I have a confession to make… I don’t use iTunes. In fact, I don’t even LIKE iTunes. I use (horror upon horrors) MSN Music. *Dave will now run so that he can keep his geek card*. In fact, the reason I LIKE MSN is a little bit geeky. The long and short of it is MSN encodes in 160 kbs WMA while Apple opts for 128 kbs AAC. Why is this important? Well, higher bit rates equal higher quality music. 128 kbs is a good enough for most people. I’m NOT most people. I use these files to learn and transcribe music. How does the bit rate affect this? Glad you asked.
To do the lossy music compression, the encoders usually ‘discard’ sounds that are outside of most people’s hearing range. These frequencies are usually above 15-18k on the spectrum of sound. When a musical instrument is played, there are a lot of overtones that go up beyond this spectrum and interact and change the sound BACK BELOW THE THRESHOLD. Based upon some principals that I have no understanding about, the human mind can ‘fill-in’ the higher level overtones, which is great because it allows for smaller files to sound almost like the original recording. Again, most people cannot tell the difference.
Ok, so how does this all come back to MSN Music and transcribing? When transcribing music, one of the techniques is to slow the music down. Thanks to some great algorithms, a computer can slow the sound down without altering the pitch of the music. BUT, when slowing the sound down the overtones become VERY, VERY important. A lower bit-rate recording will turn to mush when it is slowed down. Also the ‘attack’ or definition of a note is in those upper level frequencies. When they are gone, it is much harder to ‘pick out’ notes.
The last thing is that my transcribing program Transcribe! supports playing back DRM’ed WMA files. It doesn’t support DRM’ed AAC files.