Fig. 2. The intensity compensation behaviour of bat 1 while approaching the big sphere. (A) Emitted sound pressure level (SPL) per halving of distance is reduced by 4 dB (open diamonds); SPL incident on the target increases by 2.0 dB per halving of distance (filled squares). (B) Received SPL per halving of distance increases by 7 dB. The function of received SPL between 0 and 70 cm from target is given by: SPL_peak=-6.9xlog₂(d)+41.73, where d = distance (in m).