The CNHS locations also had negligible barriers to sound, and no intervening large bodies of water. At and above 63Hz, both the A- and C-weighted SPL modeling used the same octave band data from manufacturers. As manufacturers did not provide 16 and 31.5Hz octave band sound power levels, measured data (Keith et al., 2016) were used in these octave bands for the modeling. At all frequencies the measured 1/3 octave band data were also used to identify, and correct for, significant discrete frequency components that could affect the conversion from the A- to C-weighted data.