2014 Engines: Do they sound right?

[rjsa]

If you are just to repeat your gospel you should follow your own advice. I'm trying to learn in the process here.

That is not the impression one gets from your post. You are not even addressing the points I made. Btw. I don't like to be quoted out of context. My remark about leaving it to Chris was based on the previous exchanges. Then you posted another comment that clearly did not consider the details already given and that prompted my remark. It would be appreciated if we can argue technically here.

That's exactly what I'm doing. Can't argue the analysys. Have doubts about the input data. But since my doubts would produce new analysys that woudn't meet your interests you will just discard them.

Chris asked me what I meant while you just called BS.

How can you dismiss the effects of frequency dampening into spectral analysys and claim you are arguing technically?

[rjsa]

Here's what I mean. Frequencies vary when onboard/on track recorded. Tunnel feeds back, recombines waves and kicks frequency to the sky. All this happening after the sound left the exhaust.

[youtube]http://www.youtube.com/watch?v=MQB_vKmPABg[/youtube]
Poor video, Il'l try to figure out how to push the audio into the screen cap.

[WhiteBlue]

Can't argue the analysys. Have doubts about the input data. ...How can you dismiss the effects of frequency dampening into spectral analysys and claim you are arguing technically?

Frequencies are not damped! You can clearly see that. The harmonics are all there. Amplitudes are damped but that wasn't the issue of this thread!

[rjsa]

Can't argue the analysys. Have doubts about the input data. ...How can you dismiss the effects of frequency dampening into spectral analysys and claim you are arguing technically?

Frequencies are not damped! You can clearly see that. The harmonics are all there. Amplitudes are damped but that wasn't the issue of this thread!

Semantics. Amplitudes dampened according to frequency.

The issue of this thread is the sound perceived by the expectator. That happens on track, with the expectator on the grand stands.

The discussion leaned this way when someone said that the single exhaust exit would result into the perception of highier pitched sound.

There is a theory saying that since the V8s have two pipes the expectator perceives only half the firing freqency.

An analysys was made comparing a V8 in the Dyno and a V6 in unknown conditions. The analysys showed both the V6 and the V8 having a very similar pitch even with the big difference in the firing frequencies.

I'm rasing the point that the engine pitch varies according to the way and the position it's being captured from.

This could result into the previous analysys being biased and in fact the difference in the sound pitch being indeed very big.

That's the issue of this thread.

[xxChrisxx]

The problem I've got rjsa is that you are mixing valid concerns with incorrect assumptions to draw conclusions that are not valid. So I'm not going to try to address all points in the thread, as it's spiraling into a bit of a mess as it is.

That's exactly what I'm doing. Can't argue the analysys. Have doubts about the input data.

Could be that the use of dyno recordings on your analysys filtered some of the highier frequency stuff and biased the results. Because from my reading of the graphs the difference of amplitude between 2nd and 4th on the V8 was pretty narrow.

This principle is a very valid point. In this case it's not justified, but we can explore the idea to show this. The phenomena you are describing, in that you hear something different to what is being produced, is very real. How we relate the two things is via a noise transfer function (NTF).
http://en.wikipedia.org/wiki/Transfer_function

H(s) = Y(s)/X(s)

Y(s) is the output sound - the thing we hear.
X(s) is the sound produced.

So the thing we hear = The sound output * the transfer function.

It's important to note that transfer functions will not affect frequency, it will affect amplitude and phase. This means the power spectral density will look different for the two.

Unfortunately with the tools at hand, there is no way to know (or find out) the NTF, to see exactly how sound is being altered by the environment between the source and the microphone is being altered. For showing order content, this is irrelevant, because you don't need to know the relative levels only that the order is present.

What you are asking is how do we know that the wall isn't blocking a load of 4th order power? The answer is, we don't. As I can't go and measure the NTFs, there is no way to conclusively prove that test cell walls will not mask sound in this fashion. From experience, that dyno run a fairly representative sound of the sound an engine makes.



So why does it sound different tackside?

You seem to be labouring under the assumption that the sound you hear in the grandstands is 'correct', and the on board shots are 'missing' something. In reality it's the other way round. The on board and dyno shots, and giving you are relatively unmolested sound. The grandstands are far enough away that you will hear both echos and reverberation. What you are hearing is essentially 'extra' sound. Not only that, but when you are sat in the grandstand the sound source is moving, and the sound will be subject to Doppler shift.

You are trying to attribute the sound difference to the engine, or how it's measured, when in fact the sound difference is an environmental effect.

Here's what I mean. Frequencies vary when onboard/on track recorded. Tunnel feeds back, recombines waves and kicks frequency to the sky. All this happening after the sound left the exhaust.

The track side footage shows higher frequencies because of the Doppler effect.



To finish:
The original argument was:

But unrealistic. It disregards that you hear only half the frequency of the V10 and V8s, because acoustically they have two separate banks using its own respective exhaust. The V6 will run with the full frequency because both banks run into the one turbo. Even the turbo V6 of the past had two separate banks with one turbo each. Their sound is also of lower frequency.

