There was greater variation in the 63-Hz third-octave band than in the 125-Hz band. This was also found elsewhere at a coastal site 60 m deep in the USA, where the median 63-Hz and 125-Hz levels were similar, but the 95th percentile level was louder in the 63-Hz band
This increased variation may be due to the influence of local shipping as commercial ships typically produce louder sound levels within the 63-Hz band as compared to the 125-Hz band
With increased variability in the 63-Hz band mean levels as compared to the 125-Hz band, longer monitoring to determine statistically significant trends may be required. Similarly, a greater number of samples throughout the year may be required for the 63-Hz band to ensure a representative sample as supported by the sampling effort
analysis.