Peripheral vocal mechanisms in birds: Are songbirds special?

This paper reviews recent advances regarding the peripheral mechanisms for song production by oscine songbirds and compares the vocal mechanisms of so ngbirds with those of certain non-oscines. The tracheobronchial syrinx of s ongbirds has several pairs of intrinsic muscles specialized for controlling particular aspects of sound production. The syringeal and vocal tract anat omy of non-oscines is much more diverse than that of songbirds and has fewe r or no intrinsic syringeal muscles. Often the same extrinsic tracheal musc les control both the temporal and spectral properties of vocalizations. Alt hough the vocalizations and vocal anatomy of these two groups are quite dif ferent, a number of motor patterns important in oscine song are also used b y non-oscines. These include special respiratory techniques, such as minibr eaths and pulsatile expiration, for sustained rapid vocalization, as well a s the ability to simultaneously produce two acoustically unrelated 'voices' . However, the complex syringeal musculature of songbirds with laterally in dependent motor control of each side of the syrinx provides a more versatil e vocal system in which the left and right sound sources can be coordinated in different ways, by specialized song control nuclei capable of vocal lea rning, to achieve diverse vocal effects.