Source levels

The table shows source levels (SL) for search calls of 11 species of bats. Frequency(maxE) is the frequency with maximum energy in their calls. Source levels are pooled in two distance groups, 0–5 m and 5–10 m, according to the bat's distance from the microphone array. For 0–5 m, the table gives median values of all (n) source level estimates within this range. dB/dd is the increase in source level per distance doubled (dd) at short distances from trend lines in Fig. 2. For 5–10 m, the table gives two averages: Avg SL, the average of all (n) call estimates within this range, and Avg maxSL, average of the maximum source level from each approach flight (N). Overall maximum source levels at each distance range is shown with an asterisk: *max. Averages and standard deviations were calculated from sound pressure levels in Pa, but given here as dB SPL. Thus, standard deviations are not symmetrical and only the positive SDev is given. For species abbreviations: see Fig. 1