AbstractThis paper presents a new methodology for detecting the longitudinal location of the hidden hole in a log using impact-echo testing. The hole and the end surface of the log produced two different amplitude peaks in the frequency spectrum after a mechanical tap on the top of the log. The ratio of the two frequencies was used to estimate the longitudinal position of the hole. The major advantage of this method is that it avoids measuring the travel velocity of the stress wave, which is sensitive to many factors and then poses a formidable challenge to the realization of inspection. Experimental studies were carried out using Pine logs with mechanically drilled holes and a Cinnamomum camphora log with natural hole. The results indicated that the estimated positions were in good agreement with the actual position of the hole. The impact-echo testing can be applied to detect the longitudinal position of the internal hole in log.