State primary standard of units of sound pressure and vibrational velocity in aquatic environments GET 55-2025

The issues of calibration of underwater noise measurement instruments, which in modern hydroacoustics are represented by hydroacoustic measurement instruments – primary transducers and underwater measuring systems based on primary transducers, are considered. Much attention is paid to laboratory calibrations in water tank conditions of underwater measuring systems, the dimensions of which are several times larger than the dimensions of the primary transducers used in them. Such underwater measuring systems have signifi cant sensitivity nonuniformity, therefore their amplitude and phase frequency characteristics must be measured in a free fi eld with high frequency resolution and underwater measuring systems must be calibrated in frequency bands. The geographic range of application for hydroacoustic measurement instruments, from southern latitudes to northern ones (in the Northern Sea Route), requires studying the dependence of their metrological characteristics on changes in water temperature and excess hydrostatic pressure across the entire operating frequency range from a few hertz to hundreds of kilohertz. Modern underwater sonar and communication technologies require methods and instruments for measuring the phase sensitivity characteristics of primary transducers. To solve the above-mentioned issues, the State primary standard of units of sound pressure and vibrational velocity in aquatic environments GET 55-2017 was improved, which allowed the transfer of units only to primary transducers at one-third-octave frequencies and the calibration of primary transducer under excess pressure only in a limited frequency range of 5–500 Hz at water temperature of 15–25 °C. As a result of the conducted research, the metrological characteristics of the standard GET 55-2017 were improved and its functional capabilities were expanded, and the State primary standard of units of sound pressure and vibrational velocity in aquatic environments GET 55-2025 was approved. The stated goals were achieved through the inclusion in GET 55-2025 of new-generation measuring facilities and a unique hydroacoustic equipment complex developed at VNIIFTRI. The metrological characteristics of GET 55-2025 are presented. The reference facilities and hydroacoustic equipment included in GET 55-2025 are described. As a result, GET 55-2025 implements and ensures the reproduction and transfer of the unit of sound pressure in the aquatic environment with a minimum frequency step of 1 Hz in the range of 500–1·10⁶ Hz, studies of the characteristics of hydroacoustic measuring instruments in a free fi eld in the range of 2–500 kHz at an excess pressure of up to 15 MPa and an aquatic temperature of 4–35 °C, measurement of the phase-frequency characteristics of the sensitivity of primary transducers in the frequency range of 50–200 kHz, measurement of the frequency characteristics of the sensitivity of underwater measuring systems, the length of which does not exceed 3 m and weighing no more than 50 kg, in the frequency range of 1–250 kHz with a frequency resolution of 1 Hz, and also reproduction and transfer of the unit of the phase angle of sensitivity of primary transducers. GET 55-2025 ensured the principle of advanced development of metrology in hydroacoustics.

1. Biber A., Çorakçı A. C., Golick A. et al. Calibration standards for hydrophones and autonomous underwater noise recorders for frequencies below 1 kHz: current activities of EMPIR “UNAC-LOW” project. Acta IMEKO, 7(2), 32–38 (2018). https://doi.org/10.21014/acta_imeko.v7i2.542

2. Tarovik V. I., Savchenko O. V., Kutaeva N. G. Technogenic underwater noise as a factor in the environmental safety of maritime transport and industrial activities in the Arctic. Arctic: Ecology and Economy, 12(1), 99–110 (2022). (In Russ.) https://doi.org/10.25283/2223-4594-2022-1-99-110

3. Kuznetsov M. Yu., Polyanichko V. I., Ubarchuk I. A., Shevtsov V. I. Methodic recommendations for measuring underwater noise of research and commercial vessels. Izvestiya TINRO, 205(1), 179–194 (2025). (In Russ.) https://doi.org/10.26428/1606-9919-2025-205-179-194 ; https://elibrary.ru/yopamo

4. Ford B., Robinson S. P., Ablitt J. A Study of the stability exhibited by hydrophones when exposed to variations in temperature and hydrostatic pressure. Proceedings of Meetings on Acoustics Acoustical Society of America, 44(1), 070024 (2021). https://doi.org/10.1121/2.0001491

5. Guanghui J., Yi Ch., Dong Zh. Free-field three-transducer spherical-wave reciprocity calibration for hydrophone at hydrostatic pressure of 10 MPa. Journal of Physics: Conference Series, 2756(1), 012044 (2024). https://doi.org/10.1088/1742-6596/2756/1/012044

