SOUND LEVEL MAPS

This portion of the report contains interactive and static, downloadable maps of sound levels, based off of sound data collected during a year-long monitoring campaign. We measured sound at 400 sites around the City of Boston, at various times of day and various days of week. The maps found within this section of the report are based on three different sound metrics:

• A-weighted decibel (dBA): This metric is most typically used when monitoring and describing environmental sound. The A-weighted decibel discounts both lower and higher frequencies as the ear is less sensitive to these frequencies. We map the dBA during the daytime and nighttime for both the weekday and weekend.

• The Un-weighted decibel (dB): This metric describes the true sound level. The un-weighted decibel does not penalize any of the frequencies and makes no assumptions about what the human ear can perceive. We map the unweighted dB during the daytime and nighttime for both the weekday and weekend.

• The difference between Un-weighted and A-weighted sound: This metric describes what the A-weighted sound level casts off. We theorize that in areas where the difference is greater may include areas with higher levels of either low or high frequency based sound. We this difference during the daytime and nighttime for both the weekday and weekend.