Pink noise beat analysis -part2

 

windowing effect in the spectrum

peak detection method

1. method for AM sin wave
2. http://www.mathworks.com/products/demos/shipping/dspblks/dspenvdet.html#7
3. but for a drum beat, it fails, because the carrier wave is not a narrow band signal
4. need to use the neighborhood method, details here http://billauer.co.il/peakdet.html
5. noise in the signal can also effect the neighborhood method, so may need to to some threshold.
6. peak can be sharp or flat, so

Pink noise beat analysis -part1

pink noise [see wiki] is a very interesting phenomena where the frequency spectrum has a 1/f curve.

but many musical instrument’s harmonics often show this 1/f like curve as well, a interesting fact is, if the frequency spectrum curve is smooth (no leakages [see wiki] or holes ), then they don’t sounds like noise any more. otherwise they sounds more noisy.

blow is a sample pink beat I found from this link http://www.brusi.com/downloads.shtml, a download  link is provided below, you can try it first and then read on.

in matlab, the periodogram analysis shows the PSD like this,

and the time domain waveform as below

to compare it with another base generated by Maxim Vedenev

from http://dj-toolbox.9f.com/

and PSD

personally, I would say the pink beat is more rich with dynamics and sounds more attractive,and the drum beat is more pure and more leaky in the spectrum, but that’s not end of story.

I will post a second blog which explain the windowing effect on PSD and spectral smoothing. thanks for reading.