Boucher, Ahmarani, & Ayad, 2006 Laryngoscope

Paper: V. J. Boucher, C. Ahmarani, and T. Ayad. Physiologic features of vocal fatigue: electromyographic spectral-compression in laryngeal muscles. Laryngoscope 116 (6):959-965, 2006. (note: I am going to start putting corresponding author's emails as found in the manuscripts)

Link to PubMed and abstract: PMID 16735908

First Commented on May 15, 2008

Overall Feeling: This is a nice cross over study using muscle fatigue knowledge as applied to laryngeal muscle fatigue. The protocol represents a significant amount of work that would be taxing to carry out (and to participate in). The study, and others like this, are needed.

Simply, they measured the muscle activity (EMG) of one of the vocal fold posturing muscles (the LCA) every 12-15 minutes throughout a day. Each measurement session was followed a 3 minutes loud (controlled) reading task.

First Comment: They took the time to use a nice sound level meter but never tell us about the room where recording took place. Was it an isolation booth? Low noise? Why did they spend so much time on the SLM and measures if they didn't tell us about the acoustics? This is just a minor comment.

Second Comment: I don't believe that this study could be done in the United States. Having worked with Institutional Review Boards, I don't believe that one would have thought the risk associated with that much EMG time (duration!- 12-14 hours of wires in my neck?) would be worth understanding vocal fatigue better (maybe vocal function as the larynx plays a necessary role in airway protection). The long term placement of electrodes, phsycological issues with all day placement, or potential drifting of electrodes with vibration from vocalization may cause additional damage or trauma and could eventually negatively effect the production of voice and the coordination of the system. While I hope the results are true (as they seem to be useful), I have a nagging thought that it might be induced by the all-day EMG electrodes...

Third Comment: Hind sight from a different lab is 20/20. Why did they choose 3 minute reading tasks at 12-15 minute intervals? Their goal was 50 but would 12 minute intervals result in an earlier occurrence of fatigue than 15 minute intervals? With slow fatiguing muscles of the larynx, would the extra 3 minutes make a difference? I would bet it would, effectively adding variability to their results. Also, they don't say why they chose that duration and interval. 3 minutes 50 times is 2.5 hours of speaking (speech accumulation time), similar to the time vocal loading of teachers found in other studies. That was a perfect setup that the authors missed in justifying why they chose it.



Possibly more later...