Table of contents |
2 Voice production 3 Loading on tissue in vocal folds 4 Effect of speaking environment 5 Symptoms 6 Voice care |
Voiced speech is produced by air streaming from the lungs through the vocal cords setting them into an oscillating movement. In every oscillation, the vocal folds are closed for a short period of time. When the folds reopen the pressure under the folds is released. These changes in pressure form the waves called (voiced) speech.
The fundamental frequency of speech for an average male is around 110Hz and for an average female around 220Hz. That means that for voiced sounds the vocal folds will hit together 110 or 220 times a second, respectively. Suppose then that a female is speaking continuously for an hour. Of this time perhapse five minutes is voiced speech. The folds will then hit together more than 30 thousand times an hour. It is intuitively clear that the vocal fold tissue will experience some tiring due to this large amount of hits.
Vocal loading includes also other kinds of strain on the speech organs. These include all kinds of muscular strain in the speech organs, similarly as usage of any other muscles will experience strain if used for an extended period of time. However, in respect of vocal loading research largest interest lies in stress exerted on the vocal folds.
Several studies in vocal loading show that the speaking environment does have a significant impact on vocal loading. Still, the exact details are debated. Most scientists agree on the effect of the following environmental properties
Background
Of the working population, about 15% have professions where their voice is their primary tool. That includes professions such as teacher, sales personnel, actors and singers, and TV and radio reporters. Many of them, especially teachers, suffer from voice related medical problems. In a larger scope, this involves millions of sick-leave days every year, for example, both in the US and the European Union. Still, research in vocal loading has often been treated as a minor subject.Voice production
Loading on tissue in vocal folds
Effect of speaking environment
In addition, smoking and other types of air pollution might have a negative effect on voice production organs.