Bioacoustics Laboratory

The bioacoustics laboratory is equipped for sound analysis of a large variety of organisms. Investigations currently focus on studies of birds and bats. State-of-the-art recording and playback technology is available for audible sounds and ultrasound. For the work with sound archives, a specialized recording studio provides access to almost all types of historical recordings. The bioacoustics laboratory is closely linked to the Animal Sound Archive of the Museum für Naturkunde Berlin, one of the oldest and with about 120,000 sound recordings most extensive collections of animal sounds worldwide.

Methodology (selection):

• Digitisation of sound recordings
• Measurements in a low reverberation room
• Sound level measurements
• Acoustic analyses
• Measurement of hearing thresholds
• Playback experiments

Equipment (selection):

Recording studio
Sound engineer: Andreas Gnensch
The recording studio provides access to almost all historical recording media (analogue tapes, audio cassettes, DAT cassettes, audio CDs, vinyl records). It is equipped with professional studio devices (Studer and Revox), cassette decks, DAT recorders, CD players, record players, high-quality analogue-to-digital converters (RME ADI 96 Pro) and a mixing console.

Low reverberation room
A low reverberation room (acoustic half-space) with a volume of 26 cubic meters is available for acoustic measurements and calibration of measurement setups in an acoustically clean environment.

Acoustic recording and playback technology
The bioacoustics laboratory has recording, playback and measuring devices for audible and ultrasonic sounds which are used for laboratory tests and field work, including:
- Multi-channel recorder
- Long-term monitoring (Wildlife Acoustics SongMeter4 and SongMeterBat)
- Autonomous Ultrasound Detectors (Batlogger, Batcorder and AudioMoth)
- Ultrasonic microphones (Avisoft, Brüel & Kjær, GRAS and Knowles)
- Measurement microphones for frequency ranges up to 40 kHz
- Ultrasonic speakers (Avisoft and Apodemus)
- Software for acoustic measurements (Avisoft, Praat, MATLAB)

Measurement of hearing thresholds
The bioacoustics laboratory has mobile equipment for rapid measurement of hearing thresholds of small mammals. For this purpose, brain stem signals are detected using subcutaneous electrodes and analysed in real time. The obtained audiograms can be used to assess the hearing ability of animals. This information is important for subsequent playback experiments or acoustic analyses of communication sounds.

Applications (selection):

Bioacoustic monitoring (Frommolt Lab)
Bioacoustic methods are very well suited to record synchronously and continuously for any length of time occurrences, frequencies and behavioural patterns of individuals or populations and thereby aspects of biodiversity dynamics using standardized methods (Frommolt et al. 2017). The results obtained can be used to substantiate conservation decisions with verifiable observation data.

• Frommolt, K.-H. (2017). Information obtained from long-term acoustic recordings: applying bioacoustic techniques for monitoring wetland birds during breeding season. Journal of Ornithology 158: 659-668.

Acoustic communication and speciation (Mayer Lab)
Acoustically communicating grasshoppers and crickets are studied, aiming for a better understanding of how sexual selection can contribute or even accelerate speciation (Mayer et al. 2010, Berdan et al. 2015, Finck et al. 2016, Blankers et al. 2019). The following questions are addressed: How do acoustic signals (songs of males) differ between populations and species? Which song parameters are perceived by the females and what is their impact on the mating behaviour? What is the evolutionary time frame for the divergence of songs? And finally, what are the underlying evolutionary mechanisms, e.g. the role of geographic separation or the genetic architecture of acoustic traits?

• Blankers, T., E.L. Berdan, R.M. Hennig & F. Mayer  2019: Physical linkage and mate preference generate linkage disequilibrium for behavioral isolation in two parapatric crickets. Evolution doi:10.1111/evo.13706
• Finck, J., E. Berdan, F. Mayer, B. Ronacher & S. Geiselhardt 2016: Divergence of cuticular hydrocarbons in two sympatric grasshopper species and the evolution of fatty acid synthases and elongases across insects. Scientific Reports 6: 33695. doi: 10.1038/srep33695
• Berdan, E.L., C.J. Mazzoni, I. Waurick, J.T. Roehr & F. Mayer 2015: A population genomic scan in Chorthippus grasshoppers unveils previously unknown phenotypic divergence. Molecular Ecology 24: 3918-3930. doi: 10.1111/mec.13276
• Mayer, F., D. Berger, B. Gottberger & W. Schulze 2010: Non-ecological radiations in acoustically communicating grasshoppers? In: Evolution in Action – Case Studies in Adaptive Radiation, Speciation and the Origins of Biodiversity (Glaubrecht, M. Hrsg.). Springer, Berlin Heidelberg. 451-464. doi: 10.1007/978-3-642-12425-9_21.

