Ways you have found to get xtra bass...

[audioholic 5,000+ posts]

What in the hell are you talking about.
Agian. Sound is only strictly ambient pressure variations in enclosed rooms too small for an actual wave to exist.

I'm not talking about what one point is experenceing....because all sound is is ambient pressure variations...I'm talking about the rooms as a whole. If you open a window you give the pressure a place to exit and an actual wave is formed.

Try this. Stick the meter in the kick and do a burp sealed up, open the door and do a burp same frequincy and power level. 9/10 times you will gain.

What am I talking about? What the "hell" are YOU talking about?Our ears read sound as pressure changes, in an enclosed room or otherwise.

"Try this. Stick the meter in the kick and do a burp sealed up, open the door and do a burp same frequincy and power level. 9/10 times you will gain." - And this proves its not a bandpass situation? No it doesn't. It proves its louder with the window down, something I did not contest.

I dont know what your problem is, but I stated whats considered to be the most widely accepted theory/reason behind louder bass with the windows down (bandpass situation) and you come at me like I have no clue what Im talking about. Whatever. Want to get into a debate over particle velocity, quote Richard Clark and all that, just to show we both are not idiots here? I dont, Im not insecure in my knowledge of the subject, not even after your attempts to belittle me. Im not going to argue with you over this topic, just to argue.

 

[luvinthebass 5,000+ posts]

You have an interesting theory. But then, by your theory, once we travel further from the sound source than its corresponding wavelength, the sound would disappear. As this is obviously not true....

the sound doesn't dissapear it just get quieter as it travels and loses 6 decibals a meter, like bass, a note would hit the first sound wave and push it even farther the next, that's why you can hear bass in the distance sometimes.

 

[audioholic 5,000+ posts]

the sound doesn't dissapear it just get quieter as it travels and loses 6 decibals a meter, like bass, a note would hit the first sound wave and push it even farther the next, that's why you can hear bass in the distance sometimes.

Close, but not quite. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

"2.9 How does sound decay with distance?

At distances large compared to the size of the source, sound intensity diminishes according to the inverse square law.

I = Io/D^2

This is relatively simple to reliably calculate, provided the source is small and outdoors where no echoes occur. (But indoor calculations in a reverberant field are rather more complex. )

If the noise source is outdoors and its dimensions are small compared with the distance to the monitoring position (ideally a point source), then as the sound energy is radiated it will spread over an area which is proportional to the square of the distance. This is an 'inverse square law' where the sound level will decline by 6dB for each doubling of distance.

Line noise sources such as a long line of moving traffic will radiate noise in cylindrical pattern, so that the area covered by the sound energy spread is directly proportional to the distance and the sound will decline by 3dB per doubling of distance.

Close to a source (the near field) the change in SPL will not follow the above laws because the spread of energy is less, and smaller changes of sound level with distance should be expected.

If the observation position very close to the source, at a distance that is small compared to the size of the source, the sound level changes very little with location in that source area. One may be able to determine the "virtual center" of the whole sound field, whence inverse square law calculations can proceed in reference to that distance, for locations outside the source area.

The surrounding environment, especially close to the ground, and in the presence of wind & vertical temperature gradients, has a great effect on the sound received at a distant location. Ground reflection affects sound levels more than a few feet away (distances greater than the height of the sound source or the receiver above the ground). Wind and air temperature gradients affect all sound propagation beyond 100 meters over the surface of the earth. Sound propages well downwind (traveling with the wind), and very lirrle upwind. When the ground surface is cooler than the air just above it ("inversion"), typically late at night and just before dawn, sound will travel great ditances across the landscape even without any wind.

In addition it is always necessary to take into account attenuation due to the absorption of sound by the air, which may be substantial at higher frequencies. For ultrasound, air absorption may well be the dominant factor in the reduction.

*** 2.10 What is the sound power level?

(See ACCULAB Reference Sound Source on this site:

http://www.campanellaacoustics.com/rssman.htm )

Sound power level, Lw, is often quoted on machinery to indicate the total sound energy radiated per second. It is quoted in decibels with respect to the reference power level. The reference level is 1pico-watt (pW) [1x10^(-12) watts]. One watt of radiated sound power is represented as "Lw=120 dB re one picowatt". If the reported sound power is in terms of A-Weighted spectral weighting, a suffix, A, is applied to form dB(A).

The sound pressure level (SPL) resulting from sound power (Lw) being radiated into free space, e.g. over a paved surface, is computed from

SPL = Lw - 20*log® - 11 dB re 20 uPa (R in meters)SPL = Lw - 20*log® - 0.7 dB re 20 uPa (r in feet)

If instead the sound is emitted over a reflecting plane such as a hard surface, three (3) decibels are added to the SPL.

For example, a lawn mower with sound power level 100 dB(A) will produce at a sound pressure level (SPL) of about 89dB(A) at the operator (you) position over grass and 92 dB(A) when the mower is operated over a hard surface such as your driveway. At your neighbor's yard 50 feet (15m) away, the SPL will be is 65 dBA." - http://www.campanellaacoustics.com/faq.htm#basic_decay

 

[Relax 10+ year member]

AudioHolic is right- rolling down windows often makes your car louder by making your sealed or ported box a much larger 4th or 6th order (respectively). Its not because the pressure can escape. In fact- that would be without a doubt the opposite of what you want. SPL is a measure of pressure created by sound, if the pressure is allowed to escape, you loose dBs.

Look up on google how scientist recreate extremely loud SPLs- its not by building rooms with holes or by placing the speaker in the middle of a field so pressure can escape.

