Tag Archives: noise

Noise and meteorological monitoring of a wind farm

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daga

Wind energy is one of the cleaner and more environmentally friendly of renewable energy, nevertheless the installation sites of Wind Farms (WF) must comply with different requirements (e.g. wind speed and direction, absence of obstacles, distances to dwelling). Mountain ridges and hills sites far from urban centre fulfil these requirements and were the firsts to be occupied by WF. However, the continuous increase of wind energy systems has implied that even more portions of territory were involved by the WF installation.

Moreover rather than their high level of environmental compatibility to others energy plants, a public resistance toward WF is frequently encountered. The motivations ascribed to the opposition are mainly connected to physical (noise and visual impact) and individual aspects (green energy or wildlife preservation attitude, degree of involvement in the project, economic benefits, NIMBY).

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The methodologies for noise assessment of WF at the receiver points are rather standardized and widely described by national legislations. Two methods are generally used. These methods assess the WF noise contribution from the measurements of the Combined Noise Level and of the Background Noise Level.

In the first method, the measurements must be carried out in two different temporal stages: when the wind turbines (WTs) are working and then, immediately after the time that the WTs are parked.

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In this way the background noise may be assessed, assuming that the measurements are recorded under the same weather conditions (remaining unchanged between these short time intervals). Subtracting the Background Noise Level from the Combined Noise Level it is possible to obtain the contribution of the WTs noise. Moreover some legislation recommend to measure the Background Noise Level “prior to site construction and operation” with a long-term measurement survey .

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Noise and meteorological monitoring of a wind farm

Realizzazione di un data base per le proprietà acustiche di materiali ecocompatibili

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database

Ai materiali ecocompatibili appartengono i prodotti di origine naturale (animale, vegetale o minerale) ovvero di non sintesi chimica che derivano da materiali rinnovabili, che non emettono sostanze inquinanti per l’ambiente e dannose per l’uomo, che sono riciclabili o biodegradabili e che richiedono un basso contenuto di energia per l’intero ciclo di vita.

I materiali ecocompatibili si stanno diffondendo nel settore dell’edilizia e sono impiegati anche per la correzione acustica di ambienti. Sul mercato sono disponibili diverse tipologie di materiali (kenaf, canapa, sughero, lana di pecora, ….).  Per ciascuna tipologia è stata dapprima svolta un’attenta analisi della diffusione sul mercato.

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Per ogni materiale individuato, sono state eseguite misure delle proprietà acustiche (coefficiente di assorbimento ad incidenza normale in un tubo ad impedenza e della resistenza al flusso dell’aria) in accordo con le vigenti norme UNI.

I risultati per ciascuna tipologia sono stati inseriti in un “data base” sia per esigenze di sintesi e consultazione, sia per semplificare la scelta da parte degli utenti. Il lavoro riporta le fasi di scelta del materiale, delle misure acustiche, della costruzione del “data base”; dell’inserimento delle informazioni “acustiche” nel “data base” e della relativa consultazione.

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Realizzazione di un data base per le proprietà acustiche di materiali ecocompatibili

Background Noise Effects on Noise Exposure Levels of PMP Users

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EUROREGIO1Listening to music in noisy environments brings to alarming habits of the personal music players (PMPs) use. A previous study showed that the subjective behaviour of users is to  raise the listening volume up to 12-14 dBA over the background noise.

Noise conditions largely influence the listening level but risks to hearing health can be really
assessed determining also the duration of the listening sessions. Standard earphones sealing causes noise annoyance from 75 dBA of the background noise level and listening volume and listening time should be related to this threshold of perception to keep the noise-induced health risk within safe values for a daily exposure.

EUROREGIO2

Within this study a group of PMP and supplied earphones were examined in laboratory to detect their maximum output volume level. The people listening behaviour from PMP usage was determined by means of laboratory tests and questionnaires. Exposing a group of  persons to quite and noisy conditions, during a listening session with PMPs and earphones, output volume levels were measured and noise exposure levels were computed.

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Background Noise Effects on Noise Exposure Levels of PMP Users