The Nature of Nasal Fricatives: Articulatory-Perceptual Characteristics and Etiologic Considerations

Abstract

Nasal fricatives (NFs) are unusual, maladaptive articulations used by children both with and without palatal anomalies to replace oral fricatives. Nasal fricatives vary in articulatory, aerodynamic, and acoustic-perceptual characteristics with two generally distinct types recognized. One type is produced with velopharyngeal (VP) constriction that results in turbulent nasal airflow and, frequently, tissue vibration (flutter) at the VP port. Trost (1981) described these as posterior NFs that have a distinctive snorting quality. A second type of NF is produced without significant VP constriction resulting in turbulent airflow generated at the anterior liminal valve of the nose. Of importance, both types are “active” alternative articulations in that the speaker occludes the oral cavity to direct all airflow through the nose (Harding & Grunwell, 1998). It is this oral gesture that differentiates NFs from obligatory (or passive) nasal air escape that may sound similar due to incomplete VP closure. The purpose of this article is to (1) describe the articulatory, aerodynamic, and acoustic-perceptual nature of NFs, and (2) propose a theoretical framework for the acquisition of NFs by children both with and without cleft palate.

Effect of motor‐based speech intervention on articulatory placement in the treatment of a posterior nasal fricative: a preliminary MRI study on a single subject

“…Motion artefact noted in the magnetic resonance images surrounding the velum indicated movement of this structure during productions of the posterior nasal fricative. This movement is likely related to the velar flutter that has been previously described during productions of the posterior nasal fricative (Zajac 2015). This provides anatomical evidence of a structure in motion while the child is producing the compensatory articulation error, which likely contributes to the perceptual phenomenon apparent during the production of a posterior nasal fricative.…”

“…Compensatory speech‐sound errors are frequently associated with VPD and palatal anomalies are often the primary cause of developing compensatory speech‐sound errors. However, compensatory speech errors can also be observed in patients who do not have a history of cleft palate, such as those who have frequent middle ear disease (Kuehn , Riski and Paone , Peterson‐Falzone and Graham , Zajac ).…”

“…Therefore, articulation and speech production requires a motor skill developed from a series of actions associated with practice or experience (Ruscello and Vallino ). Individuals who exhibit phoneme‐specific compensatory errors are reported to respond favourably to a motor‐based treatment approach (Ruscello and Vallino , Zajac ). A motor‐based approach is designed to teach the complex motor skill movement sequences required in the production of sounds (Ruscello ).…”

Obligatory Nasal Turbulence as a Trigger for the Development of Posterior Nasal Fricatives in a Child With Repaired Cleft Palate

“…Although the place of oral stopping can be variable—bilabial, alveolar, or velar—lingual-velar contact is most common (Peterson, 1975; Trost, 1981). The combination of relatively high driving air pressure and a relatively small VP port opening results in various degrees of turbulent airflow and tissue vibration or flutter (Trost, 1981; Zajac, 2015). Posterior nasal fricatives are typically used to replace sibilant and affricate sounds, although any of the fricatives may be affected (Peterson-Falzone and Graham, 1990).…”

“…A spectrogram of the nasal signal showed quasi-periodic energy consistent with tissue flutter (see Figure 4, p22). Because Zajac (2015) did not use imaging procedures, the source of the spectral flutter as velar could not be confirmed.…”