Sound level in Car

[mirose]

I downloaded Decible Meter Pro for my Iphone (.99c but there are plenty of free versions too). I went for a drive.

I have a stroked 347 with shorty headers into Jpipes and the FFR SS side pipes. I have just over 300 miles on the car.

Normal acceleration (around town) up to 40 mph and the car in third gear around 2K rpm gets me averaging 80db with a peak of 92 during the actual acceleration.

Hard acceleration (not spiinning the wheels, but just about flooring it) from 0-50 or so on a bigger road away from people gotme up to 106 db during the acceleration.

The most interesting thing IMHO is that the average DB at 2K rpm or so was only about 80. I do plan to wear earplugs (and I do) but I find that unless I am driving it hard, I can carry on a conversation with my passenger (usually my 12 year old). I wonder if the shorty headers and j pipes are contributing to the somewhat quieter ride than I was expecting from what I had read before.

I also wonder if the FFR mufflers will blow out over time and get louder. My understanding is they have a fairly limited life.

Just curious if anyone has any comments. I don't really have a point here, just something to talk about a bit.

[SeanHM]

From what I understand, the pipes will get louder over time. One of the biggest threats to your hearing actually comes from wind noise.

[SeanHM]

Those readings are less than I expected though.

[Greg_M]

I were EP's all the time. I like to hear the birds singing when I stop for a view. Mine have 16K miles and they do seem louder than they used to. The wind and tire noise is bad at 70.

[MikeKelly]

Originally Posted by mirose

I also wonder if the FFR mufflers will blow out over time and get louder.

We cut a sidepipe apart at around 10,000 miles to work on sound for SCCA autocross.

The packing was nearly pristine.


So, I don't know how long it takes to blow them out.


HTH,

Mike

[SIZE-O]

Mirose,

Did you have something stuck inside you pipes to keep them that quiet

I had a friend of mine measure mine at 23" away from pipe outlet was 92 db and at 2500 rpm was 108 db.

Perry

[NiceGuyEddie]

very interesting, but i'm surprised it's not louder.

where did you hold the iPhone? in the car, or to your left ear?

i wonder how wind will affect db reading with an iPhone speaker.

as far as wind, i have found my car to be really quiet at 70mph. 80mph, everything magically changes, though.

what tires do you have? i heard soft tires like Nitto NT's make a world of a difference.

and don't forget, our ears are taking a wee of a pounding due to the vibration of the car.

i always wear earplugs.

[Bill Hughes]

Do you believe your IPHONE, and that cheap chinese microphone? Do you believe the app?

You need to calibrate against a referance SPL meter!

[2FAST4U]

Originally Posted by seanhm

from what i understand, the pipes will get louder over time. One of the biggest threats to your hearing actually comes from wind noise.

YES, THAT'S TRUE! DON'T ASK ME HOW I KNOw!

[G-Pete]

Originally Posted by Bill Hughes

Do you believe your IPHONE, and that cheap chinese microphone?

The Iphone is not made in China - It is made by TSMC in Taiwan, these guys are everything but cheap.

The level indicator is precise to 0.01 degree.
The camera has a better resolution than my Sony H50 ($450 new 3 years ago)

I do believe the dB meter app is pretty close to a $100 device.

[mirose]

Originally Posted by SIZE-O

Mirose,

Did you have something stuck inside you pipes to keep them that quiet

I had a friend of mine measure mine at 23" away from pipe outlet was 92 db and at 2500 rpm was 108 db.

Perry

I measured inside the car, by my face and I held it outside while driving too at arms length for goofs...no difference for the most part.

I think these cars are louder at the side (a person walking by the car) because the pipes are facing the side.

Originally Posted by NiceGuyEddie

very interesting, but i'm surprised it's not louder.

where did you hold the iPhone? in the car, or to your left ear?

i wonder how wind will affect db reading with an iPhone speaker.

as far as wind, i have found my car to be really quiet at 70mph. 80mph, everything magically changes, though.

what tires do you have? i heard soft tires like Nitto NT's make a world of a difference.

and don't forget, our ears are taking a wee of a pounding due to the vibration of the car.

i always wear earplugs.

