Fetal discrimination of low-pitched musical notes.

Cardiac responses of 36- to 39-week-old (GA) fetuses were tested with a no-delay pulsed stimulation paradigm while exhibiting a low heart rate (HR) variability (the HR pattern recorded when fetuses are in the 1f behavioral state). We examined whether fetuses could discriminate between two low-pitched piano notes, D4 (F(0) = 292 Hz/292-1800 Hz) and C5 (F(0) = 518 Hz/518-300 Hz). Seventy percent of all fetuses reacted to the onset of the first note (D4 or C5) with the expected cardiac deceleration. After heart rate returned to baseline, the note was changed (to C5 or D4, respectively). Ninety percent of the fetuses who reacted to the note switch did it with another cardiac deceleration. Control fetuses, for whom the first note did not change, displayed few cardiac decelerations. Thus, fetuses detected and responded to the pulsed presentation of a note and its subsequent change regardless of which note was presented first. Because perceived loudness (for adults) of the notes was controlled, it seems that the note's differences in F(0) and frequency band were relevant for detecting the change. Fetuses' ability to discriminate between spectra that lay within the narrow range of voice F(0) and F(1) formants may play an important role in the earliest developmental stages of speech perception.