The classroom is a common workplace integrating teaching staff and students. Both research and media report on the hampering effects of poor sound environments. According to Pellegrín-García (2011) it is not enough to treat the room acoustics. It is necessary to combine optimized acoustics with other preventive measures, such as vocal training and evidence-based tools to improve classroom communication in order to support teachers’ vocal health, well-being and students’ performance and study-environment.The purpose of this study is to explore the effects of an intervention program for teachers targeting classroom communication in different acoustic environments. Teachers (n=25) teaching in school year 3-6 participated in the program. Assessments were done pre/post intervention and at 5-weeks and 3-months follow-up. The teachers made self-assessments by answering questionnaires on vocal health, stress, burnout and self-efficacy. Their classrooms’ acoustics were measured for reverberation time and C50. The effects of the intervention showed significant results at follow-up: the teachers vocal health improved, and their perception of stress and burnout decreased while increasing their self-efficacy. There were also indications that the results of the effect differed depending on the room acoustics. The results of the intervention-program are promising and should be considered also in formal teacher education.