I have Kumho Tires. No idea if those are "soft" or not.

I held the phone outside the car to see if the blast of wind would affect the DB and it didn't....

Well, this was not scientific, but still was interesting.

I'll say that the fact that I can carry on a conversation means it can't be much more than 80-85 db...

Finally, no one commented on the fact that I don't have straight headers/pipes. I have jpipes/shorties. I wonder if all that curving quiets things down a bit.

-M

[Olli]

Ignition timing, camshaft specification, cylinder heads (valve sizing) can all have an effect on the type and how harsh of a sound the engine makes. A mild to stock cam with stock to very mild heads can sound very different as compared to the same engine with a more radical cam and head package.

Olli

[Dan Babb]

I've read here from guys that switched from j-pipes to 4-into-4's that they are a lot louder. Don't remember seeing any DB readings though.

It makes sense that they would be because there are a lot less bends for the sound waves to bounce off of.

[Frank Messina]

Originally Posted by Olli

Ignition timing, camshaft specification, cylinder heads (valve sizing) can all have an effect on the type and how harsh of a sound the engine makes. A mild to stock cam with stock to very mild heads can sound very different as compared to the same engine with a more radical cam and head package.

Olli

Exactly right Olli. That's why listening to a muffler on somebody else's car and then buying and installing the same one on yours can be such a disappointment.

Frank

[BlitzAttack]

Originally Posted by 2FAST4U

YES, THAT'S TRUE! DON'T ASK ME HOW I KNOw!

You dont have to yell! We are not the ones who are deaf.

[NiceGuyEddie]

very surprised the iPhone reading didn't change with the wind.

even with my earplugs, if i put a bandana (or headband) over my ears it's MUCH quieter. so much quieter, i keep one in the car for a passenger, along with extra earplugs. so much quieter, i wear a headband or bandana as long as it's not too hot to do so.

my car is disturbingly quiet at cruise (75mph @1800rpm) and disturbingly loud with higher RPM's and hard driving.

protect your ears in any case... the $150 i spent on custom musician's earplugs were worth every penny. they have filters that let thru all frequencies. i also wear them to concerts and when doing woodworking.

can you please measure the noise level for us on the highway at about 70mph with the car in neutral?


cheers,

[CS14]

Hope I can add on some ideas in the thread... :-)

It is always difficult to measure the sound levels correct but I think all agree that two readings are interesting, in and outside the car.

A good way to measure the car's noise level is that someone measures the level when the car passing through the meter. I think the method we have to use in Sweden when we do the registering can be used.

First you drive in 2nd gear at 30 mph and when you pass through the meter you gives the full throttle, the distance to the meter should be 23 feet. Do the measurement in both directions, and then, you do the same thing in 3rd gear at the same speed. The four values you get gives a pretty accurate picture of how much it sounds when you are out driving and push it a little, which many of us do! :-)

Measuring the correct sound in the car is difficult, it also bee included so much wind noise, so what I see as interesting, is the sound included everything. Take your meter on a tour and see what it showed on average and peak and you probably have a good picture of the level.

Have fun and test the method and lets see what you have in dB!

[itsaw0rkinpr0gre$$]

I believe the iPhones with the new A5 chips have built in noise filters on the mic for ambient noise, if yes is it a good measureing device for true noise levels?

[Nemo]

New iPhone 5 has an A6 chip, and does have noise canceling.

But no matter what iPhone you use, unless you are using a calibrated SPL mic, the results are not going to be 100% accurate. The iPhones all have a "weight" applied to them, to compensate for their inherent shortcomings. (Biggest is the pinhole sized microphone)


Sent from my Autoguide iPhone app

[Mort]

This will be interesting. I just loaded a decible meter on my HTC android phone. Its reading about 42 dB in my cubicle. I will take this for a spin and see what i get in the roadster.

