02540nas a2200241   4500008004100000022001400041245010300055210006900158260001600227300001600243490000800259520175600267653001302023653002302036653001302059653001202072653001902084653002002103100002102123700001402144700002002158856012002178       2008                        eng d  a0022-094900aCues for acoustic detection of prey: insect rustling sounds and the influence of walking substrate0 aCues for acoustic detection of prey insect rustling sounds and t  cJan-09-2008  a2799 - 28060 v2113 a<p>When insects walk, they generally produce sounds. These can reveal the walkers&#39; presence and location to potential predators such as owls, bats and nocturnal primates. Additionally, predators might extract information on taxon, palatability, size or profitability from the rustling sounds. In contrast to ear morphology, hearing physiology and psychoacoustics of acoustically oriented predators, little attention has hitherto been paid to the acoustic structure and information content of prey sounds. An important element in the ecology of acoustic prey detection remained virtually unexplored: the influence of the substrate type on rustling sounds. In this study, we analysed amplitude and frequency parameters from insects walking on various natural substrates, in both Germany (Carabus beetles) and Madagascar (various beetles and cockroaches). The data show that rustling sound amplitude and frequency content depend on substrate type. On moist substrates arthropods produced less intense and less broadband rustling sounds than on dry substrates. Sound pressure level was reduced by about 6 dB, halving the detection range for the predator. For a given insect, rustling sound amplitude increased with walking speed. Finally, we found that the previously established correlation of arthropod size and rustling amplitude holds across multiple substrates. Based on these data, we provide for the first time estimates of realistic detection distances in the field. These distances range from below 1 m to over 13 m, depending on the substrate, insect mass, walking speed and background noise level. These estimates are crucial for an understanding of the foraging ecology, foraging efficiency and sensory ecology of acoustic predators.</p>
10aauditory10adetection distance10aforaging10ahearing10aprey detection10asensory ecology1 aGoerlitz, H., R.1 aGreif, S.1 aSiemers, B., M.  uhttp://jeb.biologists.org/cgi/doi/10.1242/jeb.019596https://syndication.highwire.org/content/doi/10.1242/jeb.01959602214nas a2200229   4500008004100000022001400041245008800055210006900143260001600212300001600228490000800244520146400252653002101716653001801737653001201755653002501767653001901792100002101811700001501832700001701847856012001864       2008                        eng d  a0022-094900aComparing passive and active hearing: spectral analysis of transient sounds in bats0 aComparing passive and active hearing spectral analysis of transi  cMar-06-2009  a1850 - 18580 v2113 a<p>n vision, colour constancy allows the evaluation of the colour of objects independent of the spectral composition of a light source. In the auditory system, comparable mechanisms have been described that allows the evaluation of the spectral shape of sounds independent of the spectral composition of ambient background sounds. For echolocating bats, the evaluation of spectral shape is vitally important both for the analysis of external sounds and the analysis of the echoes of self-generated sonar emissions. Here, we investigated how the echolocating bat Phyllostomus discolor evaluates the spectral shape of transient sounds both in passive hearing and in echolocation as a specialized mode of active hearing. Bats were trained to classify transients of different spectral shape as low- or highpass. We then assessed how the spectral shape of an ambient background noise influenced the spontaneous classification of the transients. In the passive-hearing condition, the bats spontaneously changed their classification boundary depending on the spectral shape of the background. In the echo-acoustic condition, the classification boundary did not change although the background- and spectral-shape manipulations were identical in the two conditions. These data show that auditory processing differs between passive and active hearing: echolocation represents an independent mode of active hearing with its own rules of auditory spectral analysis.</p>
10abackground noise10acall analysis10ahearing10aperceptual constancy10aspectral shape1 aGoerlitz, H., R.1 aHubner, M.1 aWiegrebe, L.  uhttp://jeb.biologists.org/cgi/doi/10.1242/jeb.017715https://syndication.highwire.org/content/doi/10.1242/jeb.017715