Patent ID: 7971485

Claim:
A method of testing an elongate wooden element, comprising injecting an input acoustic signal into the element, detecting a return acoustic signal at a surface of the element, determining a spectral profile for the return signal, detecting in at least a predetermined range in the spectral profile each resonance peak whose amplitude exceeds a first predetermined value, counting the number of said detected resonance peaks, determining from the resonance peaks so detected the number of higher peaks whose amplitude exceeds 3 dB, calculating for each of said higher peaks a quality factor Q, determining a mean quality value Q m , and comparing Q m with a predetermined value to provide an indication of the presence or absence of external decay of the element, calculating a ratio R of the number of higher peaks to the number of resonance peaks detected, calculating the statistical spread S of the mean quality value Q m for the spectral profile, and comparing the values of R and S with a predetermined boundary function F n (R,S) to determine acceptability or unacceptability of the elongate wooden element.