...is utterly absurd, but I didn't feel like starting an argument with you last night.

One does not "hear only half the frequency of the V10 and V8s, because acoustically they have two separate banks using [their] own respective exhaust," because - and this is vital - one hears the sound emitted from both exhausts!

The analysis clearly show WB to be right, and bhallg2k to be wrong. As the V8 plot contained half firing order, and the V6 didn't.


EDIT: Sorry this post isn't as comprehensive as the last one, it's a but rushed because this thread is moving too fast!

[xxChrisxx]

There is a theory saying that since the V8s have two pipes the expectator perceives only half the firing freqency.

An analysys was made comparing a V8 in the Dyno and a V6 in unknown conditions. The analysys showed both the V6 and the V8 having a very similar pitch even with the big difference in the firing frequencies.

Eh? They are operating at different engine speeds! Did you not understand this? Also it's not saying that they only perceive 'half the firing frequency'. It's saying they will hear this is the fundamental tone, the higher orders will give the sound it's character.

Also 530Hz and 666Hz aren't even remotely close.

[bhall]

[...]

The analysis clearly show WB to be right, and bhallg2k to be wrong. As the V8 plot contained half firing order, and the V6 didn't.

[...]

Really? If the assertion that "you hear only half the frequency of the V10 and V8s, because acoustically they have two separate banks using its own respective exhaust" is correct, why don't the results of the analysis look more like this?

[WhiteBlue]

The problem I've got rjsa is that you are mixing valid concerns with incorrect assumptions to draw conclusions that are not valid. ...It's important to note that transfer functions will not affect frequency, it will affect amplitude and phase. ...
Unfortunately with the tools at hand, there is no way to know (or find out) the NTF, to see exactly how sound is being altered by the environment between the source and the microphone is being altered. For showing order content, this is irrelevant, because you don't need to know the relative levels only that the order is present.

I hope this finally settles the questions you were still having about the initial analysis by Chris.

The original argument was:

But unrealistic. It disregards that you hear only half the frequency of the V10 and V8s, because acoustically they have two separate banks using its own respective exhaust. The V6 will run with the full frequency because both banks run into the one turbo. Even the turbo V6 of the past had two separate banks with one turbo each. Their sound is also of lower frequency.

...is utterly absurd, but I didn't feel like starting an argument with you last night.
One does not "hear only half the frequency of the V10 and V8s, because acoustically they have two separate banks using [their] own respective exhaust," because - and this is vital - one hears the sound emitted from both exhausts!

The analysis clearly show WB to be right, and bhallg2k to be wrong. As the V8 plot contained half firing order, and the V6 didn't.

Thank you, Chris. Nice to know that "utterly absurd" voiced by "bhallg2k" means nothing when investigated by a scientific mind. I'm constantly amazed by the arrogance of people who seem to have very little scientific understanding but tons of hubris and inclination to criticize other people who have more knowledge about the issue that is being discussed.

[bhall]

Why on earth would it look like that?

I have no idea!

I challenged the idea that "you hear only half the frequency of the V10 and V8s, because acoustically they have two separate banks using [their] own respective exhaust." I think your analysis has born this out, because it clearly shows that we do, in fact, hear the full frequency range of both engines, but, because of harmonic differences, the perceived pitch of the tones emitted are different.

[xxChrisxx]

Why on earth would it look like that?

I have no idea!

I challenged the idea that "you hear only half the frequency of the V10 and V8s, because acoustically they have two separate banks using [their] own respective exhaust." I think your analysis has born this out, because it clearly shows that we do, in fact, hear the full frequency range of both engines, but, because of harmonic differences, the perceived pitch of the tones emitted are different.

The claim was never that you don't hear 'half the frequency range'. As though one exhaust is emitting one frequency spectrum, and the other exhaust is emitting the other half.

It's that you hear a fundamental order, half that of firing frequency.

[rjsa]

The problem I've got rjsa is that you are mixing valid concerns with incorrect assumptions to draw conclusions that are not valid. So I'm not going to try to address all points in the thread, as it's spiraling into a bit of a mess as it is.

This principle is a very valid point. In this case it's not justified, but we can explore the idea to show this. The phenomena you are describing, in that you hear something different to what is being produced, is very real. How we relate the two things is via a noise transfer function (NTF).
http://en.wikipedia.org/wiki/Transfer_function

H(s) = Y(s)/X(s)

Y(s) is the output sound - the thing we hear.
X(s) is the sound produced.

So the thing we hear = The sound output * the transfer function.

It's important to note that transfer functions will not affect frequency, it will affect amplitude and phase. This means the power spectral density will look different for the two.

Unfortunately with the tools at hand, there is no way to know (or find out) the NTF, to see exactly how sound is being altered by the environment between the source and the microphone is being altered. For showing order content, this is irrelevant, because you don't need to know the relative levels only that the order is present.

