Hot answers tagged

9

Something like this? http://www.browninnovations.com/sound-dome/single-localizer-sound-dome As others have said, it is a speaker with a parabolic reflector to direct the sound down at the listener. You can make your own fairly easily: http://www.instructables.com/id/umbrelAudio-Sound-Dome-Umbrella/


8

With a description as vague as that, it was probably a parabolic reflector with a speaker at its focus. Pointed straight down, the "beam" of acoustic energy would be reflected from the floor right back into the "bell", with remarkably little leakage out the sides. A reflector with a diameter of 4-5 feet would be directional for frequencies down in the ...


3

Not really. Firstly the RA in RADAR stands for RAdio which covers significantly longer wavelengths than the visible light (an in some cases near infra-red) which cameras can detect. While light and radio are both part of the electromagnetism spectrum they are different parts of it and not interchangeable. While they are all part of a spectrum in terms of ...


3

I understand this question is about an event in Brazil and not the US. However, section 3.7.4 (Wave Loads) of the 2012 AASHTO LRFD Bridge Design Specifications simply says: Wave action on bridge structures shall be considered for exposed structures where the development of significant wave forces may occur. (This isn't a summary; that's literally the ...


3

As alephzero mentioned the difference is huge. I will explain mathematically and then physically. Mathematically, For any given partial differential equation of the form, $$A \frac {\partial^2\phi}{ \partial x^2} + B \frac {\partial^2\phi}{ \partial x \partial y} + C \frac {\partial^2\phi}{ \partial y^2} + \rm first\ derivative \ terms\ =0 $$ We get, $...


1

This is not really an answer but a hint. I agree with you that the impact is not limited to the small collision zone and propagates back and forth throughout the length of the beam and the vibration speeds can easily become supersonic, with the air cracking sound. What you are asking is called whiplash vibrations. Your beam is considered a whip and the rigid ...


1

The speed of sound is not a constant. The speed depends on the material the sound is traveling though. The speed of sound in aluminum, for instance, is roughly 20 times faster than air. If the microphone is mounted in a solid mount connected to the sound source, then the sound wave can propagate to the transducer through the mount faster than through the air....


1

Since this question is addressed around COVID-19, which is trending these days this response is focused on COVID-19 and using electronics to destroy the virus. The response is focused around destroying any live COVID-19 on surfaces as mentioned in comment. Soap works best to destroy the virus. Here is good explanation. How soap kills the coronavirus? ...


1

This is a pretty straightforward calculator: https://www.engineeringtoolbox.com/adding-decibel-d_63.html Basically noise level is dictated by your 2 loudest sources, so 50 dB + 40 dB (assuming they are at or near the same location) would result in about 50.5 dB.


1

The standard rule of thumb for adding decibels is that doubling the sound power increases the dB reading by +3dB. Using an on-lone calculator for adding dB's, we find that adding two sound sources that differ in strength by 10dB yields a dB total of 40.25dB. To the human ear, a difference of 0.25dB is completely inaudible.


1

So, after a little googling around. Cellphones typically transmit on 3/4 G at between 0.3 and 3 W - subject to tower location & interference. The out put power is managed by the cell tower. Mobile phone wifi is typically 15mW. If we assume min output for 3/4 G at 300 mW (0.3 W) this is, at best, 20 times greater than wifi at 15 mW. On that basis I ...


1

Some large buildings have a transformer attached to them for the mains supply for all apartments. The vibrations are probably being transmitted via harmonic resonance due to acoustic amplification. This may have been why previous owners sold the property. Human body operates at 25Hz which means harmonic octave frequencies are more noticeable to us. It may ...


1

All channels good but: National standards can control some parameters (gain, numbers of channels, gain in channel ...). Gain of Channel 1 can be less in some cases. I have 19 visible ssids in my workplace so channel is best if it only my and have no neighbors. often if no activity wifi routers choose channel 6, and it`ll be the most loaded. often all ...


Only top voted, non community-wiki answers of a minimum length are eligible