Purpose This study examined how lexical representations and intervention intensity affect phonological acquisition and generalization in children with speech sound disorders. Method Using a single-subject multiple baseline design, 24 children with speech sound disorders (3;6 to 6;10 [years;months]) were split into 3 word lexicality types targeting word-initial complex singleton phonemes: /ɹ l ʧ θ/. Specifically, academic vocabulary words, nonwords (NWs), and high-frequency (HF) words were contrasted. Intervention intensity was examined by comparing the performance of 12 children who completed eleven 50-min sessions (4 children/word type) to the performance of 12 who completed 19 sessions (4 children/word type). Children's production accuracy of their treated phonemes and overall percent consonants correct values were used to measure phonological generalization via percentage accuracy scores and d scores. Results All word lexicality conditions elicited phonological change, suggesting that academic vocabulary words, NWs, and HF words are viable intervention targets. Group mean averages were similarly high for the NWs and HF words, although children in the NW condition demonstrated more consistent phonological gains. Children who received 19 intervention sessions achieved 6 times more gains in treated sound accuracy than did children who received 11 sessions. Conclusions Word lexicality did not significantly influence children's intervention outcomes. More intensive intervention, as characterized by the number sessions, resulted in greater phonological change than did a shorter intervention program. Intervention intensity outcomes should be considered when establishing best practices for speech intervention scheduling. Supplemental Material https://doi.org/10.23641/asha.7336055

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.