22 Sep Parent Handouts DV AAC Posted at 04:15h in Blog by dvt BY 18 MONTHS babies have heard 4,380 HOURS OF SPOKEN LANGUAGE and we don’t expect them to be fluent speakers YET If AAC learners only see symbols modeled for communication twice weekly for 20-30 minutes, it will take 84 YEARS for them to have the same exposure to aided language as an 18 month old has to spoken language.