 

[samson 10+ year member]

AudioHolic is right- rolling down windows often makes your car louder.

You guys are making me paranoid. I'll no longer be able to roll the windows down BEFORE I fart. lol! //content.invisioncic.com/y282845/emoticons/tongue.gif.6130eb82179565f6db8d26d6001dcd24.gif

 

[snoopdan 5,000+ posts]

Want to get into a debate over particle velocity, quote Richard Clark and all that.

you can always tell when someone thinks they have the upper hand when they pull the "richard clark card" //content.invisioncic.com/y282845/emoticons/laugh.gif.48439b2acf2cfca21620f01e7f77d1e4.gif

 

[smd4life 5,000+ posts]

AudioHolic is right- rolling down windows often makes your car louder by making your sealed or ported box a much larger 4th or 6th order (respectively). Its not because the pressure can escape. In fact- that would be without a doubt the opposite of what you want. SPL is a measure of pressure created by sound, if the pressure is allowed to escape, you loose dBs.
Look up on google how scientist recreate extremely loud SPLs- its not by building rooms with holes or by placing the speaker in the middle of a field so pressure can escape.

i said that while ago..

 

[CBFryman2 5,000+ posts]

I know this is true with many systems, but its not the norm.

That's the problem.

The norm would be most systems/vehicles. With most systems venting the cabbin gains SPL, not only to the ear but also on the sensor in most common placements (Headrest, Dash, Kick). There in your statement is false and that is exactly what I was disproving.

//content.invisioncic.com/y282845/emoticons/fyi.gif.9f1f679348da7204ce960cfc74bca8e0.gif any time you vent the cabbin with out have the system completely open you are essentially creating a bandpass enclosure.

According to you, putting a sensor in a bandpass box then plugging the port will be louder than unplugging the port with the sensor in the box. I'm sure we can agree that isnt true.

Now we can go look up exactly how and why a bandpass box works.

kthxbi.

 

[Relax 10+ year member]

That's the problem.
The norm would be most systems/vehicles. With most systems venting the cabbin gains SPL, not only to the ear but also on the sensor in most common placements (Headrest, Dash, Kick). There in your statement is false and that is exactly what I was disproving.

//content.invisioncic.com/y282845/emoticons/fyi.gif.9f1f679348da7204ce960cfc74bca8e0.gif any time you vent the cabbin with out have the system completely open you are essentially creating a bandpass enclosure.

According to you, putting a sensor in a bandpass box then plugging the port will be louder than unplugging the port with the sensor in the box. I'm sure we can agree that isnt true.

You weren't arguing that before- you said this:

....because all sound is is ambient pressure variations...I'm talking about the rooms as a whole. If you open a window you give the pressure a place to exit and an actual wave is formed.

So by your last statement, you were wrong since Audioholic was arguing the increase comes from the creation of a port and bandpass effect- what you just agreed to.

Heres what Audioholic said before too-

I dont know what your problem is, but I stated whats considered to be the most widely accepted theory/reason behind louder bass with the windows down (bandpass situation) and you come at me like I have no clue what Im talking about. Whatever.

 

[CBFryman2 5,000+ posts]

AudioHolic is right- rolling down windows often makes your car louder by making your sealed or ported box a much larger 4th or 6th order (respectively). Its not because the pressure can escape. In fact- that would be without a doubt the opposite of what you want. SPL is a measure of pressure created by sound, if the pressure is allowed to escape, you loose dBs.
Look up on google how scientist recreate extremely loud SPLs- its not by building rooms with holes or by placing the speaker in the middle of a field so pressure can escape.

Hemholtz Resonator...

kthxbi.

 

[CBFryman2 5,000+ posts]

You weren't arguing that before- you said this:


So by your last statement, you were wrong since Audioholic was arguing the increase comes from the creation of a port and bandpass effect- what you just agreed to.

I never disagreed to that.

Hemholzt Resonator.

kthxbiagin.

 

[Relax 10+ year member]

I never disagreed to that.

Hemholzt Resonator.

kthxbiagin.

You specifically said the increase was from letting the pressure escape. Audioholic said fromt he beginning it was due to the creation of a port or bandpass enclosure. Now you are changing your tune. I could care less- its just that its all there in the thread even quoted for you to see.

 

[CBFryman2 5,000+ posts]

You specifically said the increase was from letting the pressure escape. Audioholic said fromt he beginning it was due to the creation of a port or bandpass enclosure. Now you are changing your tune. I could care less- its just that its all there in the thread even quoted for you to see.

No I'm not changing my tune. How does a Hemholtz resonator work? A columb of air is vented and interacts with a standing cusion of air. How does a ported enclosure work. SAME WAY!

OMFG is there a pattern?

Hey, how does that bandpass work, oh that's right...a columb of air is vented (see an anode where the new wave can exist depending on how it interacts with the standing air to determine 'tuning') and resonantes to interact with the standing cusion of air.

OMG, window is opened, a columb of vented air forms and OMFG it interacts with the standing cushion of air and gets louder than if the vehicle was sealed up.

 

[CBFryman2 5,000+ posts]

Also:

Why is a ported enclosure often called a vented enclosure?

Why are ports sometimes called vents?

What is a standing wave and how can it affect SPL?

How and why do Nodes and Anodes exist and how do they affect SPL?

 

[Relax 10+ year member]

LOL- you are still arguing this?

Earlier in the thread you clearly stated the increase in loudness from rolling down the windows of the car was due to allowing the pressure to escape. Audioholic said it was due to creating a bandpass effect. You were wrong and he was right.