Does sound cancel each other out?

[OutHouse]

Originally posted by: Howard

Originally posted by: Citrix
so what is ANR (Active Noise Reduction)?

The equal-amplitude reproduction of a noise, but 180 degrees out of phase with the noise itself so as to null the sound.

ok... so how is this different than the OP question?

 

[TuxDave]

Originally posted by: Citrix

Originally posted by: Howard

Originally posted by: Citrix
so what is ANR (Active Noise Reduction)?

The equal-amplitude reproduction of a noise, but 180 degrees out of phase with the noise itself so as to null the sound.

ok... so how is this different than the OP question?

He was asking if a plane's sound will nullify a car's sound. Generally speaking, they will not. ANR produces a very specific sound that's designed to nullify another sound. It's very unlikely to have two random sounds that happen to cancel each other out.

Originally posted by: AlienCraft

Mathematically speaking, you are correct.
In practical application of the mathematics, the physics of the devices comes into play.

I'm not quite sure why there's even a discussion about practical applications. I guess if the OP asked does 2x the input power to a speaker = 2x the output sound power it could be relevant. But sure, I know what you're getting at and I'm not gonna bother arguing this point since it's trivial.

 

[OutHouse]

Originally posted by: TuxDave

Originally posted by: Citrix

Originally posted by: Howard

Originally posted by: Citrix
so what is ANR (Active Noise Reduction)?

The equal-amplitude reproduction of a noise, but 180 degrees out of phase with the noise itself so as to null the sound.

ok... so how is this different than the OP question?

He was asking if a plane's sound will nullify a car's sound. Generally speaking, they will not. ANR produces a very specific sound that's designed to nullify another sound. It's very unlikely to have two random sounds that happen to cancel each other out.

AHHH SOOOOO. thanks.

 

[FrustratedUser]

Originally posted by: bigalt
sound waves have phases and can cancel out, if that's what you mean.

but as for how loud they are, the way the decibel scale works is such that doubling the sound output raises the decibel level by +3.

so 5 dB + 5 dB = 8 dB or so

No, 5dB + 5dB = 10dB. 8dB will be twice as loud as 5dB.

 

[AlienCraft]

Originally posted by: Citrix

Originally posted by: Howard

Originally posted by: Citrix
so what is ANR (Active Noise Reduction)?

The equal-amplitude reproduction of a noise, but 180 degrees out of phase with the noise itself so as to null the sound.

ok... so how is this different than the OP question?

The OP's question involves dissimilar sounds. In order for noise to cancel so as to render silence (or minimal detectable sound) the waveforms would have to match almost identically.
In Sound Masking, we use sound with a broad enough spectral component to cover conversation or extraneous external noise.

 

[Viper GTS]

Originally posted by: Citrix

Originally posted by: TuxDave

Originally posted by: Citrix

Originally posted by: Howard

Originally posted by: Citrix
so what is ANR (Active Noise Reduction)?

The equal-amplitude reproduction of a noise, but 180 degrees out of phase with the noise itself so as to null the sound.

ok... so how is this different than the OP question?

He was asking if a plane's sound will nullify a car's sound. Generally speaking, they will not. ANR produces a very specific sound that's designed to nullify another sound. It's very unlikely to have two random sounds that happen to cancel each other out.

AHHH SOOOOO. thanks.

To expand on that, in general two repetitive noises (ie a car engine or plane at steady throttle) will have points where constructive interference occurs & some where destructive interference occurs. This can produce a repeated pattern of loud/soft noises, typically heard as a pulsing or thumping if the noises are loud enough. Pretty interesting actually.

Viper GTS

 

[AlienCraft]

Originally posted by: TuxDave

Originally posted by: Citrix

Originally posted by: Howard

Originally posted by: Citrix
so what is ANR (Active Noise Reduction)?

The equal-amplitude reproduction of a noise, but 180 degrees out of phase with the noise itself so as to null the sound.

ok... so how is this different than the OP question?

He was asking if a plane's sound will nullify a car's sound. Generally speaking, they will not. ANR produces a very specific sound that's designed to nullify another sound. It's very unlikely to have two random sounds that happen to cancel each other out.

Originally posted by: AlienCraft

Mathematically speaking, you are correct.
In practical application of the mathematics, the physics of the devices comes into play.

I'm not quite sure why there's even a discussion about practical applications. I guess if the OP asked does 2x the input power to a speaker = 2x the output sound power it could be relevant. But sure, I know what you're getting at and I'm not gonna bother arguing this point since it's trivial.

The OP's question involves sound from machinery.
The physical characteristic of HOW the sound comes from the devices is relevant. Since they may have different resonant characteristics, projections due to the shape of the item, it becomes relevant to discuss it in more simple terms that can be quantified such as provided by different speaker types.
That is why I used the different speaker types to illustrate my point.

 

[TuxDave]

Originally posted by: FrustratedUser

Originally posted by: bigalt
sound waves have phases and can cancel out, if that's what you mean.

but as for how loud they are, the way the decibel scale works is such that doubling the sound output raises the decibel level by +3.

so 5 dB + 5 dB = 8 dB or so

No, 5dB + 5dB = 10dB. 8dB will be twice as loud as 5dB.

What? 10dB will appear twice as loud as 5dB but 8dB will actually contain twice as much power as 5dB.

