Task Error- Acquiring Sound from Multiple Sound Sources (not one sound card)

[cnassouri]

Hi there!
I am a grad student working an audio localization project.  My goal is to find the angle of the sound using three microphones.  Here is where I am stuck:

I bought 3 USB mics and plugged them into a hub.  I plugged the hub into my USB connector on my laptop.  Labview detects the mics, and when I try to use the "Acquire Sound" functions, I get a message about a task error.  Right now I am just trying to get this to work with 2 mics.

So then I tried to modify the ContinuousSound.vi and I am having troubles with task again.  I see that Sound Input Configure is probably the culprit, because it spits out a task and when I am in my main loop trying to acquire two sounds, it probably gets confused because my sources have different tasks.

I even tried taking the task output of one "configure sound" and putting it into the second sound's "read sound".  

My goal is to have it acquire all sounds at the same time...with no errors!!

Also, I am having great difficulty finding a sound card or device that can give me 3 channels of input (this thing needs to be portable and cant haul around expensive audio equipment and drag cords)...so suggestions there are welcome of course.

Posting my VI.  

Thank you in advance!! I really appreciate it.

Crystal Nassouri

Electrical Engineering Grad Student  

University of Southern California 

[Coq_Rouge]

Hi first of all. You have a serious problem. I guess your microphones work as 3 separate sound cards. And the input from them will not be synchronized in any way. What you need is 100% simultaneous sampling of all 3 microphones. A 3 input sound card with simultaneous sampling. I guess it is out there.

You have this one http://www.esi-audio.com/products/maya44/ and for USB http://www.esi-audio.com/products/maya44usb/ both has 4 inputs. I do not know if the input stream is simultaneous. Contact ESI-Audio support and ask them. Sorry for your bad microphone investment  

[cnassouri]

Thanks for you reply! 

I hunted all weekend for exactly that USB 4 in 4 out type device and did not find one. Thank you so much... I figured that 3 separate sound card devices was not going to work.  I will call ESI today and ask them if it is simultaneous and let you know.

Thanks again!  

[cnassouri]

Actually, I still need an answer for this.  

If I have three different sound cards (or sources) then they will not come in at the same time, but there is a starting timestamp that arrives with each.  I can adjust my timestamps so that they line up and use that for localization.  But thats another issue.

So, back to original question.... How do I acquire sound from multiple sound sources (not one sound card)?  🙂

[Coq_Rouge]

The time stamp is coming from the system clock which has a resolution around 20m seconds. Since your project is an audio localization project. I will guess this is not good enough. I have also a question. How often will you update localization data. I am askin because the sound system introduced in Labview 8.x is a piece of crap. It get confused if you try to update sound more often than 5 times pr second.

[cnassouri]

Okay I'm back.  

I went ahead and picked up a Maya44 USB!  I have a phono to 1/8" adapter so I can use normal analog mics.  I installed the driver off the ESI website...

I know this is getting out of the scope of the original topic, but when i plug in my mic, the light doesnt turn green at any of the ports on the Maya44, indicating that it is not detecting the mic.  Windows however recognizes this device and the driver seems to be installed correctly.

Thanks.. 🙂  

[cnassouri]

Actually I'd like to ammend my previous post...  Windows users who use the Maya44 USB should watch out because though Windows "recognizes" this device, its not always recognized as an *audio* device.  I had to uninstall and reinstall the driver about 3 or 4 times before it actually recognized it as an audio device. 

Just an FYI...

Also tomorrow I will be testing the device with 3 microphones and studying the degree of latency of this device.  I have a good feeling about this...thanks again for the product suggestion! 

[Coq_Rouge]

Happy to see you have made some progress. This is your thread so post again if you need some more help. Also notice that the MAYA44 usb only seams to support 44.1kHz, 48kHz samplerates. It is common now that soundcards do not support "all" samplerates, like before

Ps may I have your MAYA44 USB then you are done 

[cnassouri]

Hey! Update here:

Got some phono to 1/8" microphone adapters (Maya44 has phono line in inputs) and plugged in cheapo microphones.  All I got was noise, didnt seem to pick up the sound I was making.  After playing around with it, including plugging in a set of headphones into the line in (I got a waveform when I did that!), I realized that it probably needs a preamp since there isnt enough built in gain to acquire microphone input from a line in.  Is this correct?  If so, I am thinking about switching to the m audio fast track ultra which has 4 inputs and a built in preamp instead of buying a preamp. The lack of mobility sucks, but its going to have to do if its what it takes.

http://www.m-audio.com/products/en_us/FastTrackUltra.html

Is my thinking correct? Or am I missing something?  If so, do you want to buy my Maya44 😉