At four and a half, Anna was mostly incomprehensible. For example, in cardigan various properties of the G and N sounds got switched around. The effect was to make her incomprehensible, other than to those who knew her well, and wanted to understand her. Her treatment consisted in 14 half-hour sessions, each focusing on a different aspect of her speech.
In one session, close to the end of her treatment, when we had achieved most of our goals , I focused on the the final syllable of cardigan. The back of the tongue did not make a good contact with the roof of the mouth. After twenty trials, cardigan was now fully correct. After 14 sessions, she was fully comprehensible. Her speech was typical for a child of her age.