A friend of mine recently sent me a recording of a live solo violin performance, and asked me why it didn’t sound very good. The problem, he stated, was that the sound was very flat and sounded compressed, not like previous recordings in the same hall with the same recording equipment.
I was excited, not only to help a brother out, but because I actually learned about ways to measure this particular problem in one of the classes I took at PSU… finally, tuition is paying off… sort of.
I knew, that I would need to use a frequency or spectrum analyzer to see visually, what we could hear aurally. The program I used is a free download called Spectro. And can be used as a plug-in within your Digital Audio Workstation of choice… even garageband.
Each Example sample is also pictured with the corresponding spectrum analysis.
Example #1 (compressed):
- Bit Rate – 192 kbps
- Sample Rate – 32.000kHz
Example #2 (non-compressed… er, technically, less-compressed):
- Bit Rate – 256 kbps
- Sample Rate – 44.100 kHz
You’ll see in each of the spectral analyses that the partials reached are very representative of the sound. The first example barely reaches 3,900 Hz, while the second example reaches as high as 22,000 Hz.
I also think that you’ll be able to hear the difference in sound as you listen. Example #1 sounds very flat, and almost as if it’s low fidelity. While the second example sounds more “live in the room”, and much richer.
My friend and I are agreed that the loss of fidelity most likely occurred during the initial bounce when the transfer was made from the original disc to mp3.
You can see from this comparison picture that the lower the bitrate, the less dynamic of a range that will remain in the acoustic envelope of sound… basically you’re losing a good portion of the overtones, which is definitely part of the music (even though you may not even notice it).
Ideally, you would want a Lossless rip, or for most types of music, 320 kbps… minimum 256 kbps. Anything less and you start losing a lot of sounds, or at least the sounds that help make up the music you’re supposed to be listening to.
So now, with this information, you can see why it’s important to use greater bit rates when ripping your new Mastodon CD, or downloading a copy of the soundtrack from Beauty and the Beast from your favorite online music store.