Possible Clues:

• Elocutionary peculiarities
• Struggles with sigmatism
• Says I'm thick, when I'm not well?
• Cases for speech therapy
• Subjects of some therapy sessions
• 'Frontal' or 'lateral' speaking features
• Speech-language pathologist's concerns
• Speech therapists' concerns
• Certain speech impediments
• Imitates Daffy Duck, in a way