[Rogue_fxdl]

I'm the new guy but been watching the f87 postings for some time. I'm gonna drive the hell out of the M2 when its here, turn the HK stereo up and hit the curves of the mountains roads every day for a ten minute drive to town. To the guy(s) who worry about the noise, go to lowes or home depot and get a case of the foam in a can, and "drill and fill" then duct tape the holes...lol As far as "sports car", M2 is insanely sporty and drifts with smoking tires and is a car.....jus sayin

[Verbiage]

Originally Posted by swagon

Yes, I have read that.

Ok grandpa.

[swagon]

Originally Posted by Verbiage

Ok grandpa.

[csbear]

Originally Posted by nikotine30

So, C&D measured the BMW M2's SPL@70 mpg as 72 db. For comparison:

- BMW M2: 72 db
- BMW 340i: 70 db
- MB E350 (2014): 68 db

(These figures are all from C&D's instrument tests.)

So, the M2 is "barely louder" than a 340i, and the 340 itself is "barely louder" than a luxo-barge E350. Based on this, it seems to be that we don't need to be too concerned that the M2 will be a loud car on the highway.

Damn, this means I have to get the M Perf Exhaust or Akra...

One thing I am a little worried about is that the M2 is not going to be loud enough. Even my brother's 991 GTS was not loud enough, hehe! The GT4 is a loud car when you get up there in the mid-range, with the PSE button on. And it sounds so beautiful in tunnels....

That's ok... I was't expecting it to be like the GT4 in the sound dept. But it will be fun doing a few mods to the M2.

Reminds me, I do want to hear a GT350R one day if possible. Another current car I really like from what I've seen...

[Verbiage]

Originally Posted by csbear

Damn, this means I have to get the M Perf Exhaust or Akra...

One thing I am a little worried about is that the M2 is not going to be loud enough. Even my brother's 991 GTS was not loud enough, hehe! The GT4 is a loud car when you get up there in the mid-range, with the PSE button on. And it sounds so beautiful in tunnels....

That's ok... I was't expecting it to be like the GT4 in the sound dept. But it will be fun doing a few mods to the M2.

Reminds me, I do want to hear a GT350R one day if possible. Another current car I really like from what I've seen...

Muffler delete.

[Adem1534]

Originally Posted by nikotine30

Guys, just to keep things in perspective, a 3 db difference in sound is classified as "barely perceptible". My stereo at home has a volume knob with decibels and I can say that I need to turn the knob at least a good 5-6 db for the sound to be clearly louder.

Technically, a sound that is 3 db louder than another sound has 2x more "energy" (amplitude), but because of the way our ears perceive sounds (psycho-acoustics), a doubling of the energy results in a sound that is perceived as barely louder:

- Imperceptible Change 1dB
- Barely Perceptible Change 3dB
- Clearly Noticeable Change 5dB
- About Twice as Loud 10dB

So, C&D measured the BMW M2's SPL@70 mpg as 72 db. For comparison:

- BMW M2: 72 db
- BMW 340i: 70 db
- MB E350 (2014): 68 db

(These figures are all from C&D's instrument tests.)

So, the M2 is "barely louder" than a 340i, and the 340 itself is "barely louder" than a luxo-barge E350. Based on this, it seems to be that we don't need to be too concerned that the M2 will be a loud car on the highway.

No, no, no. Let me clear this up. The decibal scale is logmarthmic, not linear.

72 decibals is approximately 58% louder than 70 decibals.

That's a lot!!!

[3tekcorps]

Originally Posted by Adem1534

No, no, no. Let me clear this up. The decibal scale is logmarthmic, not linear.

72 decibals is approximately 58% louder than 70 decibals.

That's a lot!!!

Exactly. The M235 was rated at 67 db. The M2 is 72. I thought the M235 was really comfortable on the highway, but the WRX was NOT. I guess I have to buy an M2 and an old 5 series now.

http://media.caranddriver.com/files/...35i-xdrive.pdf

[csbear]

Originally Posted by Adem1534

No, no, no. Let me clear this up. The decibal scale is logmarthmic, not linear.

72 decibals is approximately 58% louder than 70 decibals.

That's a lot!!!

Ah ha!! That makes more sense it is on a logarithmic scale. Thanks Adem1534!

[swagon]

Originally Posted by Artemis

M235i sound insulation:


M235i heat insulation:

For comparison, here's the M2.

