The instrument used to measure sound intensity is called a decibel meter or sound level meter. This device quantifies sound levels in decibels (dB), which is a logarithmic unit used to express ratios of sound pressure. It can assess ambient noise levels, evaluate sound exposure in workplaces, and measure audio in various environments, ensuring compliance with safety regulations. Sound level meters typically include features for capturing peak levels, average sound levels, and often possess frequency weighting options such as A-weighting, which adjusts the readings to reflect human hearing sensitivity.