A self-contained unit for the demonstration of the methods of noise and vibration control. An integral 240v electric motor and gearbox together with a 12v fan unit provide two noise sources. Variable control of both voltage sources allows speed control of both motors.
Each of two microphones may be connected to a dBA filter and illuminated bar display to show relative loudness.
A rigid enclosure with acoustic lining may be placed over either noise source and attachments allow investigation of sound attenuation in ducts.
Resilient mountings and mount bypass equipment allows investigation of modes of vibration at various frequencies and transmission of noise through solids.
The unit enables the following demonstrations to be carried out.
Attenuation of a mechanical or aerodynamic noise source using a rigid enclosure and combining this with an absorbent acoustic lining.
The rapid degeneration in effectiveness of the above enclosure method due to minor imperfections in construction.
The transmission of noise along ducts and methods of attenuation using acoustic linings.
The transmission of noise along solid paths and the methods of reduction by isolation.
The effect of the noise frequency on the effectiveness of attenuation methods.
Rigid body modes of vibration of a resiliently mounted source and the effects of mass variation of the resonant frequencies and modes of vibration
A: 300W 220/240 Volts, 50Hz. (With earth/ground)
B: 300W 110/120 Volts, 60Hz. (With earth/ground)