Abstract
Cave crawling in zebra finch skulls: what is the functional interaural canal?
Ole Næsbye Larsen, Rasmus Salomon, Kenneth Kragh Jensen, and Jakob Christensen-Dalsgaard
Department of Biology, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark
The middle ears of birds are acoustically coupled through an air-filled interaural canal (IAC) often illustrated and modelled as a simple tube, which allows sound to propagate through the skull from one ear to the other and considerably enhance the cues for directional hearing. Theoretically, different combinations of frequency dependent gains and delays in the IAC can produce very different directionalities of the ears but it is still uncertain how interaural transmission gain and delay can be shaped by evolution by anatomical adaptations. A closer inspection of the zebra finch cranium using micro-CT scanning reveals that not only is IAC trabeculated and irregularly shaped but it also communicates with a set of highly complex, air-filled canals in the skull extending to the base of the beak. We tested the possible influence of these communicating cavities by measuring eardrum directionality and interaural transmission before and after filling the frontal cavities but found no dramatic effects. The question still remains what function these cavities serve and whether the ICA should be modelled as a simple tube.
Ole Næsbye Larsen, Rasmus Salomon, Kenneth Kragh Jensen, and Jakob Christensen-Dalsgaard
Department of Biology, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark
The middle ears of birds are acoustically coupled through an air-filled interaural canal (IAC) often illustrated and modelled as a simple tube, which allows sound to propagate through the skull from one ear to the other and considerably enhance the cues for directional hearing. Theoretically, different combinations of frequency dependent gains and delays in the IAC can produce very different directionalities of the ears but it is still uncertain how interaural transmission gain and delay can be shaped by evolution by anatomical adaptations. A closer inspection of the zebra finch cranium using micro-CT scanning reveals that not only is IAC trabeculated and irregularly shaped but it also communicates with a set of highly complex, air-filled canals in the skull extending to the base of the beak. We tested the possible influence of these communicating cavities by measuring eardrum directionality and interaural transmission before and after filling the frontal cavities but found no dramatic effects. The question still remains what function these cavities serve and whether the ICA should be modelled as a simple tube.
| Translated title of the contribution | Huleundersøgelser i zebrafinkehovedskaller: Hvad er den funktionelle interaurale kanal? |
|---|---|
| Original language | English |
| Publication date | 16. Jun 2014 |
| Number of pages | 1 |
| Publication status | Published - 16. Jun 2014 |
| Event | Internally Coupled Ears: Evolutionary Origins, Mechanisms, and Neuronal Processing from a Biomimetic Perspective - Institut for Advanced Study, Technische Universität München, Lichtenbergstr. 2 a, Garching, Germany Duration: 18. Jun 2014 → 20. Jun 2014 |
Conference
| Conference | Internally Coupled Ears |
|---|---|
| Location | Institut for Advanced Study, Technische Universität München, Lichtenbergstr. 2 a |
| Country/Territory | Germany |
| City | Garching |
| Period | 18/06/2014 → 20/06/2014 |