Noise ratings by car

BigglesPiP said:
I'm not confused at all; a rise of 3dB more means twice the amplitude of the sound in the air when you use one of these meters with a mic on it. It's a logarithmic scale.

dB being piped into a speaker electrically is a different measure, since dB can measure any alternating signal. This will not match the dB coming out of the speaker as noise.

One click on a standard radio is less than 1dB in the air.
Click to expand...
Well, at higher volumes you do get power compression where increased power into the speaker does not give increased volume, but below this level double the power (+3db volume increase) from the amp into a speaker will give a 3db increase in SPL.

That was not my original point however, my original point was that 1db is barely noticeable, so I dug out a link to prove this:

http://www.gcaudio.com/resources/howtos/loudness.html

Info is about halfway down.

Perceptions of Increases in Decibel Level
Imperceptible Change 1dB
Barely Perceptible Change 3dB
Clearly Noticeable Change 5dB
About Twice as Loud 10dB
About Four Times as Loud 20dB
Click to expand...
If you can find some information that says otherwise I'll be interested to know where it's from...

10dB sounds about twice as loud to humans, this is what I would call 'double the volume', but this depends on what scale you are using for volume. I prefer to use dB myself. With linear units (V or W), double the volume may well turn out to be 3db.
 
Last edited:
Jez said:
I have downloaded a level meter to my iphone, when the snow clears up i will be testing the levels in my (double glazed obv) S-Class which given that it is on 19's and RFT's, will be comparable to the double glazed E38 i would have thought :)
Click to expand...

That'll be interesting, cheers Jez. :)
 
I'm not quite sure what surface to test the car on, are those like to have been done on rubberised ultra quiet type tarmac do you think?
 
I guess its best case scenario, i'll test it on a normal but quietish stretch of the A34 when the snow clears up :)
 
R420LA6X2/4MNA said:
That'll be interesting, cheers Jez. :)
Click to expand...

Ok, did a few tests at 80mph. Only using "Sound level" on an iphone, so unsure how accurate, held up in the middle of the car rather than resting on anything etc.

Mercedes S-Class, 19" Rims with RFT's, but double glazed and air sprung - mid 60's.

Porsche 911 C4, 18" Rims, harsh suspension - low 90's.

Peugeot 206 1.4 - 16" Rims - Mid 70's.

Ford Focus 1.6 - 16" Rims - Mid 70's.

If anyone else can be bothered to do it it may be interesting. :)
 
Interesting, I'll grab an app and give this a go. Audi have claimed for the last few years the A8 is the quietest in its class so I'll post back later.

90dB seems high, especially compared to the last 2 cars.
 
Cheers, will be interesting :) Also post your rim combination as obviously the RFT's and 19's do not help matters with the S-Class compared with the 16" rims and balloons some models have.

Re the 90db, indeed, but i can quite believe it. The 911 isnt the most refined of vehicles on 18" rims and its very low profile tyres. Remember the other two run on balloons.
 
I got a ride in an 02 plate Mini Cooper yesterday. That was well noisy :eek:

And an uncomfortable and rough harsh ride.
 
Jonny69 said:
I got a ride in an 02 plate Mini Cooper yesterday. That was well noisy :eek:

And an uncomfortable and rough harsh ride.
Click to expand...

That is fairly typical of all sporty BMW products. The ride in M-Sport's while i wouldnt say uncomfortable at all, is quite rough and noisy compared with their non sporty counterparts.

Wish i still had the 530 Sport to test. Anyone with an iphone and an M-Sport please do. I'll guess low to mid 70's for them, and mid to low 60's for your A8, fett.
 
You must log in or register to reply here.
Back
Top Bottom