There have been two interesting studies relating to throat clearing in the March edition of the Journal of Voice. Iwahashi et al (2017) explores the impact of throat clearing on the laryngeal structures. It begins with a comprehensive exploration of the link between voice disorders and habitual throat clearing. It cites several studies which link excessive throat clearing with the development of laryngeal granuloma. The study concluded that the ‘vocal fold velocity generated by throat clearing is sufficient to damage the laryngeal tissues.’ (770.e1) The cartilaginous portion of the vocal folds is more susceptible to impact stress than the membranous portion. This is because the cartilaginous portion has poor elasticity and is therefore vulnerable to injury thereby explaining the link between repeated throat clearing and granuloma. The study also concludes that this may be why hyperfunctional phonation is also harmful to laryngeal tissue.
Given the link between throat clearing and voice disorders, therapists are keen to suggest a range of alternatives. The second study by Shaw Bonilha et al (2017) researched the effectiveness of six throat clearing behaviours. These included:
- Hard coughing
- Hard throat clearing
- Silent coughing
- Soft throat clearing
- Dry swallowing
- Swallowing with a fluid bolus
This study examined the ‘mucus aggregation’ of 46 participants in total. 22 had voice disorders and 24 were vocally healthy. Stoboscopy recordings were taken before and after each of the six throat clearing behaviours. Each participant performed each clearing behaviour twice and two trained raters assessed the mucus aggregation for ‘type, thickness and pooling.’ (2017:252:e11). The results found that only the hard throat clearing changed the vocal fold mucus aggregation in both sets of participants. Surprisingly, coughing was not effective and the researchers speculate that the larger respiratory component involved in coughing may well cause new mucus to aggregate on the vocal folds.
The study concludes by discussing the implications for SLPs and ENTs who are responsible for treating voice disorders. The results of the study, albeit small scale indicate that alternative techniques are not effective. As coughing is more detrimental to the vocal folds than hard throat clearing, clinicians can advise to inhibit coughing.
There are potential implications of these two studies with the first one clearly indicating the harmful effects of throat clearing on the laryngeal tissues. The need to clear the throat is irresistible and for some habitual and therefore alternative strategies are very much needed. Perhaps the use of alternatives could be to break habitual patterns and minimise damage caused by the frequency of a such habits.
A Detailed Motion Analysis of the Angular Velocity Between the Vocal Folds During Throat Clearing Using High-speed Digital Imaging. Toshihiko Iwahashi, Makoto Ogawa, Kiyohito Hosokawa, Chieri Kato and Hidenori. Journal of Voice (2017)
Efficacy of Six Tasks to Clear Laryngeal Mucus Aggregation. Heather Shaw Bonhila et al. Journal of Voice (2017)