Language and Speech: Distinguishing Between Aphasia, Apraxia, and Dysarthria in Music Therapy Research and Practice

ABSTRACT: Music therapists can play a significant role in the treatment of communication disorders. Understanding the distinction between language and speech, however, is critical to evaluating the effectiveness of treatment. This article reviews the definitions and characteristics of adult onset aphasia, apraxia, and dysarthria and outlines the distinctions necessary for music therapists to know and use. Current information regarding music therapy and music-related therapy techniques is included. Music therapists can play a significant role in the treatment of communication disorders. Understanding the distinction between language and speech, however, is critical to evaluating the effectiveness of music therapy. Clients who demonstrate increased intelligibility through singing may not have an understanding of the words they are producing, while other clients may have ideas they are unable to express. The definitions used for speech and language disorders are part of the problem; speech-language pathology literature does not use consistent terminology. More important, for music therapists, is the lack of a comprehensive model that integrates current knowledge of the neuroscience of speech and language, and an understanding of the process of communication, with the music therapy strategies that can have an impact on these areas. This article focuses on a single issue that would be part of such a model: the distinctions between adult-onset aphasia, apraxia, and dysarthria and the implications of those differences on music therapy research and practice. Principles of Verbal Communication The American Speech-Language-Hearing Association describes the distinction between speech and language this way: "Language is a code made up of rules that include what words mean, how to make words, how to put them together, and what word combinations are best in what situations. Speech is the oral form of language" (ASHA, 2004). Language can be expressed in many ways, including alternative and augmentative communication. The act of verbal communication is a complicated process, from the conceptualization of an idea and the production and articulation of speech sounds by one person to the reception of those sounds and comprehension of their meaning by another. Dronkers and Ogar (2004) described the expressive act as follows: "Thoughts must be translated into linguistic representations (itself not a trivial feat), which are then sent to speech mechanisms that can coordinate, initiate, modify and execute the articulation of an utterance" (p. 1461). Researchers and writers have described the process of verbal communication both in conceptual and neurological terms. Sperber (1995) has provided an informal picture: if Jill wants to communicate some meaning to Jack, she looks up in her mental grammar of English the sound associated to that particular meaning, and produces that sound for Jack to hear. Jack then looks up in his mental grammar the meaning associated with that particular sound. In that manner, Jack finds out what Jill had in mind. Of course, all this "looking-up" is automatic and unconscious (except when you can't find your words, and become painfully aware of searching for them). Thanks to this double conversion-the encoding of meaning into sound, and the decoding of sound into meaning-Jill and Jack are now sharing a thought, (p. 191) Peach (2004) has reviewed two more formal models of the communication pathway that include at least three steps: a central language processing area selects phonemes' to represent thought and then sends neural codes to a motor planning center, which, in turn, activates the muscles needed to produce speech sounds in the correct order. Speech itself involves the rapid sequencing of two motor acts: sound and gesture. It depends on the repetition of learned movement patterns, the ability to initiate new movements, and the brain's ability to be flexible in how it achieves particular vocal and articulatory results (Barlow, Parley, & Andreatta, 1999). …