David J. Zajac, PhD, CCC-SLP, ASHA Fellow
The term “cleft palate speech” has often been used to refer to hypernasality, nasal air emission, reduced oral air pressure, and compensatory articulations of speakers who exhibit velopharyngeal inadequacy (VPI). Hypernasality is defined as excessive resonance of the nasal cavity during production of vowels and voiced consonants. Nasal air emission refers to the audible escape of air during the production of high-pressure oral consonants, especially voiceless consonants. Reduced oral air pressure is the flip side of nasal air emission. When air escapes through the nose, some oral air pressure is lost. Thus, oral pressure consonantsespecially voiceless ones—may be produced with reduced oral air pressure and perceived as weak or reduced in intensity. Compensatory articulations are maladaptive gestures that are produced at the glottis or in the pharynx as a way to circumvent a faulty velopharyngeal valve. The use of glottal stops to replace oral stops is a classic example of a compensatory articulation. Hypernasality, nasal air emission, and reduced oral air pressure are passive (or obligatory) symptoms of VPI. This means that the symptoms occur as a direct consequence of incomplete velopharyngeal closure. Compensatory articulations, however, are active (or learned) behaviors and may not occur in every individual.
Although obligatory nasal air emission is a core characteristic of VPI, many confusing, overlapping, and inaccurate terms have been used to describe its perceptual manifestation. The literature is replete with terms such as audible nasal air emission, nasal turbulence, nasal rustle, and passive nasal frication. Because the velopharynx and nasal passage are complex anatomical structures— which may be significantly altered due to both congenital defects and surgical interventions associated with cleft lip and palate—the variety of terms used to describe nasal air emission should not be too surprising. Numerous other terms have been used to describe nasal air emission that is part of active (or learned) nasal fricatives and will not be discussed here. The reader is referred to Zajac (2015) for a discussion of active nasal fricatives as an articulatory error. Rather, this article will focus on terminology used to describe passive or obligatory nasal air escape.
A Brief History of Current Terminology
McWilliams, Morris, and Shelton in the first and second editions of Cleft Palate Speech (1984, 1990) described nasal air emission as occurring along a continuum. First, it could be visible but inaudible, detectable only by holding a mirror under the nostrils of a speaker to see fogging as a result of the air emission. In such a case, the nasal airflow is laminar, moving in relatively smooth fashion, and does not become turbulent, or noise producing. Clinically, visible nasal air emission typically occurs in speakers who have adequate but not complete velopharyngeal closure and normal resonance. Although visible nasal air emission should be noted when it occurs in a speaker, there are no treatment implications. Continue reading