In recent years, there have been discussions about airport noise monitoring systems and their ability to more accurately measure aircraft noise. Most of these systems are built to meet the type 1 requirements of ANSI S1.4-1983, Specification for Sound Level Meters. With advancements in microphone components and design, along with improved testing methods, the tolerances should be reviewed. Many airports use the measured noise data in support of noise mitigation programs and enforcement of noise abatement procedures. However, participation in some programs considers measured data more accurate than the microphone's tolerance. This could affect the spending of millions of dollars. Also, the noise abatement requirements at some airports invoke measurement accuracy to within 0.1 dB. These goals signal the need for new consideration. The microphone measurement error can be considered a combination of electronic, mechanical, and acoustic errors. The accuracy and linearity of electronic circuits is better than in the past and there have also been improvements in temperature, humidity, and static pressure effects. Field calibration devices and acoustic limitations must also be considered. Considering all of these factors, the system tolerances may deserve to be reduced.