The acoustic field in an asymmetric borehole was investigated by recording and comparing the waveforms with different offset in both axial symmetric borehole and axial asym-metric borehole. The two-dimensional spectrum in wave-number and frequency domain was also calculated and compared with the result of numeric simulation with 2.5-D finite difference method, and a consistent result was obtained. This work provides an accurate verification of our investigation of asymmetric borehole with 2.5-D finite difference method.