Acoustics: Measuring & calculating traffic levels outdoors vs indoors

Interested if anyone has measured the noise (db) levels of properties near main road traffic and suspected of being on the boderline of tolerable, and the views of anyone with a bit of an interest in acoustics.

Have a property in my sights which is near a main road (approx 3-4 lots back from it, 50-70m approx). The building has a narrow direct line of sight and is on the 3rd storey. I was able to measure a fairly constant 45db on the ground floor of the property outside the garage, with the occasional spike up to 58db.

I wasn't able to measure the levels while inspecting the property. Was wondering if anyone knows the reduction I could expect from:

a. being indoors with the windows open (not fully, enough for air)
b. being indoors with the windows closed
c. being indoors with some sort of decent double glazing.

The recommended level for indoors for sleep is something like 30db, not sure I can get the place anywhere near that...

The property is otherwise a good buy, but I realise this could be a bit of gamble, or potentially I am being overly cautious (light sleeper...).

 

An acoustic consultant is best to give advice. The noise level will vary with sound level, frequency, duration and time of day. Factors such as hills and declines with truck traffic can radically alter noise levels. The RMS often love solid walls to use as a noise barrier but this can attenuate noise down long hard surfaces on three sides so noise that is distant can be a local concern.

The specific building will play a major element in that. Most poorly constructed dwellings wont reduce noise as well as a well designed and situated dwelling. The materials, distances and their quality will play a important part. Glazing can be a waste of $$ if the walls are fibro or cladding for example or there is a poor quality roof and ceiling.

A sensitive person will find noise very much a nuisance at even a low level versus a quiet property away from noise. This is why property near main roads can pose a problem at sale. Noise levels are a complex mathematical issue and can mislead about the intensity. A 0db nighttime noise level is a obvious practical personal target.

 

Thanks Paul - thank you for taking the time to reply and giving some great info.

 

Hi Howler

Fellow light sleeper here and I do noise assessments for work. This may be too late for the property you were looking at but maybe will help in the future.

a. a 5 dB reduction could generally be expected through open/partially open windows

b. dependent on the window type but conservatively should provide around at least 10 to 15 dB.

c. double glazing should provide north of 35 dB but as Paul mentioned this may be compromised by poor building components/ construction elsewhere. But windows usually are the weakest components of buildings and things like acoustic sealed frames and laminated glass may be appropriate alternatives to heavy double glazing for noticeable improvement.

You're right re the recommended level being 30dB(A) for inside sleeping areas for a constant type of noise. It's difficult to say if 30 dB(A) is ok for you and noise disturbance is highly subjective. Also whether the road carries light vehicles only versus trucks should be considered. Engine braking noise, trucks accelerating from traffic lights would be bad news for a light sleeper.

Out of interest, what did you use to measure noise levels?