Acoustics Flashcards
What is sound insulation
The amount of sound energy that is blocked by a certain construction
What is the difference between structure borne and air borne sound
Air borne is generated by sound waves travelling in air and consequently through a construction
Structure borne is sound generated mechanically, by excitation of the construction directly
What are the three types of sound transmission
Direct, flanking, and indirect
What is direct transmission
Sound transmission directly through the partition wall between two rooms
What is flanking transmission
Arise from bending waves in flanking walls travelling towards flanking walls in receiver room
What is indirect transmission
Transmission of sound via air cavities, suspended ceilings and hallways
What is the density of air at 20 degrees
1.21 kg/m3
What is the relation of the mass of a wall with its airborne sound insulation
The hogher the mass, the larger its inertia, therefore the mire energy it takes to make it vibrate therefore the higher the airborne sound insulation
Is low freq or high freq sound more easily transmitted through a wall
Low freq
If a single leaf wall’s mass is doubled or the frequency of incident sound is doubled, what is the difference in siund insulation
6 db
The bigger the angle of incidence the (blank) the sound insulation
Worse
If a single leaf wall has R=40 for normal incidence, what is its R for random incidence
Aproximately 35 db
What is the value of pc in the theoretical mass law equation
410
