Investigating the reliability of the hydrophone model proposed in VNIIFTRI, consisting of an advance line and a minimum-phase part, including sound diffraction effect and resonance properties of the active element, is one of the COOMET 786/RU/19 pilot comparisons' responsibilities. This model allows for inverse operation, and the employment of the Hilbert transform to generate a phase-frequency response from the amplitude-frequency response. This study presents experimental results from the facilities of the State Primary Standard of units of acoustic pressure and vibrational velocity in an aqueous medium GET 55-2017. Obtaining the phase-frequency response for an acoustic center of the receiver is not essential for numerous practical applications. Therefore it is sufficient to determine the shape of the phase-frequency response using far less laborious methods.