How silent are ERGOVENT gypsum diffusers?

ERGOVENT RONDO diffusers operate at an extremely low noise level. The design incorporates aerodynamic improvements that significantly reduce airflow resistance and noise. Made from gypsum, these diffusers also possess acoustic properties that help absorb sound, making them quieter than traditional metal diffusers. In a quiet room environment, the operation of the RONDO or KVADRO diffuser is hardly noticeable, provided there is no additional noise from the duct system itself.