I have 4 into 4's and recently started wearing earplugs on longer rides. Recently i went for a 2 hour ride (1 hour each way with a hour break in-between) and on the way back i was thinking how the car seemed quieter and the ride was more enjoyable. Then when i got home my dog was barking and i noticed it seemed quieter. Then it hit me, i was getting deaf from that one ride!!! The next day my left eardrum hurt like i jammed something in my ear. Pretty sure i injured it.

So, dont take it lightly. I thought the "too much noise" complaints were BS until it happened to me.

[Finallygotit]

Originally Posted by 2fast4u

yes, that's true! Don't ask me how i know!

What?

[mctavish]

I put in the additional fiberglass and sink strainer fix in the sidepipes...it made a big difference in the higher frequency noise and left the lower frequency rumble/roar. Plus, with the T-5 trans in 5th gear, the RPMs drop quite a bit and all you really hear is some wind and tire noise. Very easy to carry on a conversation at 55-60 MPH.

[mirose]

Friday I have a 160 mile trip (weather permitting) in the roadster. I'll do some measurements on the highway etc.

As for the noise filter, etc. I have a funny feeling either 1) the app turns that off or 2) it compensates for that when it comes up with its DB number.

It seems to be pretty spot on compared to what the table is of real world comparasons....for example, it says a quiet home is 40 db and thats what its reading in my house

it ways 60 db is normal conversation...and thats around what I get when I am talking

etc etc etc.


So its pretty well calibrated...I'm sure its no perfect, but not too bad from what I can see....it seems very sensitive.

Michael

[NiceGuyEddie]

awesome. so hold it on the trans tunnel, and then lift it up. i wonder if it will pick up extra sound from the vibration.

i am still surprised the Db numbers are so low. even with my earplugs, my ears sometimes still ring a little after driving.

[mirose]

Looks like rain pretty much all day tomorrow...so I am not doing that trip. Maybe next week. I'll keep you posted after the trip.

As for ears ringing a bit after a long ride even with the ear plugs...I've noticed that too..I think a LOT of the sound is transmitted through the direct vibrations of the car. That isn't attenuated by the ear plugs. They only attenuate the sound that is traveling thorugh the air, into your ear canal.

There are some new headphones on the market that are marketed for runners that take advantage of this effect...the "speaker" (its not really an earphone since it doesn't go IN the ear) sits against the bone behind your ear and you hear the music thorugh bone-conduction of the sound, rather than air-conduction. The thinking is that you can hear the music, but also hear ambien tnoise like a car or a biker or whatnot and you are less likely to get hit while you are running.

So I bet this is part of the sound issue. I don't have any proof, but it seems about right.

Michael

[Mort]

Ok, went out and beat on the roadster a bit last night. I was seeeing Db readings in the low 80's at idle in the driveway, going down the road seemed to be in the mid 80's, and getting on it from a light pretty hard i saw high 80's to low 90's. That was with my son holding the phone in the middle of the cockpit about level with the rear view mirror.

Anyway, accurate or not, thats my result.

[Someday I Suppose]

I still remember pulling into the state inspection and the first thing the guy says is 'Why is this car so loud?'

I was so tempted to respond with 'What did you say?????'

When I built mine I was tempted to get some of the Zoomie inserts for the 4X4 headers, but my wife actually talked me out of it, she said the car is supposed to sound mean don't tone it down unless it gets to the point we are annoyed by it. That said on short trips I don't necessarily put in an earplug, but last year when we did the Coverd Bridge tour and spent most of the day in and around the car I did put one in my outter ear to quiet it down a bit.

-Scott

[JoeE]

My thoughts, the car is quieter in it than standing next to it. I find the wind noise to be the major contributor to hearing damage. From the AutoX racing perspective we need to be less than 88dB 25 or so yards away at a point of hard acceleration. I went with a UTC system so i am very quiet but, my ground clearance is just under 3".

Give someone your phone have them stand on the side of the road then drive by them in 2nd WOT and see what your reading is.