Signal lengthening is not a strategy for animals to mitigate noise interference

Many species of animals rely on acoustic communication for critical life activities. The efficacy of acoustic communication, however, can be seriously hindered by ambient noise. Although it has been widely reported that signallers modify the structure of their acoustic signals in noise, whether such signal modulations contribute to reducing noise interference is often unclear. Signal duration is a perceptually important parameter that can directly affect signal detection. Here, we address whether signal lengthening is an adaptive strategy for improving acoustic communication in noise, combing results from a meta-analysis, a noise playback experiment, and numerical simulations. The meta-analysis showed that animals from arthropods to mammals showed a mixed pattern of signal duration modifications in response to noise, covering all three possibilities of an increase, a decrease, and no change. The noise playback experiment revealed that noise-induced signal duration modulation was charact...