SOUND INSULATION FRONT



SOUND INSULATION REAR



SOUND INSULATION ROOF (for vehicles without sunroof)

[3tekcorps]

That's a lot of missing parts.

Getting old sucks! In my 20s I gutted cats and mufflers with a crow bar. In my 30s I pulled out all the carpet and sound deadening material, but left the mufflers alone. Now I want the stock mufflers and the sound deadening material too!

[Verbiage]

Originally Posted by 3tekcorps

That's a lot of missing parts.

Getting old sucks! In my 20s I gutted cats and mufflers with a crow bar. In my 30s I pulled out all the carpet and sound deadening material, but left the mufflers alone. Now I want the stock mufflers and the sound deadening material too!

Damn grandpa!

[3tekcorps]

Originally Posted by Verbiage

Damn grandpa!

Shut up biznatch!

[Kantalias]

Originally Posted by Adem1534

No, no, no. Let me clear this up. The decibal scale is logmarthmic, not linear.

72 decibals is approximately 58% louder than 70 decibals.

That's a lot!!!

Actually, dB SPL = 20*log10(P/Po) so a doubling in sound pressure occurs every 6 dB, not every 3 dB. The reference power Po is 20 uPa. So...72 dB SPL is 25% louder than 70 dB SPL.

However, nikotine30 is absolutely right in his post about psycho-acoustics: it takes a 10 dB SPL increase for something to be perceived as twice as loud. Therefore, 72 dB SPL would be barely perceivable as being louder than 70 dB SPL.

The M2 is a loud car relative to most, but it's "all relative" as they say. The M2 is about the same at 70 MPH as an R8, a 1M, E9X M3, Mustang GT500, 370Z, or WRX; and the M2 is quieter than a Viper, Elise, GT-R, or 911 GTx.

[nikotine30]

Originally Posted by Adem1534

No, no, no. Let me clear this up. The decibal scale is logmarthmic, not linear.

72 decibals is approximately 58% louder than 70 decibals.

That's a lot!!!

Adem1534, thanks for your comments. The decibel scale is indeed measured on a logarithmic scale, and you are correct that a 2 db gain requires 58% more "energy".

What does "energy" mean? Suppose we are talking about sound reproduction. Suppose that you have a 100W amplifier that you turn up to the max, and you measure your speakers producing 90 db, which is quite loud. If you were a headbanger heavy metal type and wanted to play it even louder, you could think about upgrading to a more powerful amplifier. How much more powerful? Well, it turns out that you really need a MUCH more powerful amplifier to produce a significant increase in loudness.

This is a phenomenon well known in the audio world. You need increasingly more powerful and heavy amplifiers to produce only very modest gains in music loudness.

Compared to a 100W amplifier:
- A 200W amplifier will play only 3 db louder, which is "barely perceptibly louder"
- A 400W amplifier will play only 6 db louder, which is "clearly noticeably louder"


Now coming back to the car world (and to your example), while it's true that 72 db has more 58% more "energy" than 70 db, our ears simply don't perceive it that way. A 3 db increase is barely perceptible to the human ear. As Kantalis said, it takes a 10 db increase for our ears to perceive double the loudness.

For reference, see the chart below: 3 db is only about 23% louder to our ears, and 2 db would be maybe somewhere around 15%. We can conclude that a BMW M2 (72 db) is only about 15% louder than a BMW 340i (70 db) at a constant 70 MPH, which is really not a lot louder!

[nikotine30]

Originally Posted by csbear

Damn, this means I have to get the M Perf Exhaust or Akra...

One thing I am a little worried about is that the M2 is not going to be loud enough. Even my brother's 991 GTS was not loud enough, hehe! The GT4 is a loud car when you get up there in the mid-range, with the PSE button on. And it sounds so beautiful in tunnels....

That's ok... I was't expecting it to be like the GT4 in the sound dept. But it will be fun doing a few mods to the M2.

Reminds me, I do want to hear a GT350R one day if possible. Another current car I really like from what I've seen...

Csbear, for you and those like you who are hoping for a very loud experience in the M2, I think you can rejoice in the sound measurements of the M2 under acceleration. Although at a constant highway speed, it is not much louder than a typical luxury sports sedan, under acceleration I think we can expect to be significantly louder.