What you are asking is how do we know that the wall isn't blocking a load of 4th order power? The answer is, we don't. As I can't go and measure the NTFs, there is no way to conclusively prove that test cell walls will not mask sound in this fashion. From experience, that dyno run a fairly representative sound of the sound an engine makes.

All fine, thanks for the lesson.

The track side footage shows higher frequencies because of the Doppler effect.

Not exactly, in many situations the car is moving away, so myself lacking better temrs would say the sound is red shifted.

So why does it sound different tackside?

You seem to be labouring under the assumption that the sound you hear in the grandstands is 'correct', and the on board shots are 'missing' something. In reality it's the other way round. The on board and dyno shots, and giving you are relatively unmolested sound. The grandstands are far enough away that you will hear both echos and reverberation. What you are hearing is essentially 'extra' sound. Not only that, but when you are sat in the grandstand the sound source is moving, and the sound will be subject to Doppler shift.

You are trying to attribute the sound difference to the engine, or how it's measured, when in fact the sound difference is an environmental effect.

Like discussing the sound of a trumpet trying to listen to it thru the metal horn wall instead of sitting in the theater.

To finish:
The original argument was:

But unrealistic. It disregards that you hear only half the frequency of the V10 and V8s, because acoustically they have two separate banks using its own respective exhaust. The V6 will run with the full frequency because both banks run into the one turbo. Even the turbo V6 of the past had two separate banks with one turbo each. Their sound is also of lower frequency.

...is utterly absurd, but I didn't feel like starting an argument with you last night.
One does not "hear only half the frequency of the V10 and V8s, because acoustically they have two separate banks using [their] own respective exhaust," because - and this is vital - one hears the sound emitted from both exhausts!

The analysis clearly show WB to be right, and bhallg2k to be wrong. As the V8 plot contained half firing order, and the V6 didn't.
EDIT: Sorry this post isn't as comprehensive as the last one, it's a but rushed because this thread is moving too fast!

Here I don't agree. You hear all the sound, you don't pick one side. And 200m away it makes no difference if the sound was mixed within or without the exhaust system.

[rjsa]

Why on earth would it look like that?

I have no idea!

I challenged the idea that "you hear only half the frequency of the V10 and V8s, because acoustically they have two separate banks using [their] own respective exhaust." I think your analysis has born this out, because it clearly shows that we do, in fact, hear the full frequency range of both engines, but, because of harmonic differences, the perceived pitch of the tones emitted are different.

The claim was never that you don't hear 'half the frequency range'. As though one exhaust is emitting one frequency spectrum, and the other exhaust is emitting the other half.

It's that you hear a fundamental order, half that of firing frequency.

Just read again WB's pearl you quoted: it is stating that you hear only half frequence. And he is constantly trying to use your analysys to justify that - in the best ppolitico spin doctor fashion possible: "You see, all is settled, Chris is telling you so, let's not discuss this any longer, lest you raise a valid point"

[xxChrisxx]

The track side footage shows higher frequencies because of the Doppler effect.

Not exactly, in many situations the car is moving away, so myself lacking better temrs would say the sound is red shifted.

In sound terms.
The NEEEEEEEEEEAA - is the frequency increasing.
OWWWWWWW- would be the frequency decreasing.

You can see this on the the recording trace you gave.
http://www.youtube.com/watch?v=MQB_vKmPABg

For the on board shots, you get a very constant sound level for a constant engine speed - which makes sense.
On the pass by you see the sound intensity increase and decrease at the higher frequencies.

Here I don't agrre. You hear ll the sound, you don't pick one side. And 200m away it makes no difference if the sound was mixed within or without the exhaust system.

Like discussing the sound of a trumpet trying to listen to it thru the metal horn wall instead of sitting in the theater.

This is again a sound source*transfer function thing. You are right your ears/microphone can't distinguish the difference. It only hears the end result.

You've got to remember, that the microphone was not recording one exhaust pipe. It was recording the sum of both, and still showed 2nd order.

[xxChrisxx]

Just read again WB's pearl you quoted: it is stating that you hear only half frequency. And he is constantly trying to use your analysys to justify that - in the best ppolitico spin doctor fashion possible: "You see, all is settled, Chris is telling you so, let's not discuss this any longer, lest you raise a valid point"

Well that's a good point, he does indeed say that. And if he did mean mean you only hear half the spectrum, it's 100% wrong. Though in context it's pretty clear hes talking about orders as he describes about where the exhaust pulses go.

I sometimes gloss over when people don't express themselves perfectly becusae the context allows me to understand what they are saying. It also leads to me sometimes assuming things, wrongly.

It's not really fair to crucify him because he wasn't careful with how he chose to express it.

I however am always careful

...Apart from when I am not.

[FW17]

Turbo I4 sounds ok!

[youtube]http://www.youtube.com/watch?v=4XPDNAk8MX8[/youtube]