# Panel Sound Absorber

 A panel Absorber is created when you place a sheet of plywood or fibreboard, with insulation glued to the back of it, over an air cavity. The panel will have a resonate frequency of its own, tap it and you will hear it. When it is placed over a sealed cavity, and insulation is attached to the back, everytime it hears its own note it resonates and the air in the cavity resonates and the insulation absorbs the resonance, hence absorbing the frequency! It is important to note that here we have an absorber that reflects the high frequencies and attenuates the low. With the hangers all that exposed insulation absorbs the high frequencies as well so the panel absorber has a place in the studio. The three factors determining the frequency of absorption are: The weight of the panel. The depth of the air cavity, i.e. depth of the sealed timber frame. Use of absorption material Filling the cavity with fibreglass or mineral wool tends to lower the resonant frequency by up to 50 per cent as well as doubling the effectiveness of the trap. It also lowers the Q of the trap so that it is effective over a wider frequency range. A typical panel-type trap is effective for frequencies around one octave either side of the centre frequency, which at least has the advantage that you don't have to be absolutely accurate to get results.

## Calculate Frequency of absorption

 Panel width : cm Panel height : cm Panel weight : Kg Panel depth : cm Panel area is m2 A fixed panel with concealed cavity has its natural frequency at Hz A panel fixed and concealed cavity filled with absorbers has a expected frequency at Hz

## Calculate Panel depth

 Panel width : cm Panel height : cm Panel weight : Kg Panel frequency should be : Hz Panel depth is cm Panel area is m2 A fixed panel with concealed cavity has its natural frequency at Hz A panel fixed and concealed cavity filled with absorbers has a expected frequency at Hz

## Calculate Panel mass

 Panel width : cm Panel height : cm Panel depth : Kg Panel frequency should be : Hz Panel mass is Kg Panel area is m2 A fixed panel with concealed cavity has its natural frequency at Hz A panel fixed and concealed cavity filled with absorbers has a expected frequency at Hz

Working priciples of panel absorbers - Video 28:42 minutes

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