Quantifying the impact of vocal loading

The daily data collected by the voice dosimeter for each teacher allowed the researcher to compare the recorded vocal load during working and non-working hours (see graph below). "There are marked differences during working and non-working hours. This demonstrates that teaching is particularly vocally demanding," states Angélique Remacle.

In general, average frequency for a woman varies between 200 and 250 hertz (Hz). This means that in one second, a woman's vocal cords vibrate 200 to 250 times. Therapists are able to measure this frequency during consultations by asking their patients to produce a long vowel sound like "a." Yet the averages the researcher recorded in her study are higher that those recorded in consultation. The average frequency for teachers at work is around 260 Hz as compared to 240 Hz outside of work. Similarly, the vocal intensity of teachers at work is 80 decibels (dB) as compared to 75 dB outside of work. Teachers therefore really do speak more softly and at a lower frequency when they are not at work. During a typical workday, a teacher's vocal cords vibrate 1/5 of the time. This is significant, especially given that these daily figures must be cumulated in order to get a clear picture of the work the larynx performs in a week. In the best-case scenario, teachers are only able to rest their voices over the weekend in order to recover before starting a new workweek. This estimate is cut in half when the teacher is not working, since phonation occurs only 1/10 of the time.

The dosimeter  also allowed Ms. Remacle to evaluate the number of glottal cycles; that is, the number of vocal folds vibrations over time. During the workday, teachers' vocal cords vibrate more than a million times, and another half a million times outside of work. Over the course of an entire day, this can add up to 1.5 million vibrations. As a comparison, this is as if the vocal folds travelled the equivalent of 5 km per day. These figures taken together all show how vocally demanding the teaching profession is. In an occupational setting, kindergarten and elementary school teachers use their voice more often and at a higher intensity and frequency than in non-occupational settings.