Table 1.

Source levels at 1.0 and 0.5 m from target microphone

Bat(s)	Source level at 1.0 m (dB SPLrms)	Source level at 0.5 m (dB SPLrms)	n (# of approaches)
Bat 1	86.8	81.0	1
Bat 2	70.0 ± 1.2	65.0 ± 2.2	3
Bat 3	85.4 ± 0.8	78.5 ± 1.0	3
Population	79.0 ± 3.2	73.1 ± 3.0	7

Mean source call levels with SEs at 1.0 and 0.5 m from target microphone. Data from individual bats and the population are shown. Due to no bat having called exactly 1.0 nor 0.5 m from the microphone, for each approach, a logarithmic regression formula obtained from calls emitted between 1.0 and 0.3 m was used to estimate the level of a call at 1.0 or 0.5 m from the microphone. The source level at 0.5 m is lower than at 1 m, because the bats have begun to echo intensity compensate (see Figure 1).