The Lombard Effect in Tamarin Monkeys
Noise is a significant factor for animal communication. Consequently, many species possess adaptations that allow them to modify the acoustic characteristics of their vocalizations to compensate for noise interference. One adaptation common to many species of birds and mammals is a linear increase in vocalization amplitude with increasing noise, known as the Lombard effect. In humans, the magnitude of this relationship also depends on the amount of frequency overlap between the noise and the vocalization, and it is usually paired with simultaneous changes to vocalization frequency and duration.
We tested to see whether cotton-top tamarins, which also exhibit the Lombard effect, changed their call frequencies and durations in response to the bandwidth and/or level of white noise in their environment. We hoped to determine whether there was evidence for a link between the Lombard effect and other vocal noise compensation adaptations in tamarins, and to determine salient aspects of noise that may impact noise compensation in other species.