Acoustic emission tests of sandstone specimens under uniaxial compression are carried out; and Kaiser point is determined by parameter method according to the principle of Kaiser effect. First

based on the above testing results

the energy distribution of acoustic emission signals is studied by means of the wavelet packet analysis technique; and regularity of energy distributions for different frequency bands is analyzed. The results show that the energy percentage of dominant frequency band at Kaiser point is significantly higher than other points. Then

relevant fractal dimensions of acoustic emission process are obtained by using G-P algorithm. Results show that the acoustic emission process is of obvious fractal characteristics. And the minimum value of relevant fractal dimension is at Kaiser point. The conclusion can be used to identify the characteristics at Kaiser point by waveform analysis.