The main aim of the project are concerned with the following 3 main topics: 1) Calibration of hydrophones for the frequency range between 20 Hz and 1 kHz Develop traceable measurement capabilities to meet the need for calibration of hydrophones at frequencies between 20 Hz and 1 kHz, and covering the 63 Hz and 125 Hz third-octave bands, as required by the guidelines for monitoring undersea noise within the EU Marine Strategy Framework Directive. 2) Calibration of autonomous noise recorders for the frequency range between 20 Hz and 1 kHz Develop calibration methods which provide traceable measurement capabilities to meet the need for calibration of autonomous underwater acoustic noise recording systems used for long-term ocean acoustic monitoring at frequencies between 20 Hz and 1 kHz, including the 63 Hz and 125 Hz third-octave bands for NMIs and DIs seeking to establish a research capability in this field 3) Creating Impact Develop an individual strategy for each participant for long-term operation of the developed measurement capabilities including regulatory support, research coll aborations, quality schemes and accreditation, contributing to development of a coherent metrology strategy for Europe within this field (discussed and agreed within the EURAMET community via the EURAMET TC-AUV), and significantly increasing the research capacity in the field.