Surround Microphone

I was watching Glee and a thought occurred to me. It was the final episode of Season 1 at the regional singing competition. Rachel and Finn walked down the aisles through the audience singing their parts. Then, I thought to myself what it would have been like to be seated in the audience and listening to them sing. That was when it occurred to me.

It would be cool if they had wireless microphones on that were location aware and that information was integrated into the sound system of the room. So, as Rachel walked down the left aisle onto the stage, the surround sound system in the auditorium would amplify their voices, but it would sound to everyone in the audience that the source of the voice was from exactly where Rachel was standing.

This should not be something too difficult to do. Let’s explore this idea a bit.

Most of the hardware complexity would be in the speakers and the software complexity would lie in the sound system. The trick would be to transmit a hidden signal within the actual audio transmission. This signal would be picked up by the microphone on the singer. Using some algorithm magic, we can estimate the position of the microphone in the room in relation to the position of the speakers. This can then be used to calibrate the voice stream received by the system to do its surround sound magic.

This has the advantage of being a cheap option. We can do this with present day equipment. This is the passive surround mic.

The hidden signal can either be embedded in the very low frequency or very high frequency range. Knowing how amplifiers work, it would be better to stick things in the lower frequency range. Then, to prevent picking up noise, we can borrow some ideas from infra-red transmitters – to not only transmit a signal but to transmit a digital signal over this low frequency. This allows checksumming and error correction to be done.

The resolution of such a system may not be too great, but it should be scores better than the overall ambient amplification we get today. The response time of the system may also not be that great. However, it will definitely be good enough to deal with most concert situations where people do not move faster than a speeding bullet.

To improve this all, we move onto the active surround mic. We will just need to equip the microphone with a wireless transceiver and mount a bunch of base stations on the speakers. The mic can then triangulate its own position relative to each base station using the strength of the wireless signal and also transmit its voice data to the nearest base stations over the same frequency.

C’est bonne idée, n’est pas?

PS: I’m not sure if such things are already in the market, I am not an audiophile – but they certainly should be!

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Published by

Shawn Tan

Chip Doctor, Chartered Engineer, Entrepreneur, Law Graduate.

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