Intervention dose frequency: Phonological generalization is similar regardless of schedule

This study examined how intervention dose frequency affects phonological acquisition and generalization in preschool children with speech sound disorders (SSD). Using a multiple-baseline, single-participants experimental design, eight English-speaking children with SSD (4;0 to 5;6) were split into two dose frequency conditions (4 children/condition) targeting word-initial complex singleton phonemes: /ɹ l ʧ/. All children received twenty 50-minute sessions that were either provided twice a week (2×/week) for ten weeks or four times a week (4×/week) for five weeks. Tau-U effect sizes for two generalization measures, treated phoneme and percent consonants correct (PCC), were calculated for each participant. Group d-scores were calculated to measure generalization of the treated phoneme in untreated words for each condition. All eight children demonstrated gains in their phonological measures. Two children in 2×/week condition demonstrated significant changes in generalization of treated phonemes in untreated words. One child in each condition demonstrated significant changes in PCC scores. Group d-scores were similar suggesting children in both conditions generalized their treated phoneme in untreated words to a similar level. Regardless of whether speech intervention occurred 2×/week or 4×/week, children demonstrated similar phonological gains. This suggests that both dose frequencies are viable intervention schedules for preschoolers with SSD. Children in the 4×/week condition made their phonological gains in approximately half the time of children in the 2×/week condition. Thus, more frequent weekly speech intervention sessions could be more efficient in teaching phonological information than less frequent sessions.