ambient noise cancelling project

[madokaaukawa]

I am going to design a project which will cancel the ambient noise. the device will capture the speaker's voice but eliminate all other noises from ambient such as high way, construction field, in airplane, etc..

I did some researches, the two microphones seems right direction. the first mic picks up speaker's voice, and second mic picks up noise. This two signals are mixed. Then if we do 180degree phase shift of noise signal, and add to the original signal, it will cancel out the noise theoretically.
However, I still confused, the first mic even can pick up noise, How can we cancel out the noise from first mic?

I really need some other opinions please!~

Thanks in advance

 

[FvM]

The purpose of your design isn't fully clear, I understand that you are mainly targeting to noise cancellation in sound
reproduction or recording. There's however a wider topic of active noise cancellation, that's at least related to
the basic problems you'll face with your project. For a brief overview see https://en.wikipedia.org/wiki/Active_noise_cancellation

 

[madokaaukawa]

basicly, we are using two mics. the first one mic will be placed as close as possible to the human mouth, which is for voice signal picking up(there will be some background noise mixed with voice for sure). the second mic is using for picking up the background noise. and then we can 180 shift of noise signal and add it to the voice signal to cancel it out.

above is just theoretically speaking. what i might need is some experts can give some recommendations. such as what dsp chip might be use in this project. or something i might not concern yet.

Thank you for all the replies

 

[FvM]

it will cancel out the noise theoretically

Theoretically, it will cancel only low frequency noise and high frequency noise from sources at rignt angle to the microphone axis.
It will also add a comb filter characteristic to the reproduction of the speaker. In practice, a microphone with a strong directional
characteristic or a noise compensating command microphone may achieve the intended purpose with less effort.

 

[libopku]

basicly, we are using two mics. the first one mic will be placed as close as possible to the human mouth, which is for voice signal picking up(there will be some background noise mixed with voice for sure). the second mic is using for picking up the background noise. and then we can 180 shift of noise signal and add it to the voice signal to cancel it out.

above is just theoretically speaking. what i might need is some experts can give some recommendations. such as what dsp chip might be use in this project. or something i might not concern yet.

Thank you for all the replies

I'm going to do a similar project - noise reduction recording system. Microphone array is under my consideration. Cause I'm new, there is a lot of questions such as CODECs, DSP or ARM, number of microphone, ectl. Disscussion will be welcomed all the time.

 

[madokaaukawa]

microphone array seems too complicated for my project. any other suggestions?
I would like to discuss all the time.

thx in advance