Like speedy96, I have been building a plane wave tube (aluminium) to calibrate some pinhole plugs with a sensor below the pinhole cavity against another accurate sensor.
I have built a wooden tapered contraction (or fitting) for the speaker to connect to the tube directly. Does it have to be of specific shape or design? May I know how is the shape going to determine how does the plane wave propagate? I am now trying a design with plywood and also hopefully it might be rigid enough at the resonance region of the speaker. I don't quite understand how the flare of the speaker is applied here if anyone can explain that to me?
Secondly, the sound absorption material at the termination end, I am currently using two wedge for the upper and lower surface. Due to the small tube (using it for high frequency application in wind tunnel) and short of time to source good acoustic foam provider as they don't cut such small foams, I could only make it on two surface. Would that be sufficient?
I have built a wooden tapered contraction (or fitting) for the speaker to connect to the tube directly. Does it have to be of specific shape or design? May I know how is the shape going to determine how does the plane wave propagate? I am now trying a design with plywood and also hopefully it might be rigid enough at the resonance region of the speaker. I don't quite understand how the flare of the speaker is applied here if anyone can explain that to me?
Secondly, the sound absorption material at the termination end, I am currently using two wedge for the upper and lower surface. Due to the small tube (using it for high frequency application in wind tunnel) and short of time to source good acoustic foam provider as they don't cut such small foams, I could only make it on two surface. Would that be sufficient?