In 1998 I started an engrossing email correspondence with Willis Pitkin:

When infants reach a certain age, they start babbling; if an infant can hear, this babbling continues and becomes more elaborate and articulate, but if the infant is deaf, it stops.

Will’s hypothesis was that what made the difference was the absence of auditory feedback.; he proposed that sound be converted into a visual form and presented to deaf infants, allowing them to have the feedback they’d otherwise lack.

Because of my background in the visual display of sound (and especially, in dealing with speech in ways other than by speaking or hearing and in aural cognition by infants ), I was very interested to talk to Will about this; one of the issues we discussed was the cognitive importance of the “now” moment. As an experiment, I made a version of the Music Animation Machine display in which there was no view of the future, and the more recent notes were larger than those in the past.

Will is currently looking for parents who'd like their deaf child to have the experience of seeing pretty colors and patterns whenever they vocalized.