Tag Archives: microphones

Mics, and cameras and touch tanks, oh my!

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In the last couple of weeks Katie and I have been testing some options for capturing better quality visitor conversation for the camera system using external mics.

As Katie mentioned last month, each camera’s built-in microphones are proving to be a little unfruitful in capturing good quality audio for the eventual voice recognition system in “hot-spot” areas such as the touch tanks and front desk. As a result, we purchased some pre-amplified omni-directional microphones and set about testing their placement and audio quality in these areas. This has been no easy process, as the temporary wiring we put in place to hook the mics to the cameras is  not as aesthetically pleasing in a public setting as one might hope, and we discovered that the fake touch tank rocks are duct-tape’s arch enemy. Plus the mics have been put through their paces through various visitor kicks, bumps and water splashes.

As well as the issue of keeping the mics in place, testing has also meant a steep learning curve about mic level adjustment. When we initially wired them up, I adjusted each mic (via a mixer) one by one to reduce “crackly” noises and distortion during loud conversations. However, I later realized the adjustment overlooked necessary camera audio setup changes, and gain adjustments, affecting just how close a visitor has to get to one of the mics to actually hear them, particularly over the constant noise of running water around tanks.

So today I am embarking on a technical adventure. Wearing wireless headphones and brandishing a flathead screwdriver, I am going to reset all the relevant cameras’ audio settings to a zero gain, adjust the mic levels for mic balance (there are multiple mics per camera) rather than crackly noises, and adjust the gain until the sample audio I pull from the camera system comes out cleaner. I’m not expecting to output audio with the clarity of a seastar squeak, but I will attempt to get output that allows us to capture focal areas of clear conversation, even with the quietest of visitors. Avast me hearties, I be a sound buccaneer!

Can you hear me now?

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That’s the question we’re facing next: what kind of audio systems we need to collect visitor conversations. The mics included on the AXIS cameras that we’re using are built-in to them and just not sensitive enough. Not entirely surprising, given that they’re normally used for video surveillance only (it’s illegal to record audio in security situations), but it does leave us to our own devices to figure something else out. Again.

Of course, we have the same issues as before: limited external power, location – has to be near enough to plug in to a camera to be incorporated into the system, plus now we need at least some of them to be waterproof, which isn’t a common feature of microphones (the cameras are protected by their domes and general housing). We also have to think about directionality; if we come up with something that’s too sensitive, we may have bleed over across several mics, which our software won’t be able to separate. If they’re not sensitive enough if in enough directions, though, we’ll either need a ton of mics (I mean, like 3-4 per camera) or we’ll have a very limited conversation capture area at each exhibit. And any good museum folk know that people don’t stand in one spot and talk, generally!

So we have a couple options that we’re starting with. One is a really messy cheap mic with a lot of wires exposed, which may present an aesthetic issue at the very least, and the other are more expensive models that may or may not be waterproof and more effective. We’re working with collaborators from The Exploratorium on this, but they’ve generally up to now only used audio recording in areas they tucked back from the noisiest parts of the exhibit floor and soundproofed quite a bit besides. They’re looking to expand as they move to their new building in the spring, however, so hopefully by putting our heads together and, as always, testing things boots on the ground, we’ll have some better ideas soon. Especially since we’ve stumped all the more traditional audio specialists we’ve put this problem to so far.