Noise walls were built in locations that warranted noise mitigation in compliance with state and federal regulations based on noise modeling completed prior to construction. ADOT will continue to measure noise levels along the entire freeway corridor to evaluate impacts and ensure that noise levels remain at or below what is permitted by state and federal regulations. ADOT’s policy is to reduce the impact of freeway noise on adjacent homes, schools and churches by building sound walls or berms. Based on the noise modeling included in the Environmental Impact Statement, building sound walls ranging in heights from 16 to 20 feet adjacent to the residential communities would minimize the noise impacts of the freeway traffic and meet ADOT’s threshold of 64 decibels which is lower than the federal regulations (67 decibels). As a comparison, conversational speech is typically measured at 60 decibels.