ABSTRACT
The 24th week of gestation marks the beginning of human fetal auditory responsiveness (Bernard & Sontag, 1947; Crade & Lovett, 1988). It is during the subsequent 15 weeks that sound exposure may have a pronounced effect on fetal behavior and central nervous system maturation. For example, speech perception and voice recognition in the newborn may result directly from repetitive, prosodic components of maternal speech heard by the fetus prenatally (Fifer & Moon, 1988). On the other hand, intense noises, as can be produced by vibrators and loudspeakers against the maternal abdomen, evoke unusual changes in fetal behavioral state and fetal movements that persist long after a very brief stimulus (Gelman, Wood, Spellacy, & Abrams, 1982; Visser, Mulder, Wit, & Prechtl, 1989). Periods of high-intensity airborne noise exposure in sheep increase the latencies in the fetal auditory brainstem response, suggesting some shift in the auditory threshold (Griffiths, Pierson, Gerhardt, Abrams, & Peters, 1994). Concerns about long-term fetal exposure to noise and vibration have been raised (Abrams & Wasserman, 1991; Gerhardt, 1990).
