WHALE SONG WAVELETS

I’ve always liked to hear the whales sing and now Valerie clues us in on how there’s a visual representation…

“Whales and dolphins are accomplished vocalists, emitting complex patterns of clicks and whistles that vary in pitch, volume and length. To visualise their songs, and therefore identify species, marine biologists usually produce a spectrogram, a graph of how the frequency of their vocalisations varies over time. Spectrograms are created using a mathematical process called the Fourier transform (FT), which can convert raw sound into a set of sinusoidal waves. However, because these waves are periodic and infinite, they are better suited to describing repetitive, continuous noises, such as the whirr of a propeller, rather than the staccato clicks and whistles of cetaceans. Now Mark Fischer, an expert in marine acoustics, has come up with another way to illustrate whale song. He uses a more obscure method, known as the wavelet transform, which represents the sound in terms of components known as wavelets: short, discrete waves that are better at capturing cetacean song.” (Click here for more.)