Bionic marvel: what do Bose Wave systems and whooper swans have in common?

If you ever saw Bose infomercials about their Wave music systems you probably remember the well-illustrated explanations of how the Waveguide system actually works. To summarize these principles, I will use a few quotes from the company’s site:

“They realized that by mounting a loudspeaker in a tube, the motion of the loudspeaker would act as a waveguide, effectively transforming a small amount of input (air) into a large amount of output (sound). Drs. Bose and Short discovered that a waveguide could match the mechanical properties of a loudspeaker for efficient operation over a wide range of notes.”

“Additional analysis and measurements revealed that the tube could be folded into intricate patterns with no ill effect on sound quality. This discovery eliminated any concerns about the length of the waveguide and proved to be an extraordinary breakthrough.”




Now, here is the amazing connection. For centuries there was a belief that swans are capable of producing most melodious songs only when they are about to die. All this despite the fact that ordinarily swans are not known to be particularly inclined to sing well or to sing at all! This legendary trait, however, has been surprisingly confirmed in the nineteenth century for whooper swans (C. cygnus), one of the two species that were observed, but not distinguished between, in antiquity. Because of the “remarkably shaped trachea, convoluted inside its breastbone” the whooper’s expiring breath produces soft tones, similar to a flute (see Arnott, W. G. 1977. “Swan Songs.” Greece & Rome 24:149–153). It is possible that the legend about swan songs goes back to one very observant hunter a few thousand years ago who, after shooting a swan, heard these soft tones (which also may have happened to be even more sonorous than usual). It seems, without too much simplification, that the Bose Waveguide system uses the very same acoustic principle!