pantdino

I'm trying to get an idea of the db level people experience inside the car on grooved or rough concrete pavement like we have in So Cal.
I saw one article on a Cayman which said they got 75db on smooth asphalt at a racetrack and on rough concrete is was way louder
75db is pretty loud to begin with, so louder would be very loud

Anyone have an app on their phone who has measured it in their car?

Yes, I know I should test drive a car and measure it myself, but where the car is does not necessarily have the rough concrete I drive on.

I have SPLnFFT on my iPhone- it's great.

Jim

PapaC4S

The sound in the car will vary considerably based on the road, speed and tires. Poor worn summer sport tires will be much louder than new all-season tires. Asphalt is generally quieter than concrete although I have seen some loud asphalt jobs recently.

Sound level is typically measured in dBA which means it is weighted using the A scale for human sound perception.

I get about 70-72 dBA at 70 mph on asphalt and maybe 72-74 on concrete at 70 mph with all season tires. This is down considerably from the 76-80 dBA I was getting before I sound treated the car with a MLV/closed cell foam layer under the carpet and CLD tiles attached to all the panels. The car was very loud for my taste so I stripped the interior and did the treatment.

I use the Decibel X app on my phone.

pantdino

Yes, dBA scale. I hold my phone in my hand at chest level pointed forward. Where do you put your phone for the measurement? I find if it touching anything that transmits vibrations from the car the reading is (incorrectly) higher

Jim

Petza914

I'd worry about this in a Lincoln Navigator, not a sports car.

Nate R

I didn't know you can get a free dB meter from the App Store. I will check and report back. For science!

Bruce In Philly

2009 C2S 191K miles

I have a bit of experience with sound pressure meters... yea really... The first thing anyone will figure out is that the results vary WILDLY depending on where you hold or place the microphone and what "weighting" you select in the app. Yet another complexity is the frequency mix of the noise can vary human perception of loudness, and where you hold place the microphone can again, pick up a completely different spectrum mix. So..... if you use a meter, try different placements and pick one that anyone who reads your results can easily duplicate... including settings of your app. I believe Harry Metcalf (Harry's Garage) places his smart phone with some app at his side on the center console (on a towel?). In any case, he uses a consistent approach to placement so results are comparable... well sort of.

Just saying "I got 60 db at... " is useless.

Regarding cruising road noise in general... tires are pretty much everything over and above wind and engine. I will just throw this out there... Michelins are some of the quietest tires I have driven on... Pirellis the noisiest after say 50% tread life.

Peace
Bruce in Philly (now Atlanta)

ManoTexas

Put top down. Push PSE and sport chrono buttons. Run to red line. The decibel levels are glorious.

PapaC4S

I don't want much. I just want it all. I love it when I hit Sport Chrono and the PSE and hit the twisties in the mountains. Glorious sound.

I also want a quiet ride when I am going around town listening to some music. That's why I sound treated the car.

PapaC4S

To get a good sound reading, I use the averaging feature on Decibel X and hold the phone near my ear, moving from ear to ear. Any other position is not what you hear. I have found hat I get a pretty steady average after about 10-15 seconds of reading.

I have also used my calibrated UMIK microphone and the REW software on my PC. These readings are close to the ones on Decibel X on my phone. I use the PC and REW to EQ my stereo but it is pretty cumbersome to use on the road so the phone works fine.

pantdino

I think two people with the same app on the same type of phone held in the same way in the same position in their car will get numbers which can be compared, maybe +/- 5dB

PapaC4S

Just did a run out to Dulles Airport on the toll road from Tysons. It is a nice asphalt road with many newly paved sections. I got 67-68 dBA on the new sections and 69-70dBA on the older sections at 70 mph. Turning on the PSE added about 1-2 dBA. This is pretty good since my wife's Lexus gets about 65-66 dBA on the same road and speed.

Concrete definitely is louder. Was about 70-72 dBA on the few concrete sections that were pretty smooth. This concrete is not grooved .

This is a nice asphalt road. As I posted earlier, i typically see 70-72 dBA on a asphalt road.

carguy999

is this with the windows down and stereo at max volume?

Nate R

72 db here PS4s at 70 mph on the interstate. PSE on 72 db - exact same.

For kicks - got 111 dB out of my 50 watt guitar amp, before the wife put a quick stop to that. Second data point of 113 after she left for work.

gasongasoff

Wow +/- 5dB is horribly inaccurate to the point of being useless. 10dB is perceived as a DOUBLING of volume. And I bet most cars on the market fall within a +/- 5dB range.
Also, as Bruce alluded to, the frequency spectrum of those dB's matter. An SPL meter only measures the peak dB output after the filter is applied (most commonly A-weighting or C-weighting). This is important because humans perceive equal dB levels to be louder or softer depending on the frequency.

So, comparing notes on cabin noise using various smartphones and various apps with +/- 5dB accuracy without considering frequency spectrum is pointless.

PapaC4S

Yes there are a lot of variables in acoustics. I have taken graduate engineering acoustics classes and spent many years tuning sound systems and it drives me nuts sometimes to make sure I am working in a consistent manner to get good measurements.

So we can have a consistent discussion, I recommended the use of the dBA scale, a specific averaging measurement technique, and the measurement phone application. Also important to note is the speed, road conditions, and tire type. Others are free to comment but I get very consistent results with these techniques, maybe 1-2 dbA variation for a certain type of road at a certain speed..

I have spent a lot of time on sound reduction in my car so I don't have drone and tire noise and would love to hear other people's measurements and experiences. It would be preferred if they can relate specific measurement techniques and conditions rather than anecdotal statements. I hate tire noise and am pleased with the results I achieved and happy to share with the forum on how to make this happen.