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1

Speakers are designed with a combination of filters that help correct for any resonance that is provided by the enclosure. When you take the back off, you change the resonance - so you will end up with "colored" sound. Usually, it is the lower frequencies that suffer, but without details about the actual enclosure it's hard to give a definite answer. See ...


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I'd like to start from mathematical description of the following process. At the end of my post I will give you a qualitative explanation. Mathermatical description of the motion in frequently oscillating field Actually, the problem you state can be generalized to the following one: Suppose you have a particle that moves in some force field that ...


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The answer seems to be that the levitating object is vibrating and pressure gradient is a function of time, but also of the position of the object. Suppose the object's has initially zero velocity, is located at a node, while the pressure gradient is maximal and pushing it upwards. The object accelerates upwards and the pressure gradient flips it's sign. ...


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Often the "speed of sound" is defined as the slope of the acoustic branch as the wavevector goes to zero (the "acoustic limit" -- where phonons behave like waves in a continuum material). So yes, there can be multiple speeds of sound. Two TA branches can converge as the wavenumber goes to zero, in which case they'd have the same "speed of sound". By the ...


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I suggest that you don't want to pass ultrasonic signals through air. I worked in an ultrasonic lab once and we used solid crystals and water to pass the signal.... I would suggest that this is the way to go rather than air send waves down metal rod perhaps and have water to couple to the sample if this is possible... or even a rubber foot if water is not ...


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There are as many branches of acoustic phonons as there are dimensions of the crystal, but they are not necessarily distinct. These three branches will each have a "speed of sound" associated with it, given by the gradient of the frequency-wavenumber graph at the origin. If these are different, it means that the speed of sound will be different in different ...


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His clothes, the music player and so on might of course move with him (supposing they would be able to withstand the rapid acceleration and decelleration involved, which I doubt), but the music player would have to play the music much faster all of a sudden for it to appear the same. It's entirely possible of course for Quicksilver to have a specially ...


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If you hit a tuning fork with a hammer, you provide a driving force. Once your hammer is no longer in contact with the tuning fork, there is no longer any driving force, and the fork vibrates at it's natural frequency.


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The speed of sound depends on the square root of temperature, so the refractive index is proportional to $T^{-1/2}$. Let's assume that the sound is emitted isotropically. During the day, the usual situation is that the temperature decreases with height. Thus the refractive index increases with height. This will tend to make sound waves emitted in the ...


1

Sound is a longitudinal wave whose amplitude stands for its "loudness". When sounds travels in medium, it attenuates, i.e. becomes less loud, exponentially, with an exponential coefficient, $\alpha$. So what you're actually interested in is the change in $\alpha$ with temperature. For newtonian fluid for example, this coefficient is equal to: $$\alpha = ...


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When sound propagates in the lower atmosphere it can travel through denser or thinner parts of air. This could cause a "portion" of the sound to bend upwards, making it harder to hear. Factors that could cause the bending are: wind speed and/or temperature that change based on altitude.For more info you can check this link. Additionally, wind sound can ...


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Same issue Here, I have a 4G tower 100m away in front of my windows and picking High pitched noise at frequencies of 4kHz, 6kHz and 8kHz. The noise appeared when the 3G cell towers were replaced by 4G towers. The best solution I found was to wrap the active speakers in an emergency blanket (all the faces except the one containing the speaker). This ...


1

Here's a simpler answer. Resonance is really all about the capture of energy into a system and its cyclic flow between potential and kinetic states. In mechanical systems we call these states potential energy and kinetic energy, but in electrical systems, as a another example, between magnetic and electrical fields. It's the rate of this cycling back and ...


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Natural frequency depends on the physical properties of a system. Some of the classical examples are masses attached to springs and pendula. For the former class, the basic model is based on Hooke's law, which translates into the differential equation (1D) $$m\ddot x + kx = 0,\qquad m,k > 0$$ where any sort of dissipative effect has been neglected. ...


0

That is what FM Radio works on. So lets say we have an entirely analogue setup - a mic as input (RJ talking for example) and that being broadcast over a 91 MHz Signal real-time = Audio wave over a High frequency carrier. There is no digitization as you are not sending 0s and 1s here. However Digital audio over FM has its advantages since the ...


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Sound is a pressure wave, alternating deviations of pressure from the equilibrium. So, depending on the medium in which the pressure wave passes, you can get either type of wave (longitudinal or transverse): In gases and liquids, the pressure deviations causes compressions and rarefactions, meaning these are longitudinal waves. In solids, the pressure ...


4

Yes, you can use the pressure generated by the sound wave or the energy it transmits. For example zero decibels is $10^{-12}$ W/m$^2$. I suspect the dB scale originated because the preception of volume in human hearing is logarithmic i.e. we perceive each successive doubling as a linear volume increment. The dB scale is also logarithmic and maps well onto ...



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