Attenuation of northern dwellings to a linear source of noise

Abstract

Insertion loss in octave bands was measured for 14 residences in upstate New York using a carefully developed procedure similar to ASTM E336-71 A1.2. Although other dwelling attenuation data are available [e.g., House Noise-Reduction Measurements for Use in Studies of Aircraft Flyover Noise, Soc. Automative Engrs., AIR 1081; Oct. 1971] none was clearly applicable to rural areas of upstate New York and to sources of noise located near the ground. The source was simulated by a three-speaker array using broadband noise. Attenuation of transmission line noise was derived mathematically by applying the measured octave-band attenuations to a typical broadband transmission line noise spectrum and converting to A-weighted and sound levels. Average attenuation was about 15 dBA with windows open 2 ft2, and about 30 dBA with windows closed. [The study was conducted by Rochester Gas and Electric Corporation and their consultant Bolt Beranek and Newman in consultation with the New York State Departments of Public Service and Environmental Conservation.]

Highway noise criteria study :

“…Published outdoor-to-indoor isolation data obtained for aircraft noise sources are presented in Figs. 15 through 17, along with the average Noise Intrusion Reduction curve from the present study. For the purposes of this comparison, the average NIR values from the current study have been reduced by 1.5 dB to account for average spherical divergence differences between levels measured at the 3-m exterior microphone position and those at the building surface.…”

“…Omission of such terms is consistent with a measure of building sound isolation which combines the overall isolation due to the facade insulation and the attenuation within the receiving room. p A number of specific measures of building sound isolation have been reported in the literature [7][8][9][10][11][12][13][14][15][16][17][18][19] . Generally, these measure are defined so as to correspond to Eqs.…”

“…This occurs because reported noise reduction values correspond to the difference between the maximum exterior level and the maximum interior level regardless of when either occurred during the overflight [9,17,19]. In one recent study, the intent of the measurement was to assess the performance of dwellings in reducing noise from electrical transmission lines [15] . Due to the (spatially) linear nature of the source in this case, loudspeaker noise sources were placed outside the building in a line parallel to the building surface.…”

“…In many studies, the location of the interior microphone is not specified at all. In one recent study [15], two microphone positions were used, one at the geometric center of the room, and one at a typical listener location such as an armchair or near the head of a bed; however only the averages of these two interior levels are reported.…”

“…is the exterior sound pressure level at microphone position m and L, is the interior sound pressure level for the microphone at listener position n, This method of representing the average Noise Intrusion Reduction for each house was selected because the averaging represented in Eq. ( 4) corresponds to that specified in the ISO and proposed ASTM standards for sound insulation measurements [4,5] and also is the same as that used in a recent study of "dwelling attenuation" for purposes of assessing occupant exposure to exterior transmission line noise [15] From Eq. ( 4), NIR values averaged over the three interior listener positions were calculated and are presented in Appendices B, C, and D for each of the nine test houses and passby cases for which individual microphone data are reported.…”