When visisonics kindly lent us their spherical microphone array, we wanted to capture some really interesting acoustic spaces. So, we loaded up the car and headed up the road to Emmanuel church.
In fact, Emmanuel has two rooms that acousticians might refer to as churches. The main church is a large open space seating 400 people, with a large balcony towards the rear. Then, the original church building, a typical turn of the century single nave church seating 100 people, stands just next door. Putting a trolley to good use, we were able to record in both rooms in one afternoon!
The visisonics array has 64 microphones spaced evenly around a sphere, and also records HD video from 5 cameras. Not wanting to miss an opportunity, we also brought along our 48 channel dual circular open array of omnidirectional microphones, together with a sound field microphone. In total we recorded impulse responses for 116 microphone channels, measuring 9 loudspeaker positions in each room.
So, what will we do with all the data? Well, it can support our spatial audio research in a number of ways. We can analyse the impulse responses to learn about the room geometry, predict the positions of the walls, and derive parameters for parametric reverb techniques. We could attempt to separate the source sound from the reverb it creates, to learn about making and transmitting recordings in large spaces. We could even combine the microphone recordings and the video to predict the room response at positions we didn’t measure! All of these things will help us make recordings that can give a listener a sense of being in the recorded room: we’ll take you to church!
The data will eventually be freely accessible. So, what will you do with it? Where should we record next time we load up the car? How many channels is too many?! Jot your thoughts in the comments below!
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