Abstract: A method of testing an elongate wooden element includes injecting an input acoustic signal into the element, detecting a return acoustic signal at a surface of the element, and determining a spectral profile for the return signal. In at least a predetermined range in the spectral profile, each resonance peak is detected whose amplitude exceeds a first predetermined value, and from the resonance peaks so detected the number of higher peaks is determined whose amplitude exceeds 3 dB. For each of said higher peaks a quality factor Q is calculated, a mean quality value Qm is determined, and Qm is then compared with a predetermined value to provide an indication of the presence or absence of external decay of the element. A ratio R of the number of higher peaks to the number of resonance peaks detected, and the statistical spread S of the average Q for the spectral profile, are calculated and compared with a predetermined boundary function Fn(R,S) to determine acceptability or unacceptability of the pole.

Abstract: A method of testing an elongate wooden element comprises injecting an input acoustic signal into the element, detecting a return acoustic signal at a surface of the element, and determining a spectral profile for the return signal. In at least a predetermined range in the spectral profile, each resonance peak is detected whose amplitude exceeds a first predetermined value, and from the resonance peaks so detected the number of higher peaks is determined whose amplitude exceeds 3 dB. For each of said higher peaks a quality factor Q is calculated, a mean quality value Qm is determined, and Qm is then compared with a predetermined value to provide an indication of the presence or absence of external decay of the element. A ratio R of the number of higher peaks to the number of resonance peaks detected, and the statistical spread S of the average Q for the spectral profile, are calculated and compared with a predetermined boundary function Fn(R,S) to determine acceptability or unacceptability of the pole.

Abstract: A two-way communication device includes a magnetoelastic rod located between an inertial back mass and a front panel of low mass. A coil is located in the vicinity of the rod, and the rod and coil together define an audio-electric transducer. An electronic processing circuit ensures that an audio-electric signal input to the device is applied to the coil to produce a sound wave from the low mass front panel and that when a sound wave impinges on the low mass front panel an audio-electric signal is produced and output from the device.

Abstract: A two-way communication device comprises a magnetoelastic rod (4) located between an inertial back mass (8) and a front panel (6) of low mass. A coil (13, 5) located in the vicinity of the rod (4), and the rod and coil together defining an audio-electric transducer. Electronic processing means ensures that an audio-electric signal input to the device is applied to the coil (13, 5) a sound wave is produced from the low mass panel (6) and when a sound wave impinges on the low mass panel (6) an audio-electric signal is produced which is output from the device.