DOI: 10.5061/dryad.ngf1vhhv3
title: Echolocation call parameters of Daubenton's bats during exposure to masking noise

description: Echolocating bats hunt prey on the wing under conditions of poor lighting
 by emission of loud calls and subsequent auditory processing of weak
 returning echoes. To do so, they need adequate echo-to-noise ratios (ENRs)
 to detect and distinguish target echoes from masking noise. Early obstacle
 avoidance experiments report high resilience to masking in free-flying
 bats, but whether this is due to spectral or spatiotemporal release from
 masking, advanced auditory signal detection or an increase in call
 amplitude (Lombard effect) remains unresolved. We hypothesized that bats
 with no spectral, spatial or temporal release from masking noise, defend a
 certain ENR via a Lombard effect. We trained four bats (Myotis
 daubentonii) to approach and land on a target that broadcasted broadband
 noise at four different levels. An array of seven microphones enabled
 acoustic localization of the bats and source level estimation of their
 approach calls. Call duration and peak frequency did not change, but
 average call source levels (SLRMS, at 0.1 m as dB re. 20 μPa,
 root-mean-square) increased, from 112 dB in the no-noise treatment, to 118
 dB (maximum 129 dB) at the maximum noise level of 94 dB. The magnitude of
 the Lombard effect was small (0.13 dB SLRMS/dB of noise), resulting in
 mean broadband and narrowband ENRs of -11 and 8 dB respectively at the
 highest noise level. Despite these poor ENRs, the bats still performed
 echo-guided landings, making us conclude that they are very resilient to
 masking even when they cannot avoid it spectrally, spatially or
 temporally.
description: The dataset consists of echolocation call parameters from
 Daubenton's bats (<em>Myotis daubentonii</em>). These
 calls were recorded with an array of seven microphones during controlled
 behavioural experiments in which the bats were exposed to four different
 levels of broadband, ultrasonic noise. The task that bats were trained to
 complete was to fly across an anechoic room while using echolocation
 and land on a spherical transducer that could emit the noise.
description: There are 5 different datasets: 1.
 'atrack_info.mat' (for Matlab): each row corresponds to one
 trial which was either without noise ('noise level'=20) or had
 one of the four different levels of noise. The 'calls' column
 contains call parameters while the 'loctrack' contains
 localization parameters for these calls. 2.
 'full_dataset.csv': this dataset was generated after selecting
 specific calls from each trial in the 'atrack_info.mat'. These
 calls can be found in the 'indfinal1' field of the column
 'loctrack' in 'atrack_info.mat'. 3.
 'dataset_sl.csv': this dataset was generated from
 'full_dataset.csv' after selecting the five calls of each trial
 with the highest SL<sub>RMS </sub>('sl').
 4. 'dataset_enr.csv': this dataset was generated from
 'full_dataset.csv' after selecting the five calls of each trial
 with the highest
 broadband ENR<sub>BB </sub>('enrb').
 5. 'dataset_tc.csv': this dataset has only one row per
 trial and it contains the time needed for each bat to complete the landing
 task ('time_flight_s').