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Discussion Starter · #1 ·
I downloaded a Decibel meter app. for my Droid X2 a few weeks ago to measure the sound levels at work.

Today, on my drive home, I got curious of how loud it is inside my X. Started the app., rolled up the windows, and kept my speed at 45. No stereo, no A/C, no talking, just the sound of my X humming down the road.

For those of you who have a smartphone of some kind, and those who want yet another (almost)useless app., download a Decibel meter app. and find out how loud your X is!

At 45mph, with the windows rolled up, the stereo and A/C turned off, on an average-quality road (not recently paved, but not rough or bumpy) I got a reading of 68db.

How about you?
 

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Windows up, air off, radio off, no talking mine idles at 55. Held it up the the exhaust and it jumped to 72. I'll have to see what it's at going down the road
 

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With my AC on and my music up to what I listen it was at 80. Then with everything off again running at 45mph it was 63
 

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Discussion Starter · #5 ·
Originally posted by AaronsX:"With my AC on and my music up to what I listen it was at 80. Then with everything off again running at 45mph it was 63 "
I put my stereo to where I usually listen to it, and while playing Beastie Boys - The New Style, it peaked at 74db...which just means I need to upgrade my speakers. This was with the windows up, but no A/C. I was trying to capture/concentrate the sound, haha.

Interested to see the range of responses from this. I know it relates heavily to the tires you're running, but I'm curious of just how much noise one particular tire makes compared to another.
 

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Not to burst the bubble on the concept of the thread but that thing is way to inaccurate cause majority of factory sound systems peak at over 100db but cool idea though
 

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A phone isn't going to be a reliable dB meter....not to burst bubbles but no matter how smart your phone is with a crappy microphone and one that small the measurements won't be accurate. dB's are not like a regular unit of measurement they are the relationship of two measurements of power (which have greatly different magnitudes).
so if the first value is 23 and the second is 4.7 trillion, then you'd say it is 113 dB's greater.
Standard dB equation is dB= 10 log (power A/ power B). So every 10 decibels increases by a greater number.

The usefulness of all this becomes becomes apparent when we think about how the ear perceives loudness. First of all, the ear is very sensitive. The softest audible sound has a power of about 0.000000000001 watt/sq. meter and the threshold of pain is around 1 watt/sq. meter, giving a total range of 120dB. In the second place, our judgment of relative levels of loudness is somewhat logarithmic. If a sound has 10 times the power of a reference (10dB) we hear it as twice as loud. If we merely double the power (3dB), the difference will be just noticeable.

[The calculations for the dB relationships I just gave go like this; for a 10 to one relationship, the log of 10 is 1, and ten times 1 is 10. For the 2 to one relationship, the log of 2 is 0.3, and 10 times that is 3. Incidentally, if the ratio goes the other way, with the measured value less than the reference, we get a negative dB value, because the log of 1/10 is -1.]

I don't know what app you're using, but I doubt that even if it uses the log functions it can read it accurately with that tiny little cheapo mic that phone companies use.

Hope this helps :].....I could talk about this shit all day

....to answer the thread mine is always loud lol

Edit: The frequencies a human ear can hear range from 30Hz to 22-24,000Hz. You're phones cheap mic can't hear all of these frequencies so it cancels them out, which means the dB is off. I'm not sure how much, but it might be significant.
 

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Yeah I don't think I'd want to know the true dBs inside my X with the music where I listen to it.
 

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F*** who even really wants to screw with log rythyms to find out? lol
 

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What I listen to at the volume I choose it's loud don't care what the DB level is

 

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At 65 windows up all that bull.. was arounf 82-84 with a max of 86. True representation? Idk but I like it
 

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Discussion Starter · #14 ·
Thanks for all the input guys!

I wasn't really looking for/wondering about stereo noise though...just road noise. I know I've seen people asking about how loud certain tires are, how much louder an X would be after removing the headliner/carpet, stuff like that. I figure this way, we could get a collaborative baseline figure of road noise volume; especially since so many of us run different tires at different sizes. (In case anybody is really that concerned with how loud one particular tire is over another).

Weerez935, thanks for droppin' that knowledge of how dB levels are calculated and all that technical jargon. I know a Droid app. isn't the most accurate dB meter (haha), but I figure it's "good enough" for the type of info I was looking to gather.
 

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im gonna love this thread. the subwoofer i have should hit between 146-149db if done right. goal of the xterra is the break the windshield with bass (150+db)

edit: i have a build thread about it but im still waiting to build the box. should happen next weekend if everything goes according to plan
 

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I just know that everyone that rides in mine at some point will say, "I can't believe how quiet it rides". That is, until it rains and then the rear passengers are yelling 'WHAT? WHAT?' all the time. Damn those rear inner fender wells are noisy in the rain.
 
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