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hello everyone….
i’m trying to record a sound using fmod and, i want to know the sound’s frequency that i’ve just record…

i’ve read the [b:zoqvcwdz]pitch detection[/b:zoqvcwdz] sample program but what want to do is more simple than this sample. pitch detection sample determine the pitch of the sound being recorded. my purpose is just to know the frequency of sound that being recorded..

so to summarize it

record sound –> measure frequency –> if (freq> 100Hz) {do something} else {do other thing}

any comment, help, or feedback would be appreciated

thx.. 😀

regards

alfa

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Did you read the article at all?

[quote:3oen40ac]
The noise/sound of someone blowing into the mic is made up of low-frequency sounds. We’ll use a low pass filter to reduce the high frequency sounds coming in on the mic; when the level of the filtered signal spikes we’ll know someone’s blowing into the mic.
[/quote:3oen40ac]

[quote:3oen40ac]
As mentioned in the overview, we’ll be using a low pass filter to diminish high frequencies sounds’ contribution to the level.
[/quote:3oen40ac]

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yes i have read the article

what i mean is

[quote:1k5w3xrw]The noise/sound of someone blowing into the mic is made up of low-frequency sounds.[/quote:1k5w3xrw]

how did he found that out???

or how is he sure that someone blowing into the mic is made up of low-frequency sounds??

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The frequency to pitch conversion code is in that example. Just don’t convert the frequency to a pitch value.

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Not sure. I’m not aware of a formal definiton of "blowing into a mic." My guess is that it’s just based on empirical data and the fact that it’s easy and cheap to check the results of a lowpass filtered sound. Your two graphics show a similar pattern, with the majority of the sound’s energy in lower frequencies.

As he mentions in the article, it’s hardly a perect technique. A more sophisticated approach might be to attempt some sort of cross correlation technique against a library of known blowing samples, or perhaps even looking for a linear decay in frequency vs amplitude like in your graphs. Then again, you’ll certainly have diminishing returns vs the simple lowpass approach, so it really depends how precise you need it to be.

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I was wondering if pitch detection works on the iPhone. Does everything in FMOD work with iPhone (understanding CPU usage limitations)

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Yes it would work the same way as on PC

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hello it’s me again,

first i want to say thanks for the reply, i’ve figured out the frequency..

also now i’ve figured out the amplitude and the decibels,

i got another question, how can i determine blowing sound, and capture only the blow sound???

what i mean by blow is like when you try to blows light candle for example, or like you blow when playing bubbles..

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That’s not necessarily a question with a simple answer. Have you done any research on the topic? Have you recorded samples of blowing sounds on your device microphone and looked for unique features (in time or frequency domain)? Those would all be good places to start.

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yes i have,

actually after i record several blow sound and using getspectrum() function from fmod, i got the frequency data and decibels. after i plot it, frequency in X axis and decibels in Y axis, i get this graph in freq domain, from blowing sound, here’s what i got:

[img:1ipavlf9]http://picasaweb.google.com/lh/photo/lfAZhE1tZRivk3UwJ1pUiw?feat=directlink[/img:1ipavlf9]
[img:1ipavlf9]http://picasaweb.google.com/lh/photo/zCaWWySBszzQxTCveWNmOg?feat=directlink[/img:1ipavlf9]

i’ve been trying to record blow sound several time, the spectral isn’t look identically but it’s look similar don’t you think??

but i don’t know the next step.. how to tell my system that this kind of input that i needed..

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[url:2hl2y4q3]http://www.mobileorchard.com/tutorial-detecting-when-a-user-blows-into-the-mic/[/url:2hl2y4q3]

Top result for a google search for "mic blow detect". Should be a good baseline, and very easy to do in FMOD w/ their DSPs or even with some extra code on top of your current FFT.

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wow thanks, nice….

i’ll go check it..

and i’ll be back again with my result or questions :)

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i’m curious why in this article

[url:zsze2wcm]http://www.mobileorchard.com/tutorial-detecting-when-a-user-blows-into-the-mic/#comment-4645[/url:zsze2wcm]

he’s using Low Pass Filter?

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