Measuring the Resonance Frequency of common objects

[NuclearFusi0n]

I was wondering how the resonance frequencies of objects is measured, and how i could measure them.
is it possible to measure the resonance frequency of a live item?

thanks

 

[bizmark]

heh.... I was wondering this lately... sitting around on campus watching girls walking by... it seems that there's a natural frequency for, er, bouncing when they're walking at *exactly* the right speed (usually walking pretty fast but still short of running/jogging), there can be some extreme bouncing going on. Of course it would vary from girl to girl, depending on certain characteristics...

but to the topic, what exactly are you talking about measuring? I would just wait until it hits the resonant frequency (indicated by much greater amplitude -- you should be able to tell by looking at it), and (if feasible) have the oscillating object hit against some switch that starts a timer, or trip a laser beam connected to a sensor. You could estimate the frequency with a simple stopwatch, but for any sort of accuracy you'll need a timer that is set off by some triggering apparatus.

Or wait, are you talking about the *acoustic* resonant frequency of an object? If so, you'd need a device (laser sensor?) that will take very precise measurements of very tiny movements (vibrations). Point it at the object. Get a wide-range, loud sound system.... turn it up and do a frequency sweep from say 10Hz to 1kHz. Plot the amplitude (of the object's vibration) vs. frequency of the sound you're emitting.... any frequency where the amplitude rises suddenly, would indicate a resonance frequency. You possibly could do this without a special sensor, just by touching the object. Things like desks and walls will often vibrate enough to feel them when you hit their resonant frequencies. Most of the time you shouldn't feel it vibrating at all... then when you hit a resonant frequency you should feel it vibrating.

In general I don't know if living items are uniform enough to have a single resonant frequency. Probably your femur has a certain resonant frequency, which is different from that of your skull, which is different from that of your stomach, etc. I know that I get a funny feeling in my stomach sometimes when I'm at the movies or someplace where there's really loud bass at a certain frequency, but usually it's just my stomach and no other part of my body.

 

[NuclearFusi0n]

acoustic resonance frequency of a human body part is waht i'm trying to measure. basically, i want to, for novelty purposes, play a tone that can make your tongue shake like crazy. Think going down to 10Hz is low enough? I'm sure a couple of 15" or 18" drivers can hit 10Hz pretty easily in the right enclosure.

 

[CTho9305]

Originally posted by: NuclearFusi0n1
acoustic resonance frequency of a human body part is waht i'm trying to measure. basically, i want to, for novelty purposes, play a tone that can make your tongue shake like crazy. Think going down to 10Hz is low enough? I'm sure a couple of 15" or 18" drivers can hit 10Hz pretty easily in the right enclosure.

how about the resonance frequency of, say, HIV?

 

[bizmark]

Originally posted by: NuclearFusi0n1
acoustic resonance frequency of a human body part is waht i'm trying to measure. basically, i want to, for novelty purposes, play a tone that can make your tongue shake like crazy. Think going down to 10Hz is low enough? I'm sure a couple of 15" or 18" drivers can hit 10Hz pretty easily in the right enclosure.

hmmm I don't know about 10Hz for the tongue.... You're essentially getting into mechanical vibrations at that point.... I wouldn't consider it sonic any more. I think that your best luck will be somewhere from 50-200Hz.... and it'll probably vary from person to person. I think it'd be cool to have something that resonates with your natural vocal frequency (corresponding to the length of your larynx maybe?) that makes your throat vibrate. Anyway, I guess you should just find a big@ss subwoofer and sit down next to it, while running high-amplitude frequency sweeps until you feel your tongue vibrating wildly.... *shrug*

cool related technology

Quote from the latest issue of Sound and Vision (editorial content not available online):

Dismissing the directions entirely, I twisted off the suction cup and applied the sound exciter element, about the size of a watch battery, to the top of one of my lower incisors. [...] My mouth cavity produced the best soundboard yet!

For $50 it'd be cool to have music in your mouth

 

[glugglug]

10Hz is in the right range for what I think you are looking for.

It's much lower than the resonating frequency of something as small as your tongue would be, but subsonics (below 20Hz audio) is actually frequently used in movies & such (especially horror films) to provoke autonomic responses associated with different emotions.

It was pretty blatant with Halloween: Resurrection - the movie itself wasn't scary it was funny. But you could literally smell the "fear" induced by the sound on the people walking out of the previous showing.

As far as literally resonating the tongue: even if you were able to find a frequency that vibrates it well, the pitch would be high enough that for an amplitude that gives your desired effect I think you would blow your eardrums first.

Bizmark: ROFL great link! One question though: how long before someone tries to use their ass as a soundboard?

 

[dkozloski]

The UCLA pep band has is configured so that they resonate the entire Pauly Pavilion. If you're sitting in the stands the sensation is similar to riding a motorcyle turning about 12,000 RPM. I strongly suspect that this is not by accident. I saw a basketball game between UCLA and Notre Dame about 20 years ago in Pauly and as good as the game was I still remember how magnificant that band sounded and felt.

 

[blahblah99]

I believe the resonant frequency of human beings is somewhere in the single digit area. The US military and law enforcement have been working on such a device that could distort a person enough that he wouldn't be able to perform simple tasks with that device pointed at him. If I could find a link, I'll share but I remember seeing that on TLC channel once on an episode about riot control.

 

[SuperCyrix]

2.4 GHZ is the natural frequency for all human body parts

 

[glugglug]

Super: ROFL is that the frequency of a Microwave to resonate water molecules?

That has interesting implications for SATA -- since it's serial 2.4GHz will be the required signaling rate for SATA-300.