6. Losev G. I. Peculiarities of algorithms of spectral analysis of vector-phase measurements of hydroacoustic field parameters. Proc. Of the XXXIV session of Russian Acoustical Society, Moscow, 14–18 February 2022, pp. 278–285. GEOS Publishers, Moscow (2022). (In Russ.) https://www.elibrary.ru/edugzw

7. Isaev A. E., Matveev A. N., Nekrich G. S. et al. State primary standard GET 55-2017 for units of sound pressure and vibrational velocity in a water medium. Izmeritel’naya Tekhnika, (8), 3–5 (2017). (In Russ.) https://elibrary.ru/zgwhaj

8. Isaev A. E., Kuznetsov S. I., Lomovatskiy Y. A. et al. VNIIFTRI reference base in the field of underwater acoustic measurements: metrological characteristics, functional capabilities, innovations, and prospects for improving standards. Izmeritel’naya Tekhnika, 73(12), 46–54 (2024). (In Russ.) https://doi.org/10.32446/0368-1025it.2024-12-46-54 ; https://elibrary.ru/dkwbov

9. Bobber R. J. Underwater electroacoustic measurements. Golenkov A. N. (eds.), Mir Publ., Moscow (1974). (In Russ.)

10. Isaev A. E. Metrology of hydroacoustic measurements. Precise free-field calibration of underwater sound receivers. In 2 vol. FSUE VNIIFTRI, Mendeleevo (2023). (In Russ.)

11. Isaev A. E., Matveev A. N., Strelov S. V. et al. Key comparison CCAUV.W-K2: features of hydrophone calibration. Izmeritel’naya Tekhnika, 73(1), 67–72 (2024). (In Russ.) https://doi.org/10.32446/0368-1025it.2024-1-67-72 ; https://elibrary.ru/fbxacj

12. Isaev A. E. Accurate calibration of sound pressure receivers in an aquatic environment under free field conditions. FSUE VNIIFTRI, Mendeleevo (2008). (In Russ.)

13. Isaev A. E., Matveev A. N. Calibration of hydrophones in a field with continuous radiation in a reverberating pool. Acoustical physics, 55(6), 762–770 (2009). https://doi.org/10.1134/S1063771009060104

14. Isaev A. E., Nikolaenko A. S. Laboratory free-field calibration of a hydroacoustic receiver at low frequencies. Izmeritel’naya Tekhnika, (1), 54–59 (2018). (In Russ.) https://elibrary.ru/ynugap

15. Jia G., Chen Y., Fei T. et al. A technical discussion about COOMET pilot comparison results of sound pressure sensitivity and sound pressure gradient sensitivity in frequency range 5 Hz to 400 Hz. 48th International Congress and Exhibition on Noise Control Engineering “INTER-NOISE 2019 MADRID”, Madrid, Spain, 2019. https://www.elibrary.ru/lxkpaa

16. Chen Y., Jia G.-H., Fei T. et al. The pilot comparison calibration of vector receivers in the frequency range 5 Hz to 10 kHz. Jiliang Xuebao/Acta Metrologica Sinica, 41(10), 1279–1283 (2020). https://doi.org/10.3969/j.issn.1000-1158.2020.10.16

17. Isaev A. E., Yi C., Matveev A. N. et al. Results of pilot comparisons of amplitude–phase calibrations of hydrophones in the frequency range 10–500 kHz COOMET 786/RU-a/19. Izmeritel’naya Tekhnika (3), 67–72 (2023). (In Russ.) https://doi.org/10.32446/0368-1025it.2023-3-67-72 ; https://elibrary.ru/kkodvh

18. Kalyu V. A., Krasnopistsev N. V., Losev G. I. et al. Comparison of the results of measurements of the source underwater noise levels obtained by the direct method and using vector-phase processing. Proceedings of Krylov State Research Centre, (3(401)), 121–127 (2022). (In Russ.) https://doi.org/10.24937/2542-2324-2022-3-401-121-127 ; https://elibrary.ru/bnmhgk

19. Matvienko Yu. V., Khvorostov Yu. A., Kamorny A. V. Experimental studies of scalar-vector sound receiver operation in the modes of underwater noise source detection and direction finding. Podvodnye issledovaniia i robototehnika, (3(53)), 31–39 (2025). (In Russ.) https://doi.org/10.37102/1992-4429_2025_53_03_03 ; https://elibrary.ru/nrfodq

20. Wood N. An overview of the calibration process for a digital hydrophone. The Journal of the Acoustical Society of America, 155(3_Supplement), A349–A349 (2024). https://doi.org/10.1121/10.0027789