In the previous two articles in this series we examined the evidence concerning the clinical indictors of coughing and a runny nose. The conclusion was, both indicators provide us with weak information concerning swallowing function. In this edition, the evidence for wet vocal quality as a meaningful clinical finding will be discussed.
At one time scientists thought (and taught us) that wet vocal quality (WVQ) following a swallow was an important clinical sign of dysphagia. It was thought that this finding was distinct from other voice disturbances and was identified as “wet” or “gurgly” during phonation.1, 2 It was thought that this vocal change occurred because the bolus entered the larynx.1 This led to diet changes and clinical recommendations.
However, even as speech pathologists were being taught to fear WVQ, a publication in 1988 reported only 31.8% of people who aspirated exhibited this finding on a clinical swallow examination.3 Numerous other studies have discussed concerns regarding variable rater reliability for WVC.4, 5, 6
Two controlled studies have examined the ability of therapists to connect WVQ with aspiration.
The first recorded voices immediately after subjects completed swallowing a bolus while performing 23 video fluoroscopic swallow studies. The subjects were instructed to produce a prolonged “ahh.” Three speech pathologists with “extensive” experience in dysphagia evaluation were asked to judge the recording. The presence of wetness was determined if at least two of the three judges agreed. The results indicated that identifying the presence of a wet voice as a symptom of penetration/aspiration is poor. The authors suggest that a wet voice may be more predictive of saliva and/or mucoid secretions in the airway than prandial material. Changing diets will not lead to changes in these areas. The author goes on to explain there is often increased saliva production after neurologic damage occurs. The seminal conclusion of the article is “a wet voice was not associated with residue in the larynx or trachea or with ingested material in the oropharynx.” 7
A second study, used the same basic method. Seventy-eight subjects had a videofluoroscopic study with simultaneous recording of acoustic data of post swallow phonation. Again, five “experienced” therapists rated randomized audio samples. The conclusion was that average clinicians do not reliably perceive WVQ when material is present in the larynx during phonation.8
Speech pathologists have spent many years honing our skills of observation. The take away from this three part review of “clinical signs of aspiration” is coughing, runny nose and wet vocal quality are not reliable tools to make inferences concerning the physiology of the swallow. Although wet voice may make the SLP uncomfortable, research proves that it cannot be used as a reliable clinical indicator of aspiration or penetration. All roads lead to this fact: imaging is the only way to determine swallowing physiology.
1. Logemann, J. (1998). The Evaluation and Treatment of Swallowing Disorders. Austin, TX; Pro-Ed.
2. Murray, J., Langmore, S., Ginsberg, S., Dostie, A. (1996). The significance of accumulated oropharyngeal secretions and swallowing frequency in predicting aspiration. Dysphagia, 11, 99-103.
3. Horner, J., Massey, W., Riski, J., Lathrop, M., & Chase, K. (1988). Aspiration following stroke: Clinical correlates and outcome. Neurology, 38, 1359–1362
4. DeBodt, M., Wuyts, F., Van de Heyning, P., Croux, C. (1997). Test-retest study of the GRBAS scale; Influence of experience and professional background on perceptual rating of voice quality. Journal of Voice, 11, 74-80.
5. Dejonkere, P., Obbens, C., deMoor, G., & Wieneke, G.(1993). Perceptual evaluation of dysphonia: Reliability and relevance. Folia Phoniatrica, 45, 76–83.
6. Kreiman, J., & Gerratt, B. (2000a). Sources of listener dis-agreement in voice quality assessment Journal of the Acoustical Society of America, 108, 1867–1876.
7. Warms, T., Richards, J. (2000) “Wet Voice” as a predictor of penetration and aspiration in oropharyngeal dysphagia. Dysphagia,15(2):84-8.
8. Groves-Wright, K., Boyce, S., Kelchner, L. (2010).Perception of Wet Vocal Quality in Identifying Penetration/Aspiration During Swallowing. Journal of Speech, Language, and Hearing Research. Vol. 53, 620-632