Phoneme-specific nasal [air] emission (PSNE) is a learned articulation pattern that mimics velopharyngeal inadequacy (VPI). Also called pseudo VPI by some, the distinctive perceptual characteristic of PSNE has been variously described as a nasal snort, posterior nasal fricative, and/or nasal rustle. As described below, the defining characteristic of PSNE appears to be the simultaneous production of both an oral stop and posterior nasal fricative as a substitution for any of the fricative, sibilant, and/or affricate sounds. As a substitution that occurs in the presence of normal velopharyngeal closure for stop-plosive sounds, PSNE should logically be considered a learned phonological error.

Based upon the literature and our clinical experience at the UNC-CH Craniofacial Center, children who employ a pattern of PSNE typically exhibit a history of the following:

• Phonological disorder

• Frequent middle ear infections and/or conductive hearing loss

• Tonsillectomy and/or adenoidectomy

Typically, these children have had a history of speech therapy that may have resulted in overall articulation improvement except for the pattern of PSNE. Often, these children are then referred to craniofacial specialists to rule-out structural problems.  Although PSNE can occur in a child with repaired cleft palate, the majority of children that we have seen do not have overt or submucous clefts of the palate.

The cause of PSNE is unclear (see Peterson-Falzone & Graham [1990] for a review of possible etiologies).  PSNE may represent a transitional stage between the phonological process of stopping and the normal production of fricatives.  This explanation is appealing in that many children with PSNE also have a history of other phonological processes. Sensory/perceptual deficits also may contribute to the development of PSNE. This, too, is an appealing explanation given that children with PSNE also tend to have early and frequent episodes of conductive hearing loss. It is possible that children with chronic conductive hearing loss may prefer velopharyngeal frication because of increased auditory feedback via bone conduction.  Obviously, these two etiologies may not be mutually exclusive.

Finally, subtle structural anomalies may also contribute to the development of PSNE. As indicated above, many children have had histories of tonsillectomy and/or adenoidectomy. It is possible that obstructing tonsils and/or an irregular adenoid pad may facilitate nasal escape during the early acquisition of sibilants. Again, this explanation may not be mutually exclusive of those described above.

The clinical diagnosis of PSNE is dependent upon a good history to identify possible contributing factors. A good clinical ear (and eye) is also necessary to discern the co-produced oral and nasal components. During mirror testing, a  child with PSNE will exhibit visible/audible nasal escape only during fricative, sibilant, and/or affricate sounds, not during stop plosives. Some children may also present with mild hypernasality. Typically, accompanying hypernasality is due to assimilation to vowels produced adjacent to the affected consonants with PSNE.

Because of the perceptual saliency of the nasal emission aspect of PSNE, the oral stop component is often difficult to identify. Because of this, we often use the headset of the Nasometer to simultaneously record the separate oral and nasal acoustic signals to aid in differential diagnosis. Below, we present a case of PSNE that was recorded in this manner.

Case 1

As illustrated, the oral (red) waveform shows clear acoustic stop gaps that are characteristic of stop-plosive consonants. Note that the first syllable shows some acoustic energy during the stop segment prior to oral release. This most likely was due to acoustic crossover from the nasal microphone.

The mixed signal represents what the ear hears as PSNE during production of /s/. Nasal air emission is perceptually salient.

The nasal microphone signal reveals a co-produced posterior nasal fricative (or nasal snort) as a substitute for the alveolar fricative. The boy also tended to exhibit a nasal grimace during production of the nasal fricative, perhaps to further achieve perceptual characteristics of /s/ by narrowing the anterior exit of the nose and increase turbulence. Indeed, a LPC spectrum of the nasal fricative shown below indicates spectral energies approximately in the range expected for /s/ (above 4-5 kHz). In addition, the spectrum shows a low frequency component that is expected due to the posterior source of turbulence.  

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