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Table 2. Indicates the discrepancy of a night's average background noise level from the station's quietest night (blue numbers). Data from Station 7 after May 11-12 was compomised by a damaged microphone. The initial equipment configuration for Station 4 had a 43.74 dB quietest night. An equipment change on May 11-12 led to an inherently higher recording level, which had a quietest night of 46.74 (measured during 2nd quiet period). A microphone change at Station 6 on May 19-20 led to an ~1 dB quieter recording level (i.e., 39.66 quietest night in 2nd quiet period) from that night onward. Light orange cells indicate a night when the background level was 3 dB to 6 dB louder than the station's quietest night. Darker orange-shaded cells indicate a night when background level was 6 dB or louder than the station's quietest night. Light blue cells indicate nights when an average background level equalled that station's quietest night of the study period. The purple SD1 column shows the inter-station standard deviation of the background noise discrepancy for each date with number of nights figured in parentheses. The pink SD2 row shows the intra-station standard deviation for all the nights recorded at each station (number of nights in parentheses).