8 votes
Accepted

Ultrasonic whistling

You can find everything beautifully explained in this website on brass instruments: https://newt.phys.unsw.edu.au/jw/brassacoustics.html A short version is that for ultrasonic (>20 kHz) vibrations ...
ondas's user avatar
  • 815
4 votes

Ultrasonic whistling

The claim is almost certainly false. The normal range of human whistling is from 2-4 KHz. For someone to whistle in the ultrasonic range would require him to reduce the space between tongue and ...
Tom Williams's user avatar
4 votes

What's the limit on the length of string that can be pulled by a person?

There are two big practical problems with using string for signalling - it stretches, and it breaks easily. You can replace the string with wires or metal bars - this was the system used for ...
gandalf61's user avatar
  • 50.1k
3 votes

What's the limit on the length of string that can be pulled by a person?

The current set-up faces several issues: The enemy could damage our wire network or there might be some internal fault, similar to the scene at 2:50. Earth's curvature imposes limitations on the ...
Harjot Dhillon's user avatar
2 votes

How to standardize the energy of a Dirac delta function relative to sample rate (width) and amplitude?

For a sampled signal, a one sample pulse has a white DTFT (discrete time Fourier transform) spectrum. A wider pulse has a high frequency cutoff. The energy in the pulse is proportional to its duration,...
John Doty's user avatar
  • 20k
2 votes
Accepted

How do the amplitudes of longitudinal wave harmonics in a string vary with excitation (pluck) position?

Short Answer The harmonic amplitudes of the longitudinal "pluck" would follow the same pattern as the transverse pluck. Longer Answer Without having to rederive the harmonic amplitudes for ...
Michael M's user avatar
  • 1,765
1 vote

How wave speed affects perception?

They would be waves traveling through different media with their frequencies set so that they have the same wavelength. So you would see them as different colors or hear them as different pitches.
Dale's user avatar
  • 97.7k
1 vote

EM wave emission from earphone wires due to varying current signal

It will radiate as Joe Doty points out unless the wire is shielded, with the neutral return line wrapped around the hot (signal) line and a thin layer of insulation between. Shielded lines at audio ...
niels nielsen's user avatar
1 vote

EM wave emission from earphone wires due to varying current signal

Yes. It's a very inefficient antenna. You'll never detect a radiated field even though in theory it's present.
John Doty's user avatar
  • 20k
1 vote
Accepted

If a damped mass-spring oscillator is equivalent to a resonant bandpass filter, then in audio signal terms, what is the input signal for both?

It depends on how you set up the mechanical equation, but assuming it is a displacement for both, the input will be forced displacement of the base of the spring and the output will be the ...
Poisson Aerohead's user avatar
1 vote

Measuring the tension of a drumhead

As Chemomechanics has pointed out and as discussed in some detail here, the equations are related to the solution of the wave equation on a circular membrane. The solution corresponding to the ...
Puk's user avatar
  • 13.4k
1 vote

When a tuning fork is struck, how does the struck tine induce vibrations in the secondary tine?

Coming in a bit late. Perhaps, for non-scientists, this less-precise perspective might be useful. Activation: When one tine/arm of a tuning fork is struck, or is itself struck against a heavy object, ...
cTen's user avatar
  • 21

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