PINK NOISE VS WHITE NOISE
Hi everybody I'm Dennis Foley from Acoustic Fields and today I want to talk about the
difference between pink noise and white noise because it's driving me crazy!
No, not really but I get a lot of inquiries, almost weekly, about these two terms and people
are really getting them confused and twisting around what they actually mean and more importantly
what we, as engineers, use them for.
So let's talk a little bit about it.
Pink vs White noise.
Pink Noise is the noise that you use to EQ your equipment.
We've all heard, well you run pink noise through your equipment and you do your measurements
and stuff like that especially with EQ.
Pink noise is very, very, very important.
That's the noise that we use for our equipment.
So, some people get that right, some people think white noise is the way to go and I think
here is where the confusion lies and if we get some definitions and a little bit of science
behind it I think that it will be a lot clearer for all of us.
Pink noise is the energy in every octave.
Okay?
Let me repeat that, pink noise is the energy in every octave.
White noise is the energy in every frequency.
That's the major difference between the two noises if you will.
We perceive sound in octaves, so we perceive sound in pink noise and people will say well
pink noise is tailor to the frequency response to our ears.
Well not really true.
Pink noise is the energy in every octave, we perceive sound in octave bands and the
physical structure of our ear, if you look at it closely, is designed to work with octaves.
The octave is how we hear sound.
Our ears are constructed in such a way that it's octave friendly so we hear sound in terms
of octaves.
Inside that octave is pitch.
You hear singers say "Oh he has good pitch" or "She has good pitch" well that pitch is
found inside the octave range of our hearing.
If a high note jumps off an octave and a low note jumps off an octave, it's the same number
of keys on a piano or the same number of frets on a guitar.
The notes are the same.
Sound producing activity or the notes, to our ears are a few bands.
Maybe 5 or 6 different bands of frequencies but the number of frequencies is many.
Okay let's illustrate this point through example and I think we're getting to the real core
of the issue here and through this illustration we will really get a hang of the difference
between pink noise and white noise.
From 400 cycles to 500 cycles that's a 100 Hz difference, that's 1 octave.
From 5k or 5,000 cycles to 10,000 cycles, that's 5,000 Hz but it's still 1 octave.
This is the key, right here.
Look at this ratio.
Each one of these frequencies is exponentially more in mathematical number than those, so
we have more frequencies.
The relationship is the same, the octave relationship is the same but look at the huge mathematical
difference.
So white noise has more energy from 5K to 10K than 400 to 500.
So there's more energy because there's more frequencies.
So for further clarification, we know that pink noise distributes energy the way we hear
in octave bands.
Pink noise, the energy is the same from 400 to 500 as it is from 5K to 10K.
Pink noise is the equal energy per octave.
Where pink noise is all about pressure and energy in each octave, white noise is all
about the individual frequencies in each octave.
So you can see hopefully the difference here.
I am really hopeful that this will clarify some of the things that I've been hearing
and some of the questions I've been getting.
Thank you!