Reako’s conditions and measurements:
*All conditions that differ from vwli are underlined/bold.
- Fit Sport
A/T with stock Bridgestone Turanza EL47Z at
34 psi
- PRM intake
-
Driver holding DB meter 2’ above e-brake lever- mic facing forward
-
Dry road – older 2 lane highway
- DB meter from Radio Shack:
Digital-Display Sound-Level Meter - RadioShack.com
- DB meter at A weighting (500-to-10,000 Hz)
Test Result #1 – Using “A” weighting:
35mph - 63 dbA
40mph - 65 dbA
55mph - 67 dbA
60mph - 69 dbA
Test Result #2 –
Using “C” weighting:
40mph – 85 dbC
60mph – 88 dbC
Trying to figure out why mine measured so quiet…
- My test highway (typical curvy 2-lane highway 55mph speed limit) may be smoother than yours.
- My engine (A/T) may turn fewer RPM than your M/T at 60mph.
- I did try to keep out of the throttle when measuring (PRM intake growl adds db’s)
- Maybe test yours again when the roads aren’t all wet?
Anyway, as 713_fit touched on a bit, the human ear may be more sensitive to specific frequencies which your sound deadening knocks down – meaning even though the overall db readings may not differ by a large margin, the frequencies that remain after sound deadening are not as bothersome/noticeable. Regardless, with the level of sound deadening you added, I would expect at least a 5 dbA drop across the board – this is likely the case, our readings are likely skewed by one of the endless environmental variables that may interfere with these type of tests.
Most importantly, this was fun! I can take some more measurements down the line, or perhaps try a different db meter some day. Let me know if you want to complete any more testing, and thanks for posting up your results! +1