Adventures in the Smart Spaces Lab.

Introduction

Hello all. It’s been awhile since I’ve done any documentation, so I will go ahead and start by talking about the actual setup in the Smart Spaces Lab here at Calit2. I’ll post the results I’ve been getting in another post.

The Technology

First, I’ll go into detail about the sound equipment I am using.

I’m using production-quality digital microphones for my project. Here’s a photo of one:

I’m using 16 of them to make 4 clusters of 4 microphones. Here’s a shot of them.

The microphones will connect to a sound card, shown below. (It’s the black box.)

The three steel boxes below it are called pre-amplifiers. Their job is to clean the signal from the microphones and send it to the sound card. The sound card then sends the signal to a computer, shown here:

For those of you who are engineering-inclined, here’s a schematic showing all the connections.

Building It

It’s time to roll up our sleeves and have at it. First order of business is the extension cords. The microphone cable is about 5 feet long, but we’ll need a lot more wire than that for our experiment. But to avoid a tangled and potentially damaging mess, some preparation is required. That means turning this…

…into this.

You might notice that I have color coded and labeled every connector. With 16 connections, this is essential, for organization. We will be mounting these clusters using a speaker stand:

You can see that the stand has a strange-looking piece of aluminum on it. This piece is part of something called the Industrial Erector Set.

The industrial erector set is just that–a set for building things.

We’ll be building clusters with this set.

Here’s a picture of the final product, waiting to be connected to our sound card.

I have put foam caps over the microphones, to make sure they fit snugly and that they are insulated from any vibrations in the aluminum.

However, I found that the spacing in these clusters was too small, and I couldn’t measure the time delay, due to a resolution effect, which I will explain in another post. I rebuilt the cluster to have a much wider spacing.

Currently, I’m running tests on the effectiveness of this new cluster at forming vectors towards a source. My source of sound is a PC speaker connected to my laptop.

From the desktop computer, I remotely play a music file on the laptop, and record the sounds the microphones pick up using a program called Adobe Audition. Here’s what a recording looks like

And that’s what I’m up to for now. See you later!