Abstract We numerically investigate the effects of spectrophone parameters, including the operating acoustic frequency, the relative position of the quartz tuning fork and the excitation laser beam, the gap between the resonant tubes and the tuning fork, and the diameter and length of the resonant tubes, on the performance of gas sensors based on quartz-enhanced photoacoustic spectroscopy. A pair of rigid tubes with inner diameter of 0.2 mm and length of 5.1 mm, placed 0.6 mm down from the opening and 20 μm away from the edge of the tuning fork, is suggested for optimal performance.