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Thread: Noise Cancelling Program On iPhone

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    Default Noise Cancelling Program On iPhone
    I would like to see a program that uses the iPhones mic to detect ambient noise and cancel them out so that i could use normal headsets and have the iPhone as a built in noise canceler. It could run in the background of the ipod. Would anyone else like to see this?

  2. #2
    Sorry, not possible. The speaker is too far from the mic. The mic needs to be less than 0.5cm from the speaker to cancel frequencies up to 30kHz. At about 30cm, or 12 inches, noise cancelling could only be acheived for frequencies up to about 500Hz. Without even considering the processing power, the harmonics that can be filtered are physically dependent on the distance of the speaker to the mic.

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    agreed with ronanm

  4. #4
    Quote Originally Posted by RonanM View Post
    Sorry, not possible. The speaker is too far from the mic. The mic needs to be less than 0.5cm from the speaker to cancel frequencies up to 30kHz. At about 30cm, or 12 inches, noise cancelling could only be acheived for frequencies up to about 500Hz. Without even considering the processing power, the harmonics that can be filtered are physically dependent on the distance of the speaker to the mic.
    i feel like Ronan has gone to college
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    Ronan just owned this thread!
    Android user suffering from iPhone withdraw.

  6. #6
    Thanks guys, it was nuthin' really. I guess smart people "Mod their I-s"
    I wrote my first sound digitizer and compression algorythm in 1985, so I'm a bit long in tooth as far as this stuff goes. I'm not a professional, just do audio for fun.

    For cost effectiveness, I would suggest in-the-ear phones. Simply put, they are not bad at blocking outside noise, by just plugging up the gap! Add a decent micro speaker, and you're set.

    I use something like this in airplanes, index
    and they perform better than the bulky, expen$$$ive digital noise cancelling mics. Stands to reason, the same would hold for the iphone.

    I havn't tried the iphone specific ones like V-moda Duo, or Ultimet Ears Super.fi 4vi (yet). V-moda has (on paper) a better frequency response, but audiophiles seem to like ultimate ears more (then again, they also like analog, vinyl and tube amps)

    The best one is the one that sounds best to you, not the one that necessarily produces the most exact copy of the original sound.

    Oh, and rip your music at 192k-256k. I find 128k is OK for a car stereo, just doesn't cut it with the "3D" effect, or "imaging" when you play back on headphones.

    I'll spare you the neurophysiology of 3-dimensional sound perception (unless you want to know more).

  7. #7
    i would love to know about the neurophysiology of 3-dimensional sound perception.. and yes i did register, just to ask this... honestly i want to know! lol

  8. #8
    I typed up a long description, but the forum would not take it, so rather than type it out again, I'll refer you to "Neuroanatomy" by MJT Fitzgerald, 3rd edition pages 158-162, ISBN 0-7020-1994-1. Should be possible to get this or similar at any library.
    In summary, some spacial processing is done at the brainstem level. It is thought that some phase and tone processing is done there, and the resulting information forwarded to the cortex for additional interpretation.
    The olovary nuclei can probably use phase and volume to source a sound.
    The same sound arining at both ears will in one ear be louder, and be out of phase to a certain degree, depending on the frequency and direction.
    Front/rear processing relies more on the tone profile of recognized sounds changing according to position. The shape of the ear will amplify higher frequency sounds from the fropnt, but from the rear, these same sounds are dampened.
    If these effects are applied to a good pair of earphones, the sound can be made to seem like it is coming from any direction.
    So why have a whole bunch of speakers for surround sound, if it can be done with two? In a less well controlled environment, eg a room or movie theatre, it is not possible to make the phase and frequency shifts work well for all positions of the listening area. More speakers means that the sound can actially be sent from close to the desired direction, rather than relying on simulating the end users experience.
    A really good pair of headphones with spacializing software should give just as good, if not better result, except for the low base, which is sensed by the body, and not in the ears.

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    ^^^
    That's what I was going to say...

  10. #10
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    Utimate Ears are quality head phones. I own a pair but the connection at the end was loose because of me being stupid and careless. But the sound quality is very good.

  11. #11
    Quote Originally Posted by dalythu View Post
    I would like to see a program that uses the iPhones mic to detect ambient noise and cancel them out so that i could use normal headsets and have the iPhone as a built in noise canceler. It could run in the background of the ipod. Would anyone else like to see this?
    Let me introduce you to my app (soon on AppStore), I'm sure it can help you with the noise. It's not about noise cancelling by phase shifting but it is about hearing the music when loud noise is heard (or vice versa limiting when noise is heard)





    It's called AutoVolume (Automatic Music Volume Control for iPhone) and it will be SOON on AppStore.

    http://AutoVolumeApp.com

    video: AutoVolume - Automatic music Volume Control iPhone App - Automatically Adjust Volume by Noise - YouTube

    AutoVolume is a cool iPhone app that will constantly measure the outside noise level with the iPhone's built in microphone and then gracefully adjust the music volume depending on the noise outside and your personal settings.

    Use it while traveling on noisy transport that is making stops, walking on loud streets. It is also able to instantly lower the music volume when noise is heard (limiter). Making it useful in office or during any kind of activity that requires your sudden attention. More over it responds when you start talking.

    --------------------------------------------------------------------------------------
    More details: AutoVolume - Automatic music volume control for iPhone

    You can SIGN UP now and you will be NOTIFIED when AutoVolume is available on the AppStore! Click to sign up now: AutoVolume Available Notification

    Like me on facebook and I will work harder: AutoVolume for iPhone | Facebook

    Twitter: AutoVolume (@AutoVolume) on Twitter

  12. #12
    Thats not a bad idea. The headphone mic would likely hear similar noise level that the listener would. Even with in-ear buds, I still find myself reaching for the volume clicker in noisy places, e.g on the bus or plane. I think this would be a good app.

    Many automotive sound systems tie into the vehicle speed sensor, and adjust the audio level up when moving faster. You could add a "velocity" mode where the algorithm uses GPS derived speed as an alternative variable with which to adjust volume.

    It would be an interesting experiment to monitor the power of the noise in various frequency bands, and boost the volume only in the corresponding band - think "adjusting a graphic equalizer, but optimized for the noise environment". I'm not sure if it would sound any better than just adjusting the volume overall, but I would be very curious to find out. Imagine automatically turning the treble up for high pitch noise (e.g. on airplane), the bass for low pitch (e.g. the diesel engine on a bus) and the mid for speech and chatter noise.

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