02214nas 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