The underwater acoustic laboratory was established in 2017. It aims to implement the absolute calibration of hydrophone using laser heterodyne interferometry, which enables the sound pressure to be traced to SI via the wavelength of laser light, and shortens the traceability chain as well. At present, the optical calibration system covers the frequency range from 25 kHz to 500 kHz with measurement uncertainty less than 0.6 dB (k=2). We participated in the key comparison CCAUV.W-K2 with good results.
The anechoic room was established in 2006. The inner size of this lab is 14.0m×11.4m×8.8m with low cut-off frequency of 40 Hz and background noise of -2.4 dBA, which could provide the largest free-field acoustic region in China. A number of measurement services are conducted here every year, e.g. free-field calibration of microphone, sound power measurement and sound spectrum analysis, calibration of multi-sources positioning, noise reduction of hearing aid, record of Chinese national musical instruments, etc.