Journal of Exposure Science and Environmental Epidemiology ( IF 4.5 ) Pub Date : 2023-09-11 , DOI: 10.1038/s41370-023-00599-x Douglas J. Leaffer , Helen Suh , John L. Durant , Brian Tracey , Christopher Roof , David M. Gute
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Background
Environmental low frequency noise (LFN < 125 Hz), ubiquitous in urban areas, is an understudied area of exposure science and an overlooked threat to population health. Environmental noise has historically been measured and regulated by A-weighted decibel (dBA) metrics, which more heavily weight frequencies between 2000 and 5000 Hz. Limited research has been conducted to measure and characterize the LFN components of urban environmental noise.
Objectives
We characterized LFN noise at two urban sites in Greater Boston, Massachusetts (USA) using dBA and full spectrum noise measurements with aims to (1.) analyze spatio-temporal differences in the two datasets; (2.) compare and contrast LFN metrics with dBA noise metrics in the two sites; and (3.) assess meteorological covariate contributions to LFN in the dataset.
Methods
We measured A- and C-weighted, and flat, unweighted noise levels and 1/3-octave band continuously for 5 months using sound level meters sampling at f = 1 Hz and we recorded sound samples at 44.1 kHz. Our measurement sites were located in two urban, densely populated communities, burdened by close proximity to bus, rail, and aircraft routes.
Results
We found that (1.) LFN does not follow the same seasonal trends as A-weighted dBA loudness; there are spatial differences in LFN and its very low frequency noise components (VLFN) between two urban sites; (2.) VLFN and LFN are statistically significant drivers of LCeq (nearly independent of frequency) minus LAeq, (LCeq-LAeq) >10 dB, an accepted LFN metric; and (3.) LFN was minimally affected by high wind speeds at either Site.
Impact Statement
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Environmental low-frequency noise (LFN < 125 Hz), ubiquitous in urban areas, is an understudied area of exposure science and an overlooked risk to population health. We measured environmental noise across the full spectrum of frequencies continuously for five months at two urban sites located in Environmental Justice communities. We found that LFN did not follow the same seasonal trends as A-weighted (dBA) loudness, and we observed spatial differences in LFN and very low frequency noise (VLFN < 20 Hz) at the two sites. Not characterizing LFN and basing noise regulations only on A-weightings, a poor predictor of LFN, may expose populations to LFN levels of concern.
中文翻译：
城市环境低频噪声长期测量研究
背景
环境低频噪声（LFN < 125 Hz）在城市地区普遍存在，是暴露科学中尚未充分研究的领域，也是对人口健康的一个被忽视的威胁。环境噪声历来是通过 A 加权分贝 (dBA) 指标来测量和调节的，该指标更重视 2000 至 5000 Hz 之间的频率。在测量和表征城市环境噪声的 LFN 分量方面进行的研究有限。
目标
我们使用 dBA 和全频谱噪声测量来表征马萨诸塞州大波士顿两个城市地点的 LFN 噪声，目的是 (1.) 分析两个数据集中的时空差异；(2.) 将两个站点中的 LFN 指标与 dBA 噪声指标进行比较和对比；(3.) 评估气象协变量对数据集中 LFN 的贡献。
方法
我们使用声级计在f = 1 Hz采样，连续测量 A 和 C 加权、平坦、未加权噪声水平和 1/3 倍频程 5 个月， 并以 44.1 kHz 记录声音样本。我们的测量地点位于两个人口稠密的城市社区，距离公交车、铁路和飞机路线都很近。
结果
我们发现 (1.) LFN 并不遵循与 A 加权 dBA 响度相同的季节性趋势；两个城市站点之间的 LFN 及其甚低频噪声分量 (VLFN) 存在空间差异；(2.) VLFN 和 LFN 是 LCeq（几乎独立于频率）减去 LAeq 的统计显着驱动因素，(LCeq-LAeq) >10 dB，这是一种公认的 LFN 指标；(3.) LFN 在任一地点均受高风速影响最小。
影响报告
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环境低频噪声（LFN < 125 Hz）在城市地区普遍存在，是暴露科学中一个未被充分研究的领域，也是一个被忽视的对人口健康的风险。我们在环境正义社区的两个城市地点连续五个月测量了全频谱的环境噪声。我们发现 LFN 并未遵循与 A 加权 (dBA) 响度相同的季节性趋势，并且我们观察到两个地点 LFN 和极低频噪声 (VLFN < 20 Hz) 的空间差异。不描述 LFN 的特征并仅根据 A 权重制定噪声法规（LFN 的预测效果较差），可能会使人群面临 LFN 的关注水平。
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