Rockbox Development > Feature Ideas

"White Noise" Sound feature!

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Reece:

--- Quote from: wodz on January 15, 2013, 01:27:45 PM ---Maybe I am missing something but from my limited signal processing knowledge it should be 'noise' in reverse phase to the ambient noise (which is not exactly white noise). I heard of systems doing online FFT and artificially generating anti-phase noise to do noise cancellation but this is much different to simply mixing with noise.

--- End quote ---

Can you re-phrase that? I don't quite understand what you are asking.
Sorry...

wodz:
My point is that noise cancellation is much more then simply mixing with white noise AFAIK.

Reece:
      There is no technology out there that digitally (truly) cancels out all sound. Accept by means of physical features such as specialty glass and such, but I am talking about digital cancellation. The white noise cancels out all low frequency sounds. And yes, it is that simple. Noise canceling headphones have one or more microphones, and electronic circuitry which uses the microphone signal to generate a random "antinoise" signal. When the antinoise signal is produced by the speaker in the headphone, destructive interference (the white noise AKA antinoise) cancels out the ambient noise as heard within the enclosed volume of the headphone.

So all we have to do, is to utilize the built in mic in most players, to generate the antinoise signal. There fore canceling out low frequency/ambient noises around you, enabling you to hear your music better.

EDIT: And of course you have to have decent speakers/headphones for it to work well.
         Its a great option to have...

saratoga:
If you want white noise, just convert all your audio files to 8 bit.

No need to add noise when you can just lower the bitrate on your files :D

[Saint]:
At least the thread is aptly named.

By my understanding, this method is not noise cancellation at all...wodz describes it best. Noise cancellation is actively adapting to the situation at hand, mixing in the required amount of anti-noise for the situation, rather than mixing a predefined amount of  white noise (which is different to anti-noise) with the audio. Otherwise known as active noise control. Passive noise control, by my understanding, uses only dampening/muffling of ambient sounds and does not attempt to cancel it by adding an anti-noise singal.


[Saint]

EDIT: Perhaps some of the many fine products listed here can banish the unwanted noise from your audio system before it is even created. ;)

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