The time course of the Lombard effect has previously been quantified in stationary echolocating bats. However, echolocation calls during searching flight are coupled to the wingbeat cycle which makes the calls more energetically efficient. In contrast, the calls in the buzz phases right before target capture are completely decoupled from wingbeat cycle, and are weaker than other calls.
It is therefore hypothesized that bats during flight require the coupling to wingbeat cycle to be able to produce loud calls, and are therefore unable to compensate for noise during the buzz phases of echolocation.
In my master’s project, I seek to test this hypothesis and quantify the magnitude and timing of the Lombard effect in flying echolocating bats in the different phases of echolocation.