  Theoretical background: early verbal development is not yet fully understood,
especially in its formative phase. Research question: can a reliable,
easy-to-use coding scheme for the classification of early infant vocalizations
be defined that is applicable as a basis for further analysis of language
development? Methods: in a longitudinal study of 45 neurotypical infants, we
analyzed vocalizations of the first 4 months of life. Audio segments were
assigned to 5 classes: (1) Voiced and (2) Voiceless vocalizations; (3) Defined
signal; (4) Non-target; (5) Nonassignable. Results: Two female coders with
different experience achieved high agreement without intensive training.
Discussion and Conclusion: The reliable scheme can be used in research and
clinical settings for efficient coding of infant vocalizations, as a basis for
detailed manual and machine analyses.
