Audio Primer: Why Pink Noise is the Best Test Signal

Pink Noise

Few audiophiles share my passion for listening to test signals when evaluating equipment. That’s quite understandable.

But all would agree – from JA on down – that test signals are vital in measuring equipment and rooms. When measuring, the most common test signal in use is “pink noise.” But why?

Common answers include:

  • It contains all frequency components
  • It’s easy to use/generate
  • It contains equal power per octave, and humans “hear” power; and
  • It is natural

All of these are, of course, correct. But there’s a reason far closer to the audiophiles’ world: the pink noise spectral signature closely resembles that of music. It’s just that simple.

"Fly Away"

Not convinced? Compare the pink spectrum above to that of this Corinne May song that I chose at random. Except for the bottom few octaves, they share similar 10dB-per-decade falling slopes. This is not a coincidence.

The relatively weak bottom end (compared to pink noise) of this song is typical. Many recordings do not match the pink spectra down low. I believe this is a combination of music lacking sustained bass, EQ choices when mastering, and some loss of resolution of the FFT. But I don’t know for sure.

Lest you lose all hope for bass on CD’s and digital analysis thereof, check out Cowboy Junkies’ “Helpless” and Sting’s “Fields of Gold” (at bottom). These tracks are two of my bass references. And finally, we come to Max Richter’s “Blue Notebooks.” I know of no cut in my library with more bass extension -it’s nearly flat to 15hz!

You’ll get to hear a bit of pink noise at our upcoming room correction events.





"Fields of Gold"


"Blue Notebooks"



Saturday, February 25th, 2012 Audiophile, Bob, Technical