02432nas a2200241   4500008004100000022001400041245014400055210006900199260002000268300001600288490000800304520158900312653001801901653002501919653001201944653001201956653002201968653002301990100002002013700001902033700001802052856012002070       2013                        eng d  a0022-094900aMaintaining acoustic communication at a cocktail party: heterospecific masking noise improves signal detection through frequency separation0 aMaintaining acoustic communication at a cocktail party heterospe  cOct-24-20132050  a4655 - 46650 v2163 a<p>We examined acoustic masking in a chirping katydid species of the Mecopoda elongata complex due to interference with a sympatric Mecopoda species where males produce continuous trills at high amplitudes. Frequency spectra of both calling songs range from 1 to 80 kHz; the chirper species has more energy in a narrow frequency band at 2 kHz and above 40 kHz. Behaviourally, chirper males successfully phase-locked their chirps to playbacks of conspecific chirps under masking conditions at signal-to- noise ratios (SNRs) of &minus;8 dB. After the 2 kHz band in the chirp had been equalised to the level in the masking trill, the breakdown of phase-locked synchrony occurred at a SNR of +7 dB. The remarkable receiver performance is partially mirrored in the selective response of a first-order auditory interneuron (TN1) to conspecific chirps under these masking conditions. However, the selective response is only maintained for a stimulus including the 2 kHz component, although this frequency band has no influence on the unmasked TN1 response. Remarkably, the addition of masking noise at 65 dB sound pressure level (SPL) to threshold response levels of TN1 for pure tones of 2 kHz enhanced the sensitivity of the response by 10 dB. Thus, the spectral dissimilarity between masker and signal at a rather low frequency appears to be of crucial importance for the ability of the chirping species to communicate under strong masking by the trilling species. We discuss the possible properties underlying the cellular/synaptic mechanisms of the &lsquo;novelty detector&rsquo;.</p>
10aambient noise10aauditory interneuron10ainsects10akatydid10anovelty detection10aselective encoding1 aSiegert, M., E.1 aRömer, Heiner1 aHartbauer, M.  uhttp://jeb.biologists.org/cgi/doi/10.1242/jeb.089888https://syndication.highwire.org/content/doi/10.1242/jeb.089888