Background noise, even at low levels, negatively affects concentration. Too much noise also elevates stress levels and blood pressure, and constant noise worsens symptoms rather than leading to habituation.
Emotional learning, planning, reasoning and willpower are all functions of the prefrontal cortex, an important feature of the brain's frontal lobe. Constant, low-level noise affects the body in much the same way as other stressors and triggers the release of the hormone cortisol. Under normal conditions, cortisol is vital in restoring stability in the body after a traumatic experience, but too much cortisol negatively impacts prefrontal cortex function. This means that disruptive background noise impairs the ability to make decisions, think clearly and regulate social behavior. The prefrontal cortex also plays a role in short-term memory, meaning that disruptive sound impacts learning and memory. Stress from sound might also decrease dopamine in the prefrontal cortex, which impacts higher brain function.
However, it is possible that not all noise is detrimental to concentration and brain function. Various studies find links between music, especially classical music, and improved spatial-temporal reasoning skills. Sometimes called the Mozart Effect, several experiments suggest that listening to classical music improves function in the regions of the brain that are most useful in math-related subjects.