Spectral slope discrimination in infancy: Sensitivity to socially important timbres

Spectral slope, the linear component of the spectral envelope, affects sound quality or timbre, and is important for object identification, speech discrimination, voice recognition, and interpreting vocal expressions of emotion. Eight-month-old infants discriminated between tones with spectral slopes of −10 dB/octave and −4 dB/octave, but not between positive or highly negative spectral slopes. Thus, the infant auditory system is tuned to be most sensitive to spectral slope differences in the range of those commonly found in speech and music.