Sousaphone: Old School Funky Family at Greenbelt

 

Old School Funky Family from France were a complete surprise to me. I was wandering past the main stage; they pulled me in and got me moving. I could hear the bass line and then noticed that they didn't have a bass guitar. It turns out that the bass lines were being played by a sousaphone. I don't know much about brass instruments but I think that they are pipes with two open ends that produce a stationary wave with an antinode at each end and a node in the middle for the fundamental frequency. This means that the length of the tube is half of one wavelength of the fundamental. It turns out that a sousaphone is a variant on a tuba and is tuned to BBflat. So I looked up the data for such a tuba: the tube should be 5.5 metres long and will have a fundamental frequency of 29Hz. Now I'll check the data using v = f.lambda. If the tube length is half the wavelength, then lambda = 11m If speed of sound = 340m/s, then frequency = 340/11 = 31 metres. Not bad. It seems to work.