Malte Kob - mkob@ukaachen.de
Department of Phoniatrics, Pedaudiology, and Communication Disorders, RWTH Aachen University, Pauwelsstr. 30, 52074 Aachen, Germany
Gottfried Behler
Institute of Technical Acoustics, RWTH Aachen University, Germany
Anja Kamprolf, Christiane Neuschaefer-Rube, Oliver Goldschmidt
Department of Phoniatrics, Pedaudiology, and Communication Disorders, RWTH Aachen University, Germany
Popular version of paper 5pAA8
Presented Saturday afternoon, December 2, 2006, 2:45 pm
4th ASA/ASJ Joint Meeting, Honolulu, HI
Introduction
Professional voice users such as singers, teachers or call center agents rely on the performance of their voice. The acoustics of a room can restrict or support the singer or speaker and improve the sound of the voice and the intelligibility of speech. Previous studies found that teachers suffer more often from voice disorders than non-professional voice users. Our pilot study tries to find out whether disadvantageous acoustics in class rooms contributes to these findings.
Professional voice users such as singers, teachers or call center agents rely on the performance of their voice. The acoustics of a room can support the singer or speaker and improve the sound of the voice and the intelligibility of speech. Previous studies found that teachers suffer more often from voice disorders than non-professional voice users. Our study tries to find out whether disadvantageous acoustics in class rooms contributes to these findings.
For several reasons, the room acoustical conditions in class rooms are often not well adopted to the teaching task: poor sound insulation to school yards, corridors and neighboured rooms can produce additional noise which adds to the sound produced by the pupils in the class room. Often, the floor is not sufficiently or not at all covered. Some rooms show strong reverberance or even echoes which can make communication difficult. When the room acoustical support is rather weak, the voice performance can be strongly reduced, and more effort of the teacher is necessary to convey the speech to the listeners. The problem for the pupils is a reduced intelligibility of the teacher's speech which often causes a lack of attention and concentration resulting in worsening of the learning conditions. For the teacher, in a long term, this additional voice load can result in voice disorders such as hoarseness, voice fatigue and even force teachers to retire early from their profession.
Method and results
In the first part of our study the voice status of 25 teachers, the class rooms and the related teaching conditions in a primary school in Germany were investigated using standard methods applied by audiometrists, phoniatricians and speech therapists. In addition, an acoustical analysis of speech and voice samples was performed. From these investigations it was found that a significantly higher percentage of the teachers show voice problems in comparison to previous investigations of the prevalence of voice disorders in non-professional voice users. In figure 1 the results from the investigations of the teachers are depicted, classified according to the method of investigation and subclassified according to the result of the investigation of the voice status.
Figure 1: Results from various investigations, numbers are the percentage of a total of 25 teachers.
From all class rooms, four almost identical rooms were identified which exhibit unfavorable conditions for teaching: the reverberation times were increased, and the speech transmission indices were rather moderate. Two of these rooms were acoustically optimised by adding an absorbent layer to the ceiling and a carpet to the floor. In figure 2 the effect of a simulation of this modification on the reverberation time is shown. In the school, the rooms 1 and 2 were modified.
Figure 2: Prediction of reverberation time in class rooms under different conditions.
In the second part of the study, we tried to find an influence of the voice load during teaching sessions on selected properties of the teachers' voice. Four different sets of measurements were performed on each subject: before and after 1-6 hours of teaching in a rather reverberant room and in an acoustically optimized room. Preliminary results show that healthy teachers tend to raise the voice pitch in both types of rooms, whereas teachers with voice disorders or for which voice training is recommended, no average tendency was observed. The vocal sound pressure level mostly increased for members of the healthy group, whereas the group with voice training recommended, the voice level decreased in almost all cases. The acoustical analysis of the voice quality indicates that less than half of the healthy teachers' group showed a decrease of voice quality, whereas more than 50% of the group for which voice training was recommended showed a decrease of voice quality. Bad room a! coustical conditions increased that tendency for the group of non-healthy teachers stronger than for the group of healthy teachers.
Summary and outlook
The relation of room acoustics to voice problems of teachers in a primary school in Aachen, Germany, has been investigated in this study using an interdisciplinary collection of methods. In agreement with the well-known fact that the prevalence of voice disorders in teachers is increased compared to non-professional voice users our results show that a considerable fraction of the teachers examined in our study were suffering from voice disorders. It was demonstrated that class rooms with rather unfavorable room acoustics can be modified in such a way that the key parameters for improvement of communication are optimized. Further results indicate that teachers with different voice status seem to tolerate voice load during teaching differently. Differences in the room acoustical conditions in classrooms seem to affect teachers with voice problems more than healthy teachers.
We hope that this project contributes to a better understanding of the relation between room acoustics and the teacher's voice in class rooms. As a practical consequence, the conditions for this group of professional voice users could be improved by optimisation of the class room acoustics. However, bigger groups of teachers need to be investigated to obtain significant results. It was also found that voice analysis methods need to be further developed to improve their expressiveness and comparability among different research groups. The final goal is to help creating conditions in which the teacher's voice works well in every class room.