Last Thursday evening a group of our Year 1 Physicists heard a lecture by Dr Christopher Hicks from the University of Cambridge Department of Engineering at the Cavendish Laboratories.
Dr Hicks led the students through the mathematics of digital signal processing, showing how the waveforms can be averaged and weighted to then allowed the removal of background noise. This included using weighted moving averages and Fourier transformations to ensure that the broadcast speech was clear without any “noise” int he background.
He showed the internal working of the CEDAR DNS2, made by his company, which has been used in BBC outdoor broadcasts and Downton Abbey! This device won a Hollywood nomination for the impact it has had on film production. He discussed the ability of these devices to pick out speech which is being attempted to be made difficult to “bug” by loud TV noise at the same time, and explained that it is possible to filter our the speech as human speech has a very distinctive rate of change. It turns out the best way to hide your conversation is to run the bath, the flowing water has a very close rate of change pattern to the human voice!