, after listening and posting your impressions here. You can also feel free to rip a copy of the CD before passing it along.

Of course, I am not going to reveal right now the timings of the changes....but I will, in due time (-:

Any takers?

The track switches can be found here for anyone who is interested.

- gonk

[an error occurred while processing this directive] hits since 10/11/2002