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Author Topic: Pink Noise without Distortions?  (Read 3886 times)

SoundBurger

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Pink Noise without Distortions?
« on: March 21, 2011, 06:46:12 am »

To Admin - no idea if my real name is showing so please dont just summarily delete this post if its not.  Im new here.  Thanks.

Question for the sound experts.  Having a difficult time with this concept of Pink Noise.  I am in need of a solid "white noise-esque" sound to help with sleep, and im not sure what other forum to ask this on.

Is there a way to generate a consistent pink noise without *noticeable* distortion?  I have downloaded app after app on the iphone that play "pink noise" and without exception, they all seem to loop every 10 seconds, and they all have some sort of distortion that creeps up.  Almost always, its 8 seconds of perfection and 1 second of a "thud" ... or a "bleep" ... or a "swirl" ... or something.  Even if I could just crop out that one second and make it a 9 second loop, I would be in *heaven* ...

I contacted the creators of the app and they said with "random number generated sounds" its nearly impossible to generate a perfectly smooth pink noise. 

Please keep in mind I am not talking about distortions that can be seen on a graph or with instruments.  Im referring to laying in bed with one ear in the pillow and one up in the air, and hearing it with my own ears.  Usually *extremely* subtle but it ends up being like irritating dripping water as you wait 9 seconds for it to happen again ... and again ...

Im not even sure what my question here is, but what's your take on this?   

Thanks
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boggy

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Re: Pink Noise without Distortions?
« Reply #1 on: March 21, 2011, 07:59:33 am »

To Admin - no idea if my real name is showing so please dont just summarily delete this post if its not.  Im new here.  Thanks.
I'm not an admin but I see your real name clarly and perfectly ;)
Question for the sound experts.  Having a difficult time with this concept of Pink Noise.  I am in need of a solid "white noise-esque" sound to help with sleep, and im not sure what other forum to ask this on.

Is there a way to generate a consistent pink noise without *noticeable* distortion?  I have downloaded app after app on the iphone that play "pink noise" and without exception, they all seem to loop every 10 seconds, and they all have some sort of distortion that creeps up.
They generate only 10 seconds of pink noise at beginning, not continuously.
  Almost always, its 8 seconds of perfection and 1 second of a "thud" ... or a "bleep" ... or a "swirl" ... or something.  Even if I could just crop out that one second and make it a 9 second loop, I would be in *heaven* ...

They can scale random numbers if multiply it with number smaller than 1 (0.1, 0.02, or whatever)... then they will have more quiet noise (smaller relative RMS) without possibility to clip...

I don't know if I help anything :(

Regards
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bblackwood

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Re: Pink Noise without Distortions?
« Reply #2 on: March 21, 2011, 08:00:17 am »

What sort of DAW are you using? Many include their own noise generators...

This may also be a question better asked of our tech buds in Bruno and Dave's forum: http://repforums.prosoundweb.com/index.php/board,24.0.html
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Brad Blackwood
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Tim Boyce

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Re: Pink Noise without Distortions?
« Reply #3 on: March 21, 2011, 04:08:59 pm »

Spectrafoo will do very high resolution noise generation.

Use the option to lock the signal gen to the hardware clock. Makes much finer results.


capture a big file (10 min / 20 min / 40 min .. whatever). .

and use the 'snap to zero crossing' option in the Daw. That should give you a seemless loop.


if you're using a random number generator, try making it a mono file, it'll be unlikely that each stereo side will have identical zero-crossings.

ggidluck

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Re: Pink Noise without Distortions?
« Reply #4 on: March 21, 2011, 05:20:06 pm »

Have you tried Studio Six Digital's Audio Tools? Their RTA is pretty good. I suspect that the pink noise generator might be as well.

http://www.studiosixdigital.com/generator.html
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Bruno Putzeys

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Re: Pink Noise without Distortions?
« Reply #5 on: March 22, 2011, 09:26:38 am »

What you call distortions are actually two different matters. The first is that noise, ideally, is random. In randomness, anything is possible. Just like the ideal random ASCII generator will at some point deliver the entire Gettysburg Address, punctuation and all, a noise source will appear to produce bursts of regularity. If not, it wouldn't be random (http://en.wikipedia.org/wiki/Infinite_monkey_theorem). To make matters worse, our brains are exquisitely attuned to detecting such snippets and attaching significance to them. Amidst acoustical noise we hear burps, bangs, screeches and if you're very suggestible, voices (http://en.wikipedia.org/wiki/Electronic_voice_phenomena).
It's actually remarkably difficult to rig a random number generator such that these things don't happen. After all, what you're asking is all the randomness minus those randomly occurring bursts of apparent nonrandomness.
Secondly, as was already pointed out, they may be using a short snippet of noise that is being looped. This severely compounds the first problem because by repetition *any* part of the signal becomes recognizable and you hear it repeat. So if you plan to make your own "noise track", make sure it is very long.
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