 

[TuxDave]

Originally posted by: AlienCraft

The OP's question involves sound from machinery.
The physical characteristic of HOW the sound comes from the devices is relevant. Since they may have different resonant characteristics, projections due to the shape of the item, it becomes relevant to discuss it in more simple terms that can be quantified such as provided by different speaker types.
That is why I used the different speaker types to illustrate my point.

Umm.... ok. Sure.

 

[AlienCraft]

Originally posted by: TuxDave

Originally posted by: AlienCraft

The OP's question involves sound from machinery.
The physical characteristic of HOW the sound comes from the devices is relevant. Since they may have different resonant characteristics, projections due to the shape of the item, it becomes relevant to discuss it in more simple terms that can be quantified such as provided by different speaker types.
That is why I used the different speaker types to illustrate my point.

Umm.... ok. Sure.

Is that an ambivalent "ok" or what?
There seems to be a confusion of the Decibel in terms of the way it's being used. Since we are talking about Sound Pressure Level (dbM) and POWER (db) in the same conversation, there may be some confusion generated by using the term in reference to loudness as the OP described it.

 

[TuxDave]

Originally posted by: AlienCraft

Originally posted by: TuxDave

Originally posted by: AlienCraft

The OP's question involves sound from machinery.
The physical characteristic of HOW the sound comes from the devices is relevant. Since they may have different resonant characteristics, projections due to the shape of the item, it becomes relevant to discuss it in more simple terms that can be quantified such as provided by different speaker types.
That is why I used the different speaker types to illustrate my point.

Umm.... ok. Sure.

Is that an ambivalent "ok" or what?
There seems to be a confusion of the Decibel in terms of the way it's being used. Since we are talking about Sound Pressure Level (dbM) and POWER (db) in the same conversation, there may be some confusion generated by using the term in reference to loudness as the OP described it.

It's 'ok' as in fine. As for your comment on dBm... unless there's a difference between dBm and dbM, then I thought dBm was dB just with a different 0dB reference.

 

[AlienCraft]

Originally posted by: TuxDave

Originally posted by: AlienCraft

Originally posted by: TuxDave

Originally posted by: AlienCraft

The OP's question involves sound from machinery.
The physical characteristic of HOW the sound comes from the devices is relevant. Since they may have different resonant characteristics, projections due to the shape of the item, it becomes relevant to discuss it in more simple terms that can be quantified such as provided by different speaker types.
That is why I used the different speaker types to illustrate my point.

Umm.... ok. Sure.

Is that an ambivalent "ok" or what?
There seems to be a confusion of the Decibel in terms of the way it's being used. Since we are talking about Sound Pressure Level (dbM) and POWER (db) in the same conversation, there may be some confusion generated by using the term in reference to loudness as the OP described it.

It's 'ok' as in fine.

cool

 

[TuxDave]

Originally posted by: AlienCraft

Originally posted by: TuxDave

Originally posted by: AlienCraft

Originally posted by: TuxDave

Originally posted by: AlienCraft

The OP's question involves sound from machinery.
The physical characteristic of HOW the sound comes from the devices is relevant. Since they may have different resonant characteristics, projections due to the shape of the item, it becomes relevant to discuss it in more simple terms that can be quantified such as provided by different speaker types.
That is why I used the different speaker types to illustrate my point.

Umm.... ok. Sure.

Is that an ambivalent "ok" or what?
There seems to be a confusion of the Decibel in terms of the way it's being used. Since we are talking about Sound Pressure Level (dbM) and POWER (db) in the same conversation, there may be some confusion generated by using the term in reference to loudness as the OP described it.

It's 'ok' as in fine.

cool

Actually... I added a little side question. What is the difference of dB and dBm. I always assumed dBm was dB but with a different 0 reference.

 

[AlienCraft]

Originally posted by: TuxDave

Actually... I added a little side question. What is the difference of dB and dBm. I always assumed dBm was dB but with a different 0 reference.

That is a reference to One milliwatt, as a standard for measuring signal strength.
There is also dbA and dbC which are references to different frequency response curves (weighting) for loudness measuring.

 

[TuxDave]

Originally posted by: AlienCraft

Originally posted by: TuxDave

Actually... I added a little side question. What is the difference of dB and dBm. I always assumed dBm was dB but with a different 0 reference.

That is a reference to One milliwatt, as a standard for measuring signal strength.
There is also dbA and dbC which are references to different frequency response curves (weighting) for loudness measuring.

That's what I thought. But you're saying that sound pressure is measured in dBm?

 

[AlienCraft]

Originally posted by: TuxDave

Originally posted by: AlienCraft

Originally posted by: TuxDave

Actually... I added a little side question. What is the difference of dB and dBm. I always assumed dBm was dB but with a different 0 reference.

That is a reference to One milliwatt, as a standard for measuring signal strength.
There is also dbA and dbC which are references to different frequency response curves (weighting) for loudness measuring.

That's what I thought. But you're saying that sound pressure is measured in dBm?

No, I'm saying that power that is used to measure a certain SPL is referenced in dbM, SPL is measured in dbA or dbC. The dbM measure keeps the "playing field" level.
edit: looking back on my post, I was using it improperly. sorry for adding confusion.