The noise tag has no wiki summary.
12
votes
2answers
234 views
Maximum delay for effective active noise cancelling?
Active noise cancelling reduces unwanted sound by sending the inverted phase of the original phase:
(Source: Wikipedia)
Theoretically, this seems logical to me. However, in real life, the ...
5
votes
3answers
282 views
Why does inverting a song has no influence?
I inverted the waveform of a given song and was wondering what will happen.
The result is that it sounds the exact same way as before.
I used Audacity and doublechecked if the wave-form really is ...
5
votes
2answers
175 views
Modeling stochastic process with frequency-dependent power spectrum
I'm trying to model of Johnson-Nyquist noise propagation in a nonlinear circuit. An ideal (linear) resistor can be modeled very nicely by the Fokker-Planck equation (equivalently, the drift-diffusion ...
4
votes
1answer
60 views
Do error checking costs of quantum computing shrink BQP?
BQP is the set of problems solvable in polynomial time for a given error tolerance, and it is suspected to be larger than P (and BPP, which is probably equal to P). However, inability for the gates to ...
4
votes
4answers
196 views
Friction at zero temperature?
By the fluctuation-dissipation theorem (detailed-balance for Langevin equation), $$\sigma^2 = 2 \gamma k_B T$$ where $\sigma$ is the variance of noise, $\gamma$ is a friction coefficient, $k_B$ is ...
3
votes
1answer
702 views
Signal-to-noise ratio of the difference between two signals
Something tells me this must be a fairly simple question, but I have somehow been unable to find an answer to it. In short: I need to calculate the difference between two signals, A and B, each one of ...
3
votes
2answers
316 views
why isn't the variance of Fano noise proportional to the number of photon arrivals?
I've been reading "Photon Transfer" by James Janesick and in Chapter 3 (http://spie.org/samples/PM170.pdf) he describes the various sources of noise in a CCD. Basically, incoming photons interact with ...
2
votes
2answers
1k views
Decibel level addition of multiple noise sources
If I have four computer fans of which each is said to run at 46 dB, and they run close to each other, how loud is the whole system?
I somehow recall from my physics course that 10 decibel ...
2
votes
2answers
516 views
Generating Pink Noise
I've generated some white noise in Excel by using the formula
$$2*\mathrm{Math.RAND}()-1$$
I would now like to create some pink noise. I believe this is done by applying some sort of filter to the ...
1
vote
2answers
147 views
total noise power of a resistor (all frequencies)
Let's calculate the power generated by Johnson-Nyquist noise (and then immediately dissipated as heat) in a short-circuited resistor. I mean the total power at all frequencies, zero to infinity...
...
1
vote
2answers
128 views
What is the fundamental reason for noise?
I have read that noise is a result of there being "no such thing as a perfect one-way valve". That energy transfer is never perfectly one-way; there will always (at some level) a finite flow of energy ...
1
vote
2answers
76 views
Any noise slowly starting to take effects?
I am studying a system subject to random noise, or a system driven by some noise, for example, heat flow or wave propagation perturbed by noise. I would like to know if there is a real system where ...
1
vote
2answers
470 views
Noise amplitude increases as sample rate increase
I am testing the material properties of some very low stiffness materials.
I'm using a force probe connected to software, sensing at about a hundredth of a gram of force.
Now, what's interesting is ...
1
vote
1answer
77 views
noise level (units confusion)
i had a question in one of my classes regarding SNR in underwater acoustic channels. There are a couple of terms with the unit dB re uPa. I know it stands for dB ...
1
vote
0answers
105 views
Schottky and shot noise
I am looking for a little history on shot noise: when was it first predicted and first measured?
In particular, what was the role of Schottky? His 1918 paper "Über spontane Stromschwankungen in ...
0
votes
1answer
58 views
Numb3rs TV series - Antenna
Most of you might have watched the TV series 'Numb3rs'.
http://en.wikipedia.org/wiki/Numb3rs
In one of those episodes they were discussing about how to capture the contents on the screen of a ...
0
votes
1answer
52 views
Noise is a form of dissipation?
(Mechanical) noise is a form of dissipation? For example, when the computer fan turns it produces noise. This noise is a form of dissipation in addition to heat produced by the machine (computer)? If ...
0
votes
4answers
154 views
Isotropy and Noise
If you have a field which value is just Gaussian noise plus a constant do you call it isotropic?
there is no preferred direction
however it is not "the same" in all directions if "the same" means ...
-1
votes
1answer
39 views
High frequency sound transmission through plastic. I can't hear enough treble! [closed]
I have a large cylinder made of a rigid thick plastic with a speaker inside of it. I want to be able to hear high pitched / high frequency noise from the outside but I'm primarily hearing bass. The ...
