How to pass a audio signal through a filter

Question

Gokul 2013-2-18

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评论： Sai Manas D C 2020-7-1

How to pass a audio signal through a filter ? It should work based on spectral energy i.e if its between 0-4 kHz it falls on speech band and If it falls between 4 kHz-8 kHz then it comes under noise band.Now the VOS(voice operated switch) should be activated if the signal is in speech band and it should be deactivated when it is in noise band. Can some one help me on this problem.

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Jan 2013-2-18

Please explain, what you have tried so far and which problems occurred. Suggesting improvements is much easier than solving your problem completely from scratch.

Gokul 2013-2-18

I am a beginner and i need some ideas to start up with.So can u please help on how to get start with it.

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Answer 1

Carlos 2013-2-18

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The first step is to design a filter to obtain the A and B vector coefficients.Then use the Butter function, for instance to obtain your signal(type Butter in your Matlab command window and you will find many other type of filters). Once you have obtained the B and A vector coefficients you can filter your signal using the function filter.

y=filter(x,A,B) x(is your input signal) and y your filtered signal.

Once you have filtered the signal you can calculate the spectral energy before and after filtering to find out if the filter has removed a significant part of your signal.

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Odrisso 2014-11-14

Hi Carlos. I have aquestion on your code. Why you choose 6 in the line: [b,a]=butter(6,wn);

Please let me know.

Sai Manas D C 2020-7-1

6 is the order of filter, it can be any real integer. Greater the order of filter it's response approaches nearer to ideal characteristics

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Answer 2

Carlos 2013-2-18

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This is fine at the moment. Now filter with from 0 to 4000Hz to make sure the results are different(I mean if you filter from 4000 to 8000Hz and the signal after filtering is the same, then filter in the 0 to 4000Hz band to make sure the signal changes in this case).

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Darsana P M 2017-3-16

If i want to divide the given audio signals into different frequencies ie 20-30 Hz, 30-40Hz and so on. What should i do?

Walter Roberson 2017-3-16

You could construct a collection of band-pass filters that you pass the same data through.

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Answer 3

dev sanghvi 2016-5-24

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you can check my video.

https://youtu.be/ZPNOgLwfjNc

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Answer 4

Sanjay Gupta 2017-3-2

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what is the significance of "wn" in the code?

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Walter Roberson 2017-3-2

wn is the cutoff frequency, specified as a value between 0 and 1 where 1 is the Nyquist frequency. This proportion of nyquist frequency is commonly used in filter specification, because it makes the filter calculations themselves independent of frequency.

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Answer 5

Zahraa Almousawi 2017-10-18

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if i have impulse response and i convoluted it with a sound and the sound become so noisy how can i filter it after the convolution function? i really need a help!