“…In contrast, suitable acoustic methods (Figure 5) can record the sound arising from the arrival of even a single drop (Figure 6), and when rain is falling, the sound intensity of the multiple impacts can be related to the rainfall intensity in mm h −1 . Indeed, this effect is routinely considered by acoustic engineers in planning for the sound level inside buildings, especially those with metal roofing materials (Yan et al, 2016). In such contexts, there is a linear relationship between the sound level beneath the roof and the rainfall rate in mm h −1 , such that sound pressure data could in fact be used to estimate the rainfall intensity at roof level.Figure 5.The acoustic recording device (foreground) used by Dunkerley (2020) in the recording of rainfall.…”
Sound is produced by many geomorphic and hydrological processes, such as rockfalls and landslides, ocean waves, fluvial flood flows and collisions among moving bedload clasts. In these and other areas of study, acoustic methods have found useful application to detect and quantify the operation of important landscape processes. In some, such as the recording of river discharge, the occurrence of rare events such as exfoliation or the presence and movement of dust devils (willy-willies), the use of acoustic methods is still in a relatively early stage of development and testing. The use of acoustic methods in the recording of rainfall occurrence and intensity is also developing and has the capacity to yield data with higher temporal resolution than can be achieved using conventional rain gauges. Novel acoustic methods include the analysis of the sound recorded by security cameras, which potentially form a vast network of observing stations. The frequencies of sound generated by land-surface processes include audible sound, ultrasound and infrasound at frequencies below the human hearing range. All appear to provide opportunities for further development of useful research tools and methodologies.
“…In contrast, suitable acoustic methods (Figure 5) can record the sound arising from the arrival of even a single drop (Figure 6), and when rain is falling, the sound intensity of the multiple impacts can be related to the rainfall intensity in mm h −1 . Indeed, this effect is routinely considered by acoustic engineers in planning for the sound level inside buildings, especially those with metal roofing materials (Yan et al, 2016). In such contexts, there is a linear relationship between the sound level beneath the roof and the rainfall rate in mm h −1 , such that sound pressure data could in fact be used to estimate the rainfall intensity at roof level.Figure 5.The acoustic recording device (foreground) used by Dunkerley (2020) in the recording of rainfall.…”
Sound is produced by many geomorphic and hydrological processes, such as rockfalls and landslides, ocean waves, fluvial flood flows and collisions among moving bedload clasts. In these and other areas of study, acoustic methods have found useful application to detect and quantify the operation of important landscape processes. In some, such as the recording of river discharge, the occurrence of rare events such as exfoliation or the presence and movement of dust devils (willy-willies), the use of acoustic methods is still in a relatively early stage of development and testing. The use of acoustic methods in the recording of rainfall occurrence and intensity is also developing and has the capacity to yield data with higher temporal resolution than can be achieved using conventional rain gauges. Novel acoustic methods include the analysis of the sound recorded by security cameras, which potentially form a vast network of observing stations. The frequencies of sound generated by land-surface processes include audible sound, ultrasound and infrasound at frequencies below the human hearing range. All appear to provide opportunities for further development of useful research tools and methodologies.
