The board of directors of a condominium association in Lisle, Illinois, wanted to obtain a acoustical professional’s opinion regarding acceptable and non-acceptable residential noise levels. An acoustical assessment and noise survey were conducted.
Based on the results of the survey, an analysis of noise criteria, appropriate acceptable noise levels, and noise guidelines, a soundproofing recommendations was developed and provided. NC (Noise Criteria) Curves 25 to 40 which correspond to equivalent sound level of 35 to 48 dB(A) were recommended for the residents.
The HVAC (heating, ventilation, and air conditioning) noise was one of the dominant noise sources in the condominium. As shown in the figure, the noise spectrum of HVAC noise is just at and below NC Curve 40. The ambient noise is well below NC Curve 25. Overall, the noise levels measured at the condominium units are below NC Curve 40, 48 dB(A).
NC Curves 25 – 40 vs ambient and HVAC noise (Band 4 = 500 Hz)
The following responses were noted during interviews with the residents:
The objective of this project was to determine appropriate noise levels for the 851 unit condominium’s residents. A noise survey, interview, and analysis were conducted to determine the noise criteria, noise sources, and appropriate acceptable noise levels. Based on the results of the survey and analysis, a soundproofing recommendation was provided.
Residents are responsible to ensure that sound pressure levels in each condominium unit do not exceed 48 dB(A). Specific noise levels are summarized below.
Day time is defined as the time period from 7:00 am to 9:00 pm (Saturdays and Sundays, 8:00 am to 10:00 pm). The acceptable noise level at those times are 48 dB(A) or below. If the ambient noise level is greater than 48 dB(A), then the applicable limitation is 10 dB(A) above the ambient noise level. This allows for a higher noise limit to account for uncontrollable activities such as construction noise, power equipment, etc.
Night time is defined as the time period from 9:00 pm to 7:00 am (Saturdays and Sundays, 10:00 pm to 8:00 am). The acceptable noise level at those times are 48 dB(A) or below.
Residents are responsible to ensure that all measures regarding soundproofing the individual condominium units are taken. Measures may include providing adequate soundproofing and vibration isolation for noise sources such as HVAC noise, plumbing, and noise from appliances. Owners and residents are also responsible for activities inside units such as listening to music, watching TV, conversations, kitchen activities, house-keeping activities, and pet noise.
The board of directors of the condominium association and residents have implemented and enforced the noise guidance as recommended.