Manipulate sound going into a DAQ

[VeritasAequitas]

Do you mean hooking a frequency generator up to it? I don't have a tone generator or anything like that

[VeritasAequitas]

I connected my microphone circuit to labview program that outputs the sound through to sound card. The sound does get to the soundcard and you can hear what you say but its barely because mostly all you hear is white noise surrounding the sound. I have no idea how to get rid of this noise.

[VeritasAequitas]

I have my microphone connected to the Daq and i am using that example which takes the sound and outputs it to the sound card. Now the sound does reach the soundcard and the speaker but the sound is almost overcome by the noise coming out. How can i clear up the sound? is it the microphone itself or the circuitry associated with it? And how could i fix it.

[Corby_B]

Hello ajh305,

Thanks for your post! It seems to me that the noise is being induced before the DAQ system because the "white noise" and your signal are about the same. Since there is so much more white noise I would think that this is why you can barely hear a sound made by you. I.E. your voice. Since this is the case I feel like the noise is being amplified by your 100 gain amplifier circuit. One thing I would try first is to add DC filtering Capacitors between your DC power rail and ground. You are at 4.5 volts so maybe a cap value of 1 uF. I am no expert on this but I do know that if you DC power signal is not clean it can add considerable noise. I would give this a try and if you have any electronics books around it should have a section on this. 

You could also do an FFT in LabVIEW to see what frequencies are present. If there are any perhaps a low pass filter that only lets frequencies below 20K though. 

Let me know if this helps!

Cheers!

Corby_B

http://www.ni.com/support 

[VeritasAequitas]

Hello all. I have completely cleared up my sound and it comes through the computer nice and clear. Now the program that takes the sound and outputs it is way to complicated for me to understand. What is the bare minimum that i need to output this. After i figure this out what labview functions can manipulate the sound wave based on DB level to keep it at a consistent volume? To clear up my signal i actually took everything out but a 1uF cap and the 100 gain amplifier.

[Jason_D]

Hi ajh305,

This is easy to do with the Sound and Vibration toolkit.  If you do not have this as indicated by your previous posts.  You will probably have to do something like find the RMS or your signal compare it to the desired value and multiply by a scalar to get this new level.

[VeritasAequitas]

Here i have developed a program with the help from a few examples. I'll upload it and ask if you have any suggestions for improving it. I tried to measure the decibles out of the mic and placed that value in a y=mx+b equation to scale the gain to go from 1 when the decibles are 120 and to 6 when the decibles are 30. If you have a better way of doing this i would love to hear some suggestions. Thanks!