C&D measured the M2 at 89 db at "wide open throttle". For comparison, it measured the BMW 340i at 76 db, a difference of 13 db. From the world of acoustics we know that a sound which is 13 db louder than another is approximately 125% louder, or more than double the loudness!

C&D also measured your reference, the Cayman GT4 at 90 db, which is almost the same loudness as the M2 (89 db)

Speaking for myself, this suits me just fine because I prefer a car which is quiet for normal rides, but much louder when I want to have some fun.

[kovsky]

Originally Posted by nikotine30

... From the world of acoustics we know that a sound which is 13 db louder than another is approximately 125% louder, or more than double the loudness!

C&D also measured your reference, the Cayman GT4 at 90 db, which is almost the same loudness as the M2 (89 db)

Speaking for myself, this suits me just fine because I prefer a car which is quiet for normal rides, but much louder when I want to have some fun.

Exactly, the M2 is really checking all the boxes on my want-to-have list in a car. I can hardly believe I'll be driving mine in April.

[jtodd_fl]

Originally Posted by swagon

For comparison, here's the M2.

SOUND INSULATION FRONT



SOUND INSULATION REAR



SOUND INSULATION ROOF (for vehicles without sunroof)

This post makes me so happy. Thanks swagon

[jtodd_fl]

Originally Posted by nikotine30

Adem1534, thanks for your comments. The decibel scale is indeed measured on a logarithmic scale, and you are correct that a 2 db gain requires 58% more "energy".

What does "energy" mean? Suppose we are talking about sound reproduction. Suppose that you have a 100W amplifier that you turn up to the max, and you measure your speakers producing 90 db, which is quite loud. If you were a headbanger heavy metal type and wanted to play it even louder, you could think about upgrading to a more powerful amplifier. How much more powerful? Well, it turns out that you really need a MUCH more powerful amplifier to produce a significant increase in loudness.

This is a phenomenon well known in the audio world. You need increasingly more powerful and heavy amplifiers to produce only very modest gains in music loudness.

Compared to a 100W amplifier:
- A 200W amplifier will play only 3 db louder, which is "barely perceptibly louder"
- A 400W amplifier will play only 6 db louder, which is "clearly noticeably louder"


Now coming back to the car world (and to your example), while it's true that 72 db has more 58% more "energy" than 70 db, our ears simply don't perceive it that way. A 3 db increase is barely perceptible to the human ear. As Kantalis said, it takes a 10 db increase for our ears to perceive double the loudness.

For reference, see the chart below: 3 db is only about 23% louder to our ears, and 2 db would be maybe somewhere around 15%. We can conclude that a BMW M2 (72 db) is only about 15% louder than a BMW 340i (70 db) at a constant 70 MPH, which is really not a lot louder!

Please - your science is mucking up a great argument! If you could please stick to vague unprovable assertions and some overblown hyperbole, it would make this go much more smoothly.

[Verbiage]

Originally Posted by jtodd_fl

Please - your science is mucking up a great argument! If you could please stick to vague unprovable assertions and some overblown hyperbole, it would make this go much more smoothly.

omg shots fired.

[G8rGrl]

So, what's the bottom line? Is my prospective daily driver (M2) going to be a loud ass tin can that makes it impossible to take calls on the speakerphone? Or is it going to sound like a performance car that just happens to be a little louder than the M235i?

[csbear]

Originally Posted by nikotine30

C&D measured the M2 at 89 db at "wide open throttle". For comparison, it measured the BMW 340i at 76 db, a difference of 13 db. From the world of acoustics we know that a sound which is 13 db louder than another is approximately 125% louder, or more than double the loudness!

C&D also measured your reference, the Cayman GT4 at 90 db, which is almost the same loudness as the M2 (89 db)

Speaking for myself, this suits me just fine because I prefer a car which is quiet for normal rides, but much louder when I want to have some fun.

Thank you! I had totally missed that, and those decibel numbers look much better. And I agree on the last part as well, quiet when it needs to be and louder at open throttle is good for me as well.

The GT4 does have the engine right behind the ear, so that obviously is a big sound contributor as well.

[3tekcorps]

Originally Posted by G8rGrl

So, what's the bottom line? Is my prospective daily driver (M2) going to be a loud ass tin can that makes it impossible to take calls on the speakerphone? Or is it going to sound like a performance car that just happens to be a little louder than the M235i?

It's going to sound like a WRX at cruising speeds and a GTR at WOT!

There's a great solution though: