Whistling is primarily controlled by the right side of the brain.

The human brain exhibits a phenomenon known as lateralization, where different functions are localized in specific hemispheres. While the left hemisphere is dominant for language and syntax in approximately 95% of right-handed individuals, the right hemisphere is typically responsible for prosody, melody, and pitch. This distinction was famously highlighted by researchers like Oliver Sacks and through clinical observations of Broca's aphasia.In patients who have suffered a stroke in the left middle cerebral artery, the ability to produce structured speech is often lost. However, because the right hemisphere remains intact, these patients can often whistle or sing lyrics they can no longer speak. This is because the neural networks for musical expression are physically separate from the Broca and Wernicke areas used for linguistic processing.Neurologists utilize this separation through Melodic Intonation Therapy (MIT), a technique developed in the 1970s by Robert Sparks and Martin Albert. MIT encourages patients to 'sing' or whistle phrases to bypass damaged left-hemisphere tissues. Over time, this therapy can even stimulate plastic changes in the brain, allowing the right hemisphere to take over some speech functions. This remarkable neuroplasticity demonstrates how the brain can reroute complex tasks through alternative musical pathways.