Listener agreement on phonetic segments in early infant vocalizations

Noncry, nonlanguage vocalizations were sampled from four female babies between the ages of 7 and 21 months. Three trained listeners' phonetic transcriptions of more than 1,000 vocalizations were compared for interjudge and intrajudge agreement. The amount of agreement varied with the child's age and the criterion of agreement. The tendency toward somewhat greater interjudge agreement in the older than in the younger sampled months was attributed to the possibility that the child's vocal output becomes more speechlike with increasing age. Using an identical segment match criterion, interjudge and intrajudge agreement rarely exceeded 60% of the total number of segment comparisons made at any age. A feature-match criterion applied just to oral stops yielded higher agreement than did the identical segment match criterion. The results underscore the importance of considering listener reliability in assessing the validity of auditory descriptions of early vocal behavior and have implications for the methods used to describe auditory impressions.