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Updated: Jul 18, 2026

Pupillometry to Assess Auditory Sensation in Guinea Pigs
Published on: January 6, 2023
Noise-induced vocal modulation in cotton-top tamarins (Saguinus oedipus)
S E Roian Egnor1, Marc D Hauser
1Department of Psychology, Harvard University, Cambridge, Massachusetts 02476, USA. egnor@fas.harvard.edu
Abstract:
The Lombard effect-an increase in vocalization amplitude in response to an increase in background noise-is observed in a wide variety of animals. We investigated this basic form of vocal control in the cotton-top tamarin (Saguinus oedipus) by measuring the amplitude of a contact call, the combination long call (CLC), while simultaneously varying the background noise level. All subjects showed a significant increase in call amplitude and syllable duration in response to an increase in background noise amplitude. Together with prior results, this study shows that tamarins have greater vocal control in the context of auditory feedback perturbation than previously suspected.
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