Noise pollution has become recognized as a potential danger to marine mammals in general, and to the St. Lawrence beluga (Delphinapterus leucas) in particular. One method to determine whether noise is having an effect on an animals auditory ability is to observe a natural and repeatable response of the auditory and vocal systems to varying noise levels. This can be accomplished by observing changes in animal vocalizations in response to auditory feedback. A response such as this observed in humans and some animals is known as the Lombard vocal response, which represents a reaction of the auditory system directly manifested by changes in vocalization level. This response is known in humans, songbirds, and some primates. In this research a population of belugas in the St. Lawrence River Estuary was tested to determine whether a vocalization‐as‐a‐function‐of‐noise phenomenon existed by using hidden Markhov classified vocalizations as targets for acoustical analyses. Correlation and regression analyses of signals and noise indicated that the phenomenon does exist and results of a human subjects experiment along with results from other animal species known to exhibit the response strongly implicate the Lombard vocal response in the St. Lawrence population of beluga.