ATRAC Listening Test

What is ATRAC?

ATRAC stands for Adaptive TRansform Acoustic Coding. It's a lossy audio codec developed by Sony in the late 1980s and early 1990s so that CD-quality audio (or something perceptibly similar) can be stored onto a MiniDisc.

Why was ATRAC developed?

On a CD, 80 minutes of audio are encoded into 700 megabytes of data at 44.1kHz sampling rate and 16-bit resolution. Since a MiniDisc can only hold about one-fifth of the data, much of the audio has to be thrown away to allow a MiniDisc to have the same playing time. ATRAC attempts to throw away the audio that you cannot perceive. This is very similar to the way MP3 files work.

What bitrate does ATRAC use?

There are three main bitrates used for ATRAC:

ATRAC SP mode (292 kbps)
ATRAC3 LP2 mode (132 kpbs)
ATRAC3 LP4 mode (66 kpbs)

In 2004, Sony introduced Hi-MD MiniDiscs, which are capable of recording in lossless CD-quality PCM encoding.

Can you hear the difference?

Many people claim to be able to hear the difference between CD audio, SP mode, LP2 mode, and LP4 mode. Now, you get to see if you can hear the difference yourself. This website contains a randomized blind listening test between CD-quality PCM, SP, LP2, and LP4. Thirty-second samples of twelve different songs will be presented to you in CD quality, SP, LP2, and LP4. You'll listen to each sample and guess which codec has been used to encode it. At the end of the test, your guesses will be scored and you'll find out how good your perception is.

How were the audio samples made?

CD-quality lossless audio in FLAC format was transferred from a computer to an Onkyo FR-N9X Hi-MD MiniDisc deck using a TOSLINK SPDIF cable. All transfers were done at 44.1kHz with 16-bit resolution. The audio was recorded onto a Sony Neige MiniDisc in PCM, SP, LP2, and LP4 modes. The audio was then recorded from the Onkyo deck to the computer using a TOSLINK SPDIF cable, again at 44.1kHz 16-bit. All audio recorded from the Onkyo MiniDisc deck was encoded as lossless FLAC files, which you will be listening to during the test.

How should you listen?

Use your best headphones or speakers and turn up the volume. You should take the test in a quiet environment.