Acoustic measurements. The sound level meter or the equivalent measuring system, including the windscreen recommended by the manufacturer shall meet or exceed the requirements of Type 1 instruments in accordance with IEC 61672-1:2013. The measurements shall be made using the frequency weighting A, and the time weighting F. When using a system that includes a periodic monitoring of the A-weighted sound level, a reading should be made at a time interval not greater than 30 ms.
Acoustic measurements. 6.2.1.1. When no general statement or conclusion can be made about conformance of the sound level meter model to the full specifications of IEC 61672-1:2013,4 the apparatus used for measuring the sound pressure level shall be a sound level meter or equivalent measurement system meeting the requirements of Class 1 instruments as described in IEC 61672-3:20134. Measurements shall be carried out using the "fast" response of the acoustic measurement instrument and the "A" weighting curve as described in IEC 61672-1:20134. When using a system that includes a periodic monitoring of the A-weighted sound pressure level, a reading should be made at a time interval not greater than 30 ms. When measuring the rated sound frequency (or frequency range), the digital sound recording system shall have at least a 16-bit quantization. The average auto power spectrum shall be determined, using a Xxxxxxx window and at least 66.6 per cent overlap averages and cover the relevant frequency band. The instruments shall be maintained and calibrated in accordance with the instructions of the instrument manufacturer.
Acoustic measurements. The primary purpose of acoustic monitoring is to empirically verify modeled injury and behavioral disturbance zones (defined at radial distances to NMFS-specified thresholds; see Estimated Take by Incidental Harassment). For non-pulsed sound, distances will continue to be evaluated for attenuation to the point at which sound becomes indistinguishable from background levels. Empirical acoustic monitoring data will be used to document transmission loss values determined from past measurements and to examine site-specific differences in SPL and affected ZOIs on an as needed basis. Should monitoring results indicate it is appropriate to do so, marine mammal mitigation zones may be revised as necessary to encompass actual ZOIs. Acoustic monitoring will be conducted as specified in the approved Monitoring Plan. Please see Table 2–2 of the Plan for a list of equipment to be used during acoustic monitoring. Monitoring locations will be determined based on results of previous acoustic monitoring effort and the best professional judgment of acoustic technicians. For activities such as demolition of the old fuel pier and temporary mooring dolphin, the Navy will continue to collect in situ acoustic data to validate source levels and ZOIs. Environmental data would be collected including but not limited to: Wind speed and direction, air temperature, humidity, surface water temperature, water depth, wave height, weather conditions and other factors that could contribute to influencing the airborne and underwater sound levels (e.g., aircraft, boats). Full details of acoustic monitoring requirements may be found in section 4.2 of the Navy’s Monitoring Plan. Visual Marine Mammal Observations The Navy will collect sighting data and behavioral responses to construction for marine mammal species observed in the region of activity during the period of activity. All observers will be trained in marine mammal identification and behaviors and are required to have no other construction-related tasks while conducting monitoring. The Navy will monitor the shutdown zone and disturbance zone before, during, and after pile driving as described under Mitigation Measures and in the Monitoring Plan, with observers located at the best practicable vantage points. Notional monitoring locations are shown in Figures 3–3 and 3–4 of the Navy’s Plan. Please see that plan, available at xxx.xxxx.xxxx.xxx/xx/ permits/incidental/construction.htm, for full details of the required marine mammal monitori...
Acoustic measurements. 6.2.1.1. When no general statement or conclusion can be made about conformance of the sound level meter model to the full specifications of IEC 61672-1:2013,3 the apparatus used for measuring the sound pressure level shall be a sound level meter or equivalent measurement system meeting the requirements of Class 1 instruments as described in IEC 61672-3:2013.3 Measurements shall be carried out using the "fast" response of the acoustic measurement instrument and the "A" weighting curve as described in IEC 61672-1:20133. When using a system that includes a periodic monitoring of the A-weighted sound pressure level, a reading should be made at a time interval not greater than 30 ms. When measurements of the sound pressures in the one-third mid-band frequencies 2,000, 2,500 and 3,150 Hz are carried out for one-third octaves, the instrumentation shall meet all requirements of IEC 00000-0-0000, class 1. The sound pressure level in the mid-band frequency 2,500 Hz shall be determined by adding the quadratic means of the sound pressures in the one-third mid-band frequencies 2,000, 2,500 and 3,150 Hz. When measuring the rated sound frequency (or frequencies), the digital sound recording system shall have at least a 16 bit quantization. The average auto power spectrum shall be determined, using a Xxxxxxx window and at least 66.6 per cent overlap averages. The instruments shall be maintained and calibrated in accordance with the instructions of the instrument manufacturer.
Acoustic measurements
