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Sound Intensity

Sound intensity is measured in Decibels (dB). This is a logarithmic scale in which an increase of 10 dB gives an apparent doubling of loudness.

Sound pitch is measured in Hertz (Hz), the standard unit for the measurement for frequency. The audible range of sound for humans is typically from 20 Hz to 20,000 Hz, although, through ageing and exposure to loud sounds the upper limit will generally decrease.

How loud is too loud?

Continued exposure to noise above 85 dBA (adjusted decibels) over time will cause hearing loss. The volume (dBA) and the length of exposure to the sound will tell you how harmful the noise is.

In general, the louder the noise, the less time required before hearing loss will occur.

Environmental Noise Levels

According to the National Institute for Occupational Safety and Health, the maximum exposure time at 85 dBA is eight hours.

At 110 dBA, the maximum exposure time is one minute and 29 seconds. If you must be exposed to noise, it is recommended that you limit the exposure time and/or wear hearing protection.

A three dBA increase doubles the amount of noise, and halves the recommended amount of exposure time.

Sound Insulation

Two parameters are used to describe the sound insulation of a partition, Dw and Rw. Dw represents the sound insulation between rooms on-site. Since these figures describe the fnal site requirements, Dw levels are specified by clients and Building Regulations. Rw represents the lab tested sound insulation of an element making up a partition wall/floor type. Due to flanking and other factors, lab rated sound reduction levels will not be achieved on-site. Conventionally, there is a 5 to 10 dB reduction between a Rw lab tested figure and an on-site Dw figure. The conversion between Dw and Rw is relatively complex and takes into consideration receiver room volume, receiver room reverberation times and the area of the separating partition. The conversion between Rw and Dw should always be calculated.

E2 Specialist Consultants
July 9 at 11:10am
A domestic conversion in Fleet, Hampshire means a SAP conversion calculation is required to appease building control. One of our consultants is doing this and the EPC under approved document L1B.

E2 Consultants Delivering compliance solutions for Architects & Developers    Head Office E2 HOUSE, South Park Way, Wakefield 41 Business Park, WF2 0XJ    Questions? Call: 0800 043 8100

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