My Experiment Setup: The Non-Technical Version

Introduction

This is the layout for my experiment. As you might remember, I am working on an acoustic localization project. By acoustic localization I mean the tracking of an object by the sound it makes. I’ve adapted the post from my own blog to make it friendly to even non-engineers.

The Goal

We aim to test a localization network using a pseudo-testbed. When I say testbed, I mean a system that tests an idea (in this case, my theory of localization). When I say pseudo-testbed, I mean that the testbed can’t actually localize the sound; it just collects data for me to work with. The idea is to see how noise in the room will affect my localization theory. The experiment consists of 2 parts: Record, and Process.

Part 1: Record

While this flow chart might look a little scary, it’s easy to understand. The orange dots represent microphones. I want a setup with 16 microphones arranged in 4 clusters, with 4 microphones per cluster. Each microphone will have its own channel of audio on a sound card. Most people know 2-channel audio as stereo:

I’ll need 16 channels of audio to record sound from my 16 microphones. The reason why I can’t do it with fewer channels is the same reason why you can’t fit 7 sodas into a six-pack—it simply won’t fit. Each microphone needs its own channel in the same way each bottle in the six-pack needs its own slot.

We connect our 16 microphones to 16 channels on a sound card, like the one below:

I will set up the sound card to output a computer file for every cluster. The file will have 4 channels, which will correspond to the individual members of the cluster.

Part 2: Process

Though this flowchart might look even scarier than its sibling, it’s very simple to explain. I open a program in MATLAB, which will read all my 4 files, and perform all the calculations required to get the location of the source. You might say that this process is similar to a high school physics lab, where you copy down all the data in the lab, and then figure out if your experiment worked (or didn’t work) the night before the lab is due . . . uh, I mean, after you collect the data. Hopefully I won’t get anything mixed up.

Technical Layout

I will be recording in the Smart Spaces Lab on the 5th floor of Calit2. The space available for testing is 90″ wide, 173″ deep, and 120″ in height. It’s a “glass house”- meaning that there are no actual walls, just tape marks on the floor. This will help us as we will not have to worry as much about echoes created when the sound bounces off real walls.

I will place microphones at the midpoints of the rectangle bounding the room for my first configuration. The overhead view should look like the following:

Each of the blocks represents a speaker stand outfitted to carry 4 microphones in a cross pattern.

I’ll need to record about 5 sets of data to get a good idea of how my method is working. I’m also interested in trying out other microphone setups, to see how they handle the noise.

Conclusion

This method isn’t as exciting as a real-time test bed, but analytically it’s a better setup, because it allows me to reprocess the same data in the same conditions multiple times, ensuring consistency. Please, if you have any questions, comment, or email me at vishal@ucsd.edu. See ya!