I
The Listening Challenge:
(right-click and choose "Save as" to download the files
below)
What is this
"Challenge"? It is has been a challenge to benefit you, the discriminating MP3
listener. The challenge has been a blind listening test to see if you can rank sound files from best to
worst, just by listening.
These samples have been encoded with three different encoders: Fraunhofer
FastEnc CODEC (bundled with MusicMatch Jukebox 6.1) Stereo CBR, Blade v0.927 (bundled with
dbPowerAMP DMC) Stereo CBR, and LAME 1.26 Eng 3.90 Alpha 8 MMX (bundled with CDEX 1.40 Beta 9)
Stereo CBR. The samples were encoded with bitrates ranging
from 160 kps to 224 kps and then decoded with dbPowerAMP back to .wav.
The original .wav file is also mixed in with the encoded/decoded samples. So what's the point?
The point is to demonstrate that a bitrate does not have to be ridiculously high
to sound good. I challenge you to prove that your ears can hear the
difference between an encode at 160 and 224. (This challenge has been around a
long time, as you can tell from the versions of the encoders.)
You can, of course, solve this
challenge with your eyes, so if you want to pretend you have great ears, you can
load these samples into a good .wav editor or other program that can do a bit of
spectral analysis. This used to be an in-your-face "put up or shut
up" challenge. But if you wish to cheat, it is not that
difficult. You can easily use Cool Edit Pro to see frequency cutoffs above
certain frequencies. But the whole point of this challenge is to use your
ears, not your eyes. Any moron can create a bloated MP3 at 256 kps using
any old encoder and then flood Usenet in a wasteful fashion, but a
discriminating MP3 advocate will use the bitrate necessary to get the best sound
at the lowest file size. It saves room on your storage media and room on
NNTP servers world wide. Download the following samples, unzip them, and
give your ears a workout:
sample01.zip
sample02.zip
sample03.zip
sample04.zip
sample05.zip
sample06.zip
sample07.zip
sample08.zip
sample09.zip
sample10.zip
key.zip (the answer key to the samples - password at the bottom of this
page)
The sample is the first 22 seconds
of "Only Time" from Enya's CD "A Day Without Rain".
These files are provided under the "fair use" provisions of
the copyright act. These very brief samples are of no commercial value and
are intended as research into the effectiveness of compressed audio encoders at
various bitrates. They will be deleted upon completion of the study.
Fair use as described at 17 U.S.C. Section 107. "Notwithstanding the provisions of section 106 and
106A, the fair use of a copyrighted work, including such use by reproduction in copies or phonorecords or by any other means specified by that section, for purposes such as criticism, comment, news reporting, teaching (including multiple copies for classroom use), scholarship, or research, is not an infringement of copyright.
In determining whether the use made of a work in any particular case is a fair use the factors to be
considered shall include -
(1) the purpose and character of the use, including whether such use is of a commercial nature
or is for or nonprofit educational purposes,
(2) the nature of the copyrighted work,
(3) the amount and substantiality of the portion used in relation to the copyrighted work as a whole, and
(4) the effect of the use upon the potential market for or value of the copyrighted work."
