Open AccessEcholocating bats exhibit differential amplitude compensation for noise interference at a sub-call level
Author(s) -
Manman Lu,
Guimin Zhang,
Jinhong Luo
Publication year - 2020
Publication title -
journal of experimental biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.367
H-Index - 185
eISSN - 1477-9145
pISSN - 0022-0949
DOI - 10.1242/jeb.225284
Subject(s) - interference (communication) , acoustics , amplitude , noise (video) , compensation (psychology) , differential (mechanical device) , physics , computer science , telecommunications , psychology , optics , artificial intelligence , channel (broadcasting) , image (mathematics) , psychoanalysis , thermodynamics
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 Hipposideros bats which produce echolocation calls consisting of two functionally well-defined units: the constant-frequency (CF) and frequency-modulated (FM) components. We show that ambient noise induced a strong, but differential, Lombard effect in the CF and FM components of the echolocation calls. We further report that the differential amplitude compensation occurred only in the spectrally overlapping noise conditions, suggesting a functional role in releasing masking. Lastly, we show that both species of bats exhibited a robust Lombard effect in the spectrally non-overlapping noise conditions, which contrast sharply with the existing evidence. Our data highlight echolocating bats as a potential mammalian model for understanding vocal production control.