“…O uso de coberturas metálicas em edificações comerciais e industriais apresentam um baixo desempenho acústico, pois esses sistemas são constituídos por elementos construtivos com pouca massa, quando comparado com sistemas de coberturas convencionais que, por apresentarem maior densidade superficial, possuem maior isolamento ao som [1,2]. Além disso, o ruído contínuo gerado a partir da vibração do conjunto de elementos que compõem os sistemas de coberturas, especialmente os sistemas de coberturas leves, podem amplificar os sons produzidos durante os eventos das chuvas [3].…”
Section: Introductionunclassified
“…Apesar do conhecimento desse princípio de propagação, a estimativa do comportamento energético pluvial é de difícil previsão dada a distribuição sazonal do tamanho das gotas e a dependência da velocidade de queda da chuva. [3,5,6] Um item importante para o conhecimento do ruído gerado é identificar a distribuição e tamanho das gotas, as quais se relacionam diretamente com o tipo de chuva e a altura de queda. Este ponto dificulta tanto a mensuração quanto processos de estimativas e de simulação em laboratório.…”
Section: Introductionunclassified
“…Este ponto dificulta tanto a mensuração quanto processos de estimativas e de simulação em laboratório. [3] Para as chuvas artificiais, a norma ISO 10140:2021 Parte 1, Anexo K, classifica as chuvas conforme sua intensidade, sendo uma chuva moderada a que apresenta uma vazão maior que 4 mm/h; a chuva intensa uma vazão maior que 15 mm/h; a chuva forte uma vazão maior que 40 mm/h; e a pancada de chuva uma vazão maior que 100 mm/h. De acordo com Hopkins et al [7] as medições em laboratório com chuva artificial podem ser usadas para comparar elementos individuais, mas não há uma relação estabelecida com a chuva natural, sendo a chuva artificial produzida nesses ensaios uma fonte padrão para definir o isolamento acústico.…”
Em estruturas de grandes vãos com telhas metálicas, o ruído da chuva pode ser amplificado resultando em prejuízos ao uso da edificação. Este trabalho busca determinar o desempenho acústico ao ruído de impacto de chuva em sistemas de coberturas com telhas metálicas, com 12 diferentes composições. Os ensaios foram realizados em laboratório conforme parâmetros da ISO 10140: partes 1, 3 e 5, com a geração de chuva artificial. Os resultados ponderados em A das amostras com telhas simples variaram de LiA 67,2dB a 74,2dB. Pode-se concluir que a instalação de camada intermediária com material fibroso reduz o ruído da chuva em até 22dB.
“…[4] and [5]). Yan, Lu and Li [14] conducted a detailed experimental investigation into the noise produced by both natural and artificial rain on a roof and noted that the wide range of natural rainfall rates and droplet sizes can result in significant variations in noise which are quite different to those simulated using the artificial rain specified in the ISO rainfall noise standard. They also presented empirical formulae for predicting rain noise due to natural rainfall.…”
This paper concerns the measurement and prediction of rainfall noise with a particular focus on measurements made using the method described in the ISO rainfall noise standard. Rainfall noise is generated by rain impacting on a surface which excites the surface producing noise. Here, several different models for the force produced by a water droplet impacting on a flat inclined surface are presented. These models are designed for the nominal intense and heavy raindrops described in the ISO standard and are validated against experimental measurements. The best-performed models have been incorporated into theoretical methods for predicting the noise produced by rainfall on a flat inclined panel. These methods are used to produce noise level predictions for heavy rainfall on a standard reference test specimen which are compared with experimental measurements and show moderate agreement. These experiments were conducted using the test method described in the ISO standard. Several issues which we encountered implementing this test method are described and a number of suggestions are made to improve this method. Finally, the theoretical models are used to investigate the effect of different parameters on rainfall noise for the purpose of illustrating potential sources of error during testing using the ISO standard method.1 Note that table K1 in Annex K of ref. [5] gives four rainfall type classifications (moderate, intense, heavy and cloudburst). These are attributed to IEC 60721-2-2. However, these classification names and the rainfall characteristics (rainfall rate, typical drop diameter and fall velocity) do not correspond with those given in the current version of IEC 60721-2-2 (published in 2012) which lists 'heavy rain' as having a rainfall rate of < 16 mm.h -1 and 'very heavy rain' as having a rainfall rate < 50 mm.h -1 . No characteristics, other than rain intensity are associated with the different rain classifications in IEC 60721-2-2. However, it is stated that rain, in general, has a droplet size distribution typically 1 mm to 2 mm in diameter, with diameters up to 5 mm to 8 mm in thunderstorms; fall velocities are stated as being typically between 2 m.s -1 and 12 m.s -1 .
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