Analysis and synthesis of humpback whale songs.

Abstract

The humpback whale song is one of the most complex, non-human, acoustic displays in the animal kingdom. In this paper, we analyze and synthesize the humpback song using additive synthesis which is one of the most powerful techniques for the analysis, modification, and synthesis of complex audio or speech signals. This method creates complex sounds by adding together individual sinusoidal signals called “partials.” A partial’s frequency and amplitude are each time-varying functions, so it is a more flexible version of the harmonic associated with a Fourier series decomposition of a periodic waveform. Applying the fast Fourier transform to all overlapping frames (small time segments), we can detect peaks from the frequency spectrum of each frame and calculate the frequency, magnitude, and phase for all the peaks. These extracted parameters are then used as components of the sinusoidal signals (partials) for the synthesis process. This process finally reconstructs and concatenates each frame, generating the synthesized humpback song. We observed that this synthesized song resembles much more closely the original humpback song by the time/frequency domain representation and listening. In the future, we will analyze and synthesis other baleen whale songs with this powerful synthesis method. [Work supported by IITA (IITA-2008-(C1090-0801-0039)).]