Effects of sound amplification on teachers' speech while teaching

Voice problems are common among teachers. This is most likely due to the heavy vocal load of their profession. The present study investigated one possible method to decrease the vocal load. The effects of amplification on classroom speech were studied on five Icelandic teachers (three females, two males, mean age 51 years). Classroom speech was recorded with a portable DAT recorder and a head-mounted microphone, first under ordinary conditions and in the next week while using electrical sound amplification. The average fundamental frequency (F0), sound pressure level (SPL) and phonation time were measured. According to the results, amplification significantly lowered both F0 (average 8.6 Hz for the females and 11.3 Hz for the males, p = 0.002 and 0.0001, respectively) and SPL (about 1 dB for both genders, p < 0.05), while phonation time was not significantly affected. The results suggest that electric amplification is likely to reduce vocal load.