Speech-language pathology (or alternatively speech-language therapy) is a field of expertise practiced by a clinician known as a Speech-language pathologist (SLP), also called speech-language therapist, or speech therapist, who specializes in the evaluation and treatment of communication disorders and swallowing disorders.
Speech-language therapists, in both Federation Starfleet and Lyran Starfleet, were in short supply, alongside the medical professions which are together designated as allied healthcare professions. As with other allied healthcare professionals, speech-language therapists were assigned in priority to starbases and to hospital ships, in that order. (Star Trek: False Vacuum: "Wagon Train to the Stars")
Surprisingly, unlike other allied healthcare professions, Lyrans had less trouble recruiting speech-language therapists for military service than the Federation did. (Star Trek: False Vacuum: "No plot? No problem!")