Vocal learning and song dialects in bats (Knörnschild Lab)
Bats are among the few mammalian taxa capable of vocal learning (Knörnschild et al. 2010, 2012). Learning to sing by imitating conspecifics’ song often results in copying errors that can lead to pronounced regional dialects (Knörnschild 2014, Knörnschild et al. 2017). We study the acquisition, maintenance and functional significance of bat song dialects. In particular, we want to understand whether song dialects can accelerate speciation.

• Knörnschild M, Blüml S, Steidl P, Eckenweber E, Nagy M (2017) Bat songs as acoustic beacons – male territorial songs attract dispersing females. Scientific Reports 7: 13918.
• Knörnschild M (2014) Vocal production learning in bats. Current Opinion in Neurobiology 28: 80-85.
• Knörnschild M, Nagy M, Metz M, Mayer F, von Helversen O (2012) Learned vocal group signatures in the polygynous bat Saccopteryx bilineata. Animal Behaviour 84(4): 671-679.
• Knörnschild M, Nagy M, Metz M, Mayer F, von Helversen O (2010) Complex vocal imitation during ontogeny in a bat. Biology Letters 6(2): 156-159.

Frog calls as taxonomic characteristics (Rödel Lab)
The identification of different frog species, especially in the tropical species, is often difficult. While many species are similar in appearance, males' mating calls typically differ significantly, thus providing good taxonomic categorization features (e.g., Rödel et al., 2014, Günther et al., 2018). In the animal sound archive of the Museum für Naturkunde, these calls are deposited and kept publicly accessible. In addition to the taxonomic work with frog calls, scientists of the museum are also involved in the development of 'Best Practice' guidelines for recording and evaluating these calls and are investigating their evolution (Köhler et al., 2017).

• Günther, R., S. Richards & B. Tjaturadi (2018): Two new frog species from the Foja Mountains in north-western New Guinea (Amphibia, Anura, Microhylidae). – Vertebrate Zoology, 68: 109–122.
• Köhler, J., M. Jansen, A. Rodríguez, P.J.R. Kok, L.F. Toledo, M. Emmrich, F. Glaw, C.F.B. Haddad, M.-O. Rödel & M. Vences (2017): The use of bioacoustics in anuran taxonomy: theory, terminology, methods and recommendations for best practice. – Zootaxa, 4251: 1–124.
• Rödel, M.-O., M. Emmrich, J. Penner, A. Schmitz & M.F. Barej (2014): The taxonomic status of two West African Leptopelis species: L. macrotis Schiøtz, 1967 and L. spiritusnoctis Rödel, 2007 (Amphibia: Anura: Arthroleptidae). – Zoosystematics and Evolution, 90: 21–31.

Communication through vibration in insects (Hoch Lab)
Laser vibrometry (Conrad et al., 2016) and a magneto-dynamic transducer system are used to study the evolution of intraspecific communication through low-frequency vibration signals in selected model organisms (Insecta: Hemiptera). The results of these studies show, among other things, that a) speciation processes can be extremely fast (Hawaiian cave cicadas; Wessel et al. 2013), (b) subtroglophilic cicadas show special adaptations of their communication to their habitat (Hoch et al. 2013, Soulier-Perkins et al. 2015), and c) the specificity of the communication signals in fruit tree pests could play a role in their control (Eben et al., 2014).

• Conrad, T., Mühlethaler, R., Wessel, A. and Hoch, H. 2016. Laservibrometrie in der Insektenforschung. Laser Magazin 3, 2016.
• Eben, A., Mühlethaler, R., Gross, J. and Hoch, H. 2014. First evidence of acoustic communication in the pear psyllid Cacopsylla pyri L. (Hemiptera: Psyllidae). J. Pest Sci. 88(1): 87-95. DOI 10.1007/s10340-014-0588-0
• Hoch, H., Mühlethaler, R. and Wessel, A. 2013. Acoustic communication in the subtroglophile planthopper Trigonocranus emmeae Fieber, 1876 (Hemiptera: Fulgoromorpha: Cixiidae: Oecleini). Acta Musei Moraviae, Scientiae biologicae (Brno) 98(2): 155-162.
• Soulier-Perkins, A., Ouvrard, D., Hoch, H. and Bourgoin, T. 2015. Singing in the Namoroka Caves, First Record In Situ for a Cave Dwelling Insect: Typhlobrixia namorokensis (Hemiptera, Fulgoromorpha, Cixiidae). Journal of Insect Behavior 28(6); DOI: 10.1007/s10905-015-9531-3
• Wessel, A., Hoch, H., Asche, M., von Rintelen, T., Stelbrink, B., Heck, V., Stone, F.D. and Howarth, F.G. 2013. Founder effects initiated rapid species radiation in Hawaiian cave planthoppers. PNAS 110 (23) 9391-9396; https://doi.org/10.1073/pnas.1301657110