Friday, June 29, 2007

AM Cross Talk example

The human ear is very tolerant to noise. It can detect sounds from 20Hz to about 20,000 Hz. It's highest sensitivity is between 500 Hz and 5000 Hz. It has mechanisms for coping with sounds that are too loud, too soft, and even for noise filtration. Your brain, in it's infinite wison tries to hear signal instead of noise, and its far more effective than any software.

Here's a nice example: DivShare File - AM_Clip.wav
...and again with the volume adjusted: DivShare File - AM_clip2.wav
I cranked the volume at the end of clip 2 as the music fades out so you can hear the other station bleeding in. It's almost inaudible otherwise. I only heard it with headphones on initially. Our ears filter out the noise otherwise. I glean two things from this lesson:
1. I have very mixed feelings in the debate about 10Khz AM bandwidth Vs. 6 Khz... knowing how much noise is there already I think reducing the quality is probably a bad idea.
2. I also have very mixed feelings about the future of AM radio in terms of the audio quality I've come to expect from other media.

1 comment:

  1. Anonymous3:21 PM

    i run my recievers through hardware and software compressors. they help bring lots of signals "out of the mud. it's a bit hard on the ears though.