Flexible vocal production control enables sound communication in both favorable and unfavorable conditions. The Lombard effect, which describes a rise in call amplitude with increasing ambient noise, is a widely exploited strategy by vertebrates to cope with interfering noise. In humans, the Lombard effect influences the lexical stress through differential amplitude modulation at a sub-call syllable level, which so far has not been documented in animals. Here, we bridge this knowledge gap with two species of Hipposideros bats, which produce echolocation calls consisting of two functionally wel...
