Single unit recordings are made from neurons in the auditory system of squirrel monkey. Species-typical vocalizations previously tape recorded are used as stimuli in a series of investigations aimed at disclosing systematic parameters of neural coding of this model language. Current work is focussed on testing the hypothesis that vocalization-specific feature detector cells exist at higher cortical levels exclusively. BIBLIOGRAPHIC REFERENCES: Alexander, G. E., Newman, J. D. and Symmes, D.: Convergence of prefrontal and acoustic inputs upon neurons in the superior temporal gyrus of the awake squirrel monkey. Brain Res. 115: 334-338, 1976. Newman, J.D. (Rapporteur): Biological filtering and neural mechanisms, Group Report. In Bullock, T.H. (Ed.): Recognition of Complex Acoustic Signals, Berlin, Dahlem Konferenzen, 1977.