# Questions tagged [acoustics]

Acoustics is the interdisciplinary science that deals with the study of all mechanical waves in gases, liquids, and solids including vibration, sound, ultrasound and infrasound. Applications of acoustics are for instance the audio and noise control industries.

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### Does special relativity also imply that speed of sound is constant for all observers irrespective of their relative motion?

I am reading lec15 The Special Theory of Relativity from the Feynman lectures. Poincaré made the following statement of the principle of relativity: “According to the principle of relativity, the ...
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### Why do airplanes sound louder when its cloudier?

I am from India, and now its monsoon season. Typically, during this time, the sky is filled with dark rain clouds. Me, along with several of my friends, have observed from childhood that the planes ...
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### Can taut membranes and strings that are clamped at both ends propagate non-standing waves?

I'm going through an introductory course in acoustics and I'm struggling with the intuition behind standing waves. When deriving solutions to the various wave equations we usually impose a boundary ...
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1 vote
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### Lamb wave derivation: Elastic wave propagation in a thin sheet

I am trying to follow the derivation for the phase velocity for elastic waves with large wavelengths compared to sheet thickness, propagating in a floating ice sheet, as described in Propagation of ...
455 views

### Which better conducts vibration: wood or metal?

For some reason I can't get a definitive answer on this. My bedroom is on top of a garage, and every time the garage door opens/closes, the old garage opener that's positioned on the ceiling vibrates ...
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### Is the Doppler Effect for sound waves with a moving source due to the fact that the wave speed is independent of the source?

The Doppler Effect is typically formulated as follows: $$f' = \dfrac{v \pm v_o}{v \mp v_s} \cdot f$$ The reason for the frequency increasing for observer moving towards source seems clear enough. It ...
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### An echo that sounds for years?

How exactly should I understand United Airlines Flight 2860's description and English Wikipedia? Namely, last sentence of the fourth chapter of the summary: The "echo" of the crash could be ...
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### Physical basis of "forced harmonics" on a violin

I have recently learnt of a somewhat novel violin technique, sometimes known as "forced harmonics", where, in a physicist's terms, instead of the normal N=1 stationary wave (fundamental mode)...
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### Sound Attenuation and Loss Factor

I am currently trying to explain the reasons for my sound transmission loss for my material selection and design. I am using polymers of different depths and currently in my model I'm considering ...
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### How can sound travel as a transverse wave?

We know that sound travels by each previous particle transferring its energy to the next successive particle. We also know that transverse waves are those waves in which particles move about their ...
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### Since waves are abstractions, does it even make sense to ask whether light is a wave? [closed]

All waves transmit energy. Water Waves Let's say you're in the middle of a calm pond and you start moving your hand up and down. Transverse "waves" are generated, and they propagate ...
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### Can we trust our ears in speech recognition in an audio file? [closed]

Can we trust our ears in speech recognition in an audio file?
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### How do shock waves reflect?

As seen in this picture, an oblique shock was reflected off of a solid wall. I understand that the flow has to turn to continue the shock, but how does this work when it gets to a wall? What happens ...
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### Why is transfer of heat very slow as compared to transfer of sound in solids?

If I heat a one-meter long iron rod at one end, the heat takes several seconds to reach the other end, while sound takes fractions of a second. Why is it so?
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### What is the pitch or air flow constant of a whistle?

I am making a whistle capable of making any sound and/or frequency based on a specific air flow, but despite my personal goal, What is the pitch or air flow constant of a whistle? I mean to express, ...
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### Question about Proportionality in Sound Equation (Pressure and Displacement Amplitude)

Why is intensity in terms of pressure amplitude inversely proportional to density and velocity: $I=\frac{\Delta p_\text{max}^2}{2\rho v}$, while in terms of displacement amplitude, it is proportional ...
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### We know that people can hear whether the water is hot or cold from the act of pouring, but have we ever considered the shape and material of the cup? [closed]

We know that one can hear whether water is hot or cold from the act of pouring, which is related to the viscosity of the water, the column of air inside the container, and the overall vibration of the ...
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### Validity of approximations in the derivation of sound waves from Newton's laws

In deriving the wave equation describing the displacement of air in the atmosphere usually some assumptions about the displacement function $\chi(x,t)$ are made. For example Feynman says: Now in ...
The definition of sound intensity is $I=P/S$, where $P$ is the power generated by the wave source and $S$ is the area over which the energy is transferred. Assuming conservation of mechanical energy ...