Is there a tool to measure resonant frequency?

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Discussion Overview

The discussion revolves around methods to measure the resonant frequency of wineglasses, focusing on the use of computer programs and microphones for quantitative analysis. Participants explore various tools and techniques, including software options and traditional methods.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant inquires about the availability of computer programs that can measure resonant frequency using a microphone and questions the sensitivity of the microphone for accurate readings.
  • Another participant suggests using Audacity and provides a link to a previous thread discussing its use.
  • Some participants recommend consulting with art and drama departments for sound analyzers designed for stage use.
  • There are mentions of using tuning forks and traditional methods, such as comparing the sound of the glass to piano notes, to determine resonance.
  • A participant expresses concern about the microphone's sensitivity, questioning whether it would be adequate for detecting the sound of the wineglass.
  • One participant shares their experience using Audacity and a computer oscilloscope to capture waveforms but seeks guidance on analyzing these waveforms to find the resonant frequency.
  • Another participant critiques the quality of the waveforms obtained, suggesting issues with saturation or sampling rates and provides advice on measuring the waveform period to calculate frequency.
  • There is a discussion about performing spectral analysis to identify the resonant frequency from the captured data.

Areas of Agreement / Disagreement

Participants express various methods and tools for measuring resonant frequency, but there is no consensus on the best approach or the effectiveness of the microphone sensitivity. The discussion remains unresolved regarding the optimal technique for analysis.

Contextual Notes

Participants mention limitations related to microphone sensitivity and the quality of audio recordings, which may affect the accuracy of frequency measurements. There are also unresolved questions about the best methods for analyzing waveforms and determining resonant frequencies.

michiru
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For a science investigation, I want to investigate how different factors affect the resonant frequency of wineglasses, however, I need some way to measure the frequency quantitatively. Is there some kind of computer program that can do so through the computer microphone? And if so, would the microphone be sensitive enough to detect such a sound and give an accurate reading of the frequency?
 
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You can download some simple, free, programs to use with the audio card.
For example:
http://www.electronics-lab.com/downloads/pc/001/index.html
 
Dang! I was going to suggest a set of tuning forks! I'm getting too old!
 
Another "old school" approach is to set the wine glass by a (tuned) piano, put your ear next to the opening and listen for resonance as you compare it to the piano notes. (Lightly tap the glass with a pencil to hear its resonant freq.)

Look up the frequencies and you should be able to get pretty good measurements. Even if the wine glass frequency exceeds the high note on your piano you should be able to pick out the note compared to one or two octaves below. And you should be able to interpolate between keys to a half note by ear.

The human ear is a pretty darned good frequency analyzer all by itself.
 
Hi everyone, I like the idea of using Audacity and the free computer programs, but I am worried that the computer microphone will not be sensitive enough to detect the sound of the wineglass? Would this be a problem?
 
Please check the link I posted, michiru: that is exactly what I did!

I used the trick where you wet your finger and rub it around the rim of the glass and held the mic next to it.
 
russ_watters said:
Please check the link I posted, michiru: that is exactly what I did!

I used the trick where you wet your finger and rub it around the rim of the glass and held the mic next to it.

Hi, I did a test, with audacity and a computer oscilloscope and got some nice waveforms, but I am not sure how to analyze these waveforms to determine what the resonant frequency is? I tapped an empty wineglass with a spoon near the microphone and got these:
 

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  • #10
The second image looks useless. Either it is saturating (signal is actually too loud) or it is not sampling fast enough or both. The first image looks like it might be good but you need to zoom into a small segment.

You should see a decaying sinusoidal waveform. You should be able to then determine the period of one cycle.

Zoom in, measure the distance between 10 peaks of the waveform and divide by 10 to get an average period. The frequency is then 1 over the period.

Can you post a zoomed in image from the audacity sample?
 
  • #11
jambaugh said:
The second image looks useless. Either it is saturating (signal is actually too loud) or it is not sampling fast enough or both. The first image looks like it might be good but you need to zoom into a small segment.

You should see a decaying sinusoidal waveform. You should be able to then determine the period of one cycle.

Zoom in, measure the distance between 10 peaks of the waveform and divide by 10 to get an average period. The frequency is then 1 over the period.

Can you post a zoomed in image from the audacity sample?

I do see part of a sinusoidal waveform. As seen in the last recording in the screenshot.

Don't I need to do a spectral analysis or something?
 

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  • #12
michiru said:
Hi, I did a test, with audacity and a computer oscilloscope and got some nice waveforms, but I am not sure how to analyze these waveforms to determine what the resonant frequency is?
Analyze -> plot spectrum
 
  • #13
russ_watters said:
Analyze -> plot spectrum

Is the value of the first peak the resonant frequency then?
 

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