Acoustical characteristics of vocalizations of sows, piglets, and nursery pigs under selected husbandry practices were analyzed with a digital signal processing system. The duration (D) and major energy-resonance frequency (P) for each call were determined as follows: a) processing of piglets (D = 0.81 s and f* = 3 700 Hz); b) food anticipation of breeding-gestation sows (2.50 s and 3 000 Hz); c) isolation of piglet (0.34 s and 500, 3 500 Hz); d) startling of nursery pigs (0.29 s and 900 Hz); e) sows in heat (3.07 s and 1 375 Hz); f) farrowing (0.10 s and 3 000 Hz); g) sow nursing (0.15 s and 1 000 Hz); and h) mate greeting of sow (0.13 s and 1 000 Hz). Calls a) to d) are responses to human generated stressors, and calls e) through h) responses to social and physiological states of the pigs. Thus, vocalizations can be segmented for different pig production situations.