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In Reply to: RE: Aren't we getting a little tiny bit off topic here? Hey, it's time for a Pop Quiz! posted by geoffkait on February 26, 2023 at 12:18:49
OK, Pop*-? I vote Squirt in bottles and Nehi Grape soda
How a Helmholtz resonator can work to subdue a room mode is easy to explain / envision.
A standing wave dictates the pressure maximum is at the boundary which acts something like a mirror or better, what concrete represents when a super ball hits it.
IF one measured the pressure in the corner, you would see at the condition that you have a standing wave, you have a peak in the pressure in the corner. The down side is there are also Nulls produced where the bass is gone. IF you drilled a hole in the corner to the outside world, that would reduce the pressure at resonance and reduce the sharpness and magnitude of the standing wave .
That "hole" will let bugs in so instead, one makes a Helmholtz resonator (a volume of air in a container and Vent or duct to the room, like a vented box woofer with no woofer). This has the same resonant F as the room mode and so, at that frequency is "like" a duct to the outside in that at least at that one frequency, the air in the port is VERY easy to move like a duct to the outside and not ridged like a wall pressure boundary.
This is all i can offer
Follow Ups:
Sorry, but that's completely unresponsive to my questions. Perhaps try again later. Anyone can Google Helmholtz resonator.
"Anyone can Google Helmholtz resonator. "
I guess part of my point what why it works when placed in a corner, sitting out in the middle of as room, not in a pressure maximum, it doesn't have anywhere near the same effect.
AS far as RF, my phone "hears" 2.4GHz but my ears don't
Pretty weird you would believe RF is not an issue in audio. Oh, well moving right along. As for pressure maximums, they can be anywhere in the room, you won't know for sure where exactly they are in the room unless you map out the entire 3D space of the room. This is why instructions are provided with tiny little bowl resonators, to minimize the effort necessary to find ideal locations. Obvious no two rooms are the same acoustically.
"Pretty weird you would believe RF is not an issue in audio. Oh, well moving right along."
Yes but what i said was "AS far as RF, my phone "hears" 2.4GHz but my ears don't"
So are you suggesting yours do?
You are late to the many posts on this forum during most of last year here on the dodgy subject of what is the audio signal and how does electricity in audio circuits work?The short answer is yes, your ears hear the *effect* of Radio Frequency interference. Obviously we don't hear RF directly, that would be absurd. They aren't acoustic waves.
The reason is because radio frequencies are *electromagnetic waves*. And external electromagnetic waves produce noise and distortion in audio signals because audio signals are themselves, you guessed it, electromagnetic in nature. Poynting vector with E and B fields.
Analogous to the deleterious effects of RF on our hearing is the effect of Very Low Frequency seismic type vibration, also outside nominal 20-20k Hz audio frequency bandwidth. Seismic type vibration is around 1 Hz - 20 Hz approximately.
The ball is in your court.
Edits: 02/28/23 02/28/23 02/28/23
everything matters... we just do not know what to measure and there is NO such thing as objective as we do not possess COMPLEAT knowledge, therefore all is subjective. Philosophy 101.
The Mind has No Firewall~ U.S. Army War College.
Nt
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