Listening test to tell the difference in audio quality between mp3 pla

2014-02-16 19:23:00

Dear Forum

I'm getting more and more interested in audio and audio quality, and I recently got access to new equipment (Tascam DR-60D field recorder) which sparked my interest and curiosity.

Now I'm trying to create a blind listening test to find out whether there is any difference in audio quality between my portable mp3 player and my laptop by recording into the Tascam. I realize I could just put on headphones and sit with my back to a person changing the mini jack between the mp3 player and laptop headphone output (first taking care to adjust audio levels) but I am trying to learn about recording and listening tests as well.

Here's the setup:
Playing back an mp3-file (the song "Two dancers II" by Wild Beasts, 237 kbps VBR) on either the mp3 player or the laptop. Recording from the headphone output from either the mp3 player or the laptop to the 3-4 stereo mini jack input in the Tascam DR-60D. I am recording stereo at 24bit/96kHz uncompressed WAVE. After this I would just try to listen repeatedly and randomly (with the help of a friend to make it blind) to each wave file directly on the Tascam to see if I could tell the difference.

Now here are my questions:

1) Is this a fair listening test that will show me the subjective difference in audio quality between the two sources (similar to the scenario where one just changes the headphone mini jack to either source repeatedly trying to identify the source)?

2) How do I adjust the audio levels correctly? Should I first listen with the actual headphones directly in the two sources to adjust the audio level in the player to the normal listening level I would be listening to?

3) Does it matter that I would have to adjust the laptop to the lower part of its volume range (about 10%) and the mp3 player to the upper part of its volume range (about 65%) to achieve about the same volume levels in the headphones because of question 2 above? For some reason I seem to think that the optimal audio quality from a player will exist in the 10%-90% volume range. Is this assumption true?

4) What gain settings should I use? Should I adjust the gain on the Tascam independently for the two sources to achieve a loudest signal of -6 dB for the maximum peak in the song? Trying this on my first try I think the audio was significantly louder in one of the recordings. Any suggestions for why this might be? When having set the audio levels in the players as explained in question 2 above wouldn't the same gain setting on the Tascam produce equal results because the output signal level from the sources would be the same?

Please let me know if you need more information about the setup or method.

As previously stated I am trying to learn about audio quality and listening tests, so any comments will be appreciated. Thank you.

I am looking forward to your feedback.