Research over the last few decades has documented a variety of adaptive vocal behaviors in echolocating bats
(Moss and Surlykke 2001; Hiryu et al. 2010; Goerlitz et al. 2010). Many of these adaptations can collectively be referred to
as a "jamming avoidance response" (a.k.a JAR), a term used to describe any combination of changes in the spectral or temporal
structure of the echolocation signal in response to external acoustic interference. Acoustic interference can arise from numerous
sources in the environment, including other nearby bats, defensive sounds of prey items, and anthropogenic noise.
My research is focused on determining the mechanisms of sonar jamming using both behavioral and neurophysiological methods. We recently determined that signals previously thought to jam bat sonar were ineffective in causing bats to miss prey items during foraging (Jones et al. 2018; Fig. 1), but that the signals did elicit echolocation changes that suggested the bats were increasing the signal-to-noise ratio of the returning echoes, one type of JAR.
Currently, I am working on a follow-up study that will investigate the effects of different interfering signal types on the prey-tracking behavior of echolocating bats. I plan to conduct playback experiments while simultaneously recording from neurons in the superior colliculus, a region of the brain that plays a role in both target selection and helps to control vocalizations based on feedback from prior vocalizations (Valentine and Moss 1997; Sinha and Moss 2007).
|Figure 1 | Recording setup for acoustic interference playback experiments.|
Goerlitz HR, ter Hofstede HM, Zeale MRK, Jones G, Holderied MW (2010) An aerial-hawking bat uses stealth echolocation to counter moth hearing. Curr Biol 20:1568 - 1572.
Hiryu S, Bates ME, Simmons J a, Riquimaroux H (2010) FM echolocating bats shift frequencies to avoid broadcast-echo ambiguity in clutter. Proc Natl Acad Sci U S A 107:7048 - 7053.
Jones TK, Wohlgemuth MJ, Conner WE (2018) Active acoustic interference elicits echolocation changes in heterospecific bats. The Journal of Experimental Biology. 221(15).
Moss CF, Surlykke A (2001) Auditory scene analysis by echolocation in bats. J Acoustic Soc Am 110:2207 - 2226.
Sinha, SR. Moss, CF (2007) Vocal premotor activity in the superior colliculus. Journal of Neuroscience 27(1): 98 - 110.
Valentine, DE. Moss, CF (1997) Spatially selective auditory responses in the superior colliculus of the echolocating bat. Journal of Neuroscience 17(5): 1720 - 1733.