Development of Simultaneous Pitch Encoding: Infants Show a High Voice Superiority Effect

Department of Psychology, Neuroscience & Behaviour, McMaster University, Hamilton, Ontario L8S 4K1, Canada.
Cerebral Cortex (Impact Factor: 8.67). 03/2013; 23(3):660-669. DOI: 10.1093/cercor/bhs050
Source: PubMed


Infants must learn to make sense of real-world auditory environments containing simultaneous and overlapping sounds. In adults, event-related potential studies have demonstrated the existence of separate preattentive memory traces for concurrent note sequences and revealed perceptual dominance for encoding of the voice with higher fundamental frequency of 2 simultaneous tones or melodies. Here, we presented 2 simultaneous streams of notes (15 semitones apart) to 7-month-old infants. On 50% of trials, either the higher or the lower note was modified by one semitone, up or down, leaving 50% standard trials. Infants showed mismatch negativity (MMN) to changes in both voices, indicating separate memory traces for each voice. Furthermore, MMN was earlier and larger for the higher voice as in adults. When in the context of a second voice, representation of the lower voice was decreased and that of the higher voice increased compared with when each voice was presented alone. Additionally, correlations between MMN amplitude and amount of weekly music listening suggest that experience affects the development of auditory memory. In sum, the ability to process simultaneous pitches and the dominance of the highest voice emerge early during infancy and are likely important for the perceptual organization of sound in realistic environments.

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    • "This is a critical issue because the stimuli in some previous studies included inappropriate chords, but insufficiently considered differences in melody in the highest voice. A harmonic progression is comprised of multiple voice parts and is accompanied by prime melodies of the highest voice, typically the most noticeably perceived voice (Fujioka et al., 2005; Marie and Trainor, 2012). For this reason, there is a high probability that ERAN can result from both irregular chord function and differences in the highest voice in a chord progression, i.e., melody. "
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    • "However, as noted by recent investigators (e.g., Fujioka et al., 2005, 2008; Marie and Trainor, 2013), given the asymmetric shape of the auditory filters (i.e., peripheral tuning curves) and the well-known upward spread of masking (Egan and Hake, 1950; Delgutte, 1990a,b), these explanations would, on the contrary, predict a low voice superiority. As such, more recent theories have largely dismissed these cochlear explanations as they are inadequate to account for the high voice prominence reported in both perceptual (Palmer and Holleran, 1994; Crawley et al., 2002) and ERP data (Fujioka et al., 2008; Marie and Trainor, 2013). "
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