Vocal intensity in lecturers: Results of measurements conducted during lecture sessions

Abstract

Background: Occupational voice users (inter alia: lecturers) speak with different levels of vocal intensity. Speakers adjust this intensity knowingly (e.g. to underline the importance of fragments of the speech) or unknowingly. The unknown adjustment of voice intensity occurs e.g. in the presence of high acoustic background noise (so-called Lombard effect), but it also results from many other factors: hearing loss, construction of the vocal tract, habits and others. The aim of the article is to confirm the thesis that in similar conditions of acoustic properties of the room different lecturers speak with different levels of vocal intensity. Materials and Methods: The study was conducted in a group of 10 lecturers in the same conference room. A-weighted sound pressure level determined at 1 m from the lecturer's mouth was adopted as a parameter defining the intensity of the lecturer's voice. The levels of all lecturers' voice intensity were compared and evaluated according to the criteria defined in EN ISO 9921. Results: Nine in ten lecturers were speaking with normal voice intensity (60-65 dB) and only one full-time university lecturer was speaking with raised voice (66-71 dB). Conclusions: It was found that in the room of the same acoustic conditions the lecturers spoke with different intensities of voice. Some lecturers occasionally, and one all the time spoke with the voice intensity specified by PN-EN ISO 9921 as a raised voice. The results of the preliminary study warrant further studies in a larger group of teachers. Med Pr 2013;64(6):797–804

Keywords

• voice intensity level
• A-weighted sound pressure level of voice
• occupational voice
• Lombard’s effect