寻求不依赖于实验室标准传声器的灵敏度而直接溯源至国际单位制基本单位的声压量值复现技术是声学计量的长期目标，对声压量值摆脱实物基准具有重要意义，激光多普勒测速技术是实现这一目标的有效途径。以行波管内平面波声场为测量对象，建立无固定频移的激光多普勒测速系统，采用光子相关光谱分析法解调多普勒信号，获得声管内示踪粒子的振动速度，根据平面波声压与质点振动速度的线性关系，复现声管测量点处的声压。以工作标准传声器的测量结果为参考，评估测量方案的可行性和测量结果的准确性，分析影响测量准确性的主要因素。测量结果表明，声波频率为315 Hz，声压级在100 dB~110 dB范围内间隔1 dB变化时，测量偏差小于0.5 dB；声压级为105 dB，声波频率为315，400，500，800 Hz时测量偏差小于0.3 dB。

It is a long-term goal and of great significance to seek a new method towards direct realization of the SI unit of sound pressure and no longer rely on the sensitivity of standard laboratory microphone in the field of airborne acoustic metrology. Laser Doppler velocimetry technique can be used to realize the goal. In this paper, the optical interferometer without Doppler frequency bias is designed to investigate the realization of sound pressure in traveling wave tube with the photon correlation spectroscopy (PCS). According to the linear relationship, the sound pressure of plane acoustic wave can be acquired by the demodulated particle vibration velocity from the Doppler signal. The experiments are also implemented to demonstrate the feasibility and accuracy of this scheme with the working standard microphone as reference. For the acoustic frequency of 315 Hz, the deviation between the two methods is less than 0.5 dB with the measured sound pressure level varied every 1 dB in the range from 100 dB to 110 dB. For the measured sound pressure level of 105 dB, the deviation is less than 0.3 dB with acoustic frequency of 315, 400, 500, and 800 Hz.