Do extant elephants have superior canal dehiscence syndrome?

Abstract

Conclusion: X-ray CT of an Asian elephant’s skull suggest that elephants do not have a labyrinthine 3^rd mobile window. This excludes the concept that elephants benefit from enhancement of bone conducted vibration by an extra opening of the labyrinth. This finding does not, however, exclude that elephants use bone conducted hearing for seismic detection, nor that other species may use an extra labyrinthine opening for improved detection of seismic signals. Objectives: In man, a pathologic extra opening of the bony labyrinth causes altered hearing with supranormal bone conduction. Theoretically, this variation in auditory performance could be advantageous for detection of seismic waves. Method: The skull of an adult Asian elephant was examined by X-ray computed tomography to investigate whether a natural ‘3^rd mobile window’ mechanism for enhanced sensitivity of body sounds exist in elephants. Results: Although the entire elephant’s skull was otherwise broadly aerated, the labyrinth areas were surrounded by dense bone.

Keywords:

• bone conduction
• conductive hyperacusis
• CT
• hearing
• seismic
• third mobile window

Acknowledgments

We are indebted to Peter Mortensen (NRM Stockholm) for securing the elephant skull for and during transport.

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.