The absorption ratio of a surface is the ratio of _______

_______________ system is just the reverse of the exhaust system.

Sound foci is a defect caused by _________ interior surfaces.

Concrete floor floating construction provides good insulation against ______ sounds.

For working a temperature of 21 degree Celsius, range of 30% to 70% of ________ is desirable.

The auditorium rear wall should be concave in shape.

In _________ system, some mechanical arrangement is adopted to provide enough ventilation to the room.

Which of the following is not an acoustical defect?