Bilateral syringeal interaction in vocal production of an oscine bird sound

Science  14 Mar 1986:
Vol. 231, Issue 4743, pp. 1297-1299
DOI: 10.1126/science.3945824


The vocal organ, or syrinx, of oscine birds has two parts, each of which has generally been presumed to operate independently of the other. A significant counter-example is now demonstrated in the production of a common vocalization by the black-capped chickadee (Parus atricapillus), in which the two acoustic sources interact in a nonlinear fashion. This bird produces a sound with multiple frequency components that are heterodyne products resulting from cross-modulation between two signals, thus providing evidence that avian phonation can involve cooperative coupling between the two syringeal sources.