Infant speech development: A report of the study of one child by magnetic tape recordings

Using magnetic tape recordings—a new technology for that period 50 years ago—and a captive subject in his own home, Parmelee recorded his daughter's utterances and the sequences of speech development at monthly intervals during the first 2 years of her life. However, being the quintessential developmental pediatrician, Parmelee did not rely on the novel technological instrument alone. He also simultaneously recorded the social responsiveness, reciprocity, motor milestones, and feeding behaviors, all of which are intricately related in the development of speech. Through a correlation table, Parmelee illustrates that as his daughter's oro-motor mechanisms became more versatile with acceptance of a greater variety of food textures and emerging control over her mouth and jaw, her vocalizations became increasingly more complex. With the acquisition of progressive motor skills, such as mobility, her vocal-social development enlarged concomitantly within the wider world around her. Parmelee also noted changes in the tone and inflection of her speech, which became more interactive and sophisticated with age. Ultimately, despite technology, the human ear is called on to discern these nuances.