Any device to measure sound frequency below 20 Hz?

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Discussion Overview

The discussion revolves around the search for devices capable of measuring sound frequencies below 20 Hz. Participants explore various technologies and methods, including accelerometers and microphones, while addressing sensitivity requirements and signal processing needs.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant inquires about devices for measuring sound frequencies below 20 Hz.
  • Another suggests using an accelerometer, mentioning a specific IC that can output a voltage proportional to acceleration, and asks for further advice on displaying frequency in Hz.
  • A participant recommends the Analog Devices ADW22035Z accelerometer, noting that it outputs a waveform and requires bolting to a vibrating object for effective measurement.
  • There is a suggestion that signal processing is necessary to obtain frequency measurements, with options for either purchasing expensive solutions or building a more complex setup.
  • One participant expresses the need to measure sound frequency without bolting a device to a vibrating object and seeks alternative suggestions.
  • A suggestion is made to use electret microphones or an array of them, with the caveat of needing larger coupling capacitors and a higher gain amplifier.
  • Another participant proposes creating a tuned cavity to enhance sensitivity to low frequencies, while also questioning the necessity of tuning for broader frequency ranges.

Areas of Agreement / Disagreement

Participants express various viewpoints on suitable devices and methods for measuring low-frequency sound, with no consensus reached on a single solution. Multiple competing approaches are discussed, indicating ongoing uncertainty and exploration.

Contextual Notes

Participants mention specific requirements such as sensitivity levels and the need for signal processing, which may influence the effectiveness of the proposed solutions. The discussion includes assumptions about the capabilities of different devices and their applicability to the problem at hand.

oem7110
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Does anyone have any suggestions on what device can measure sound frequency below 20 Hz?
Thanks in advance for any suggestions
 
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How sensitive does it need to be?
What about an accelerometer?
I "built" one using a single IC a few weeks ago, there are single ICs out there that only require a +5V supply and will give you a buffered voltage out that is proportional to the acceleration. Very easy to use.

(all I did was to solder 3 wires to the chip, and then I glued the whole thing to the top of a screw to make it stable and easier to attach to things)
 
f95toli said:
How sensitive does it need to be?
What about an accelerometer?
I "built" one using a single IC a few weeks ago, there are single ICs out there that only require a +5V supply and will give you a buffered voltage out that is proportional to the acceleration. Very easy to use.

(all I did was to solder 3 wires to the chip, and then I glued the whole thing to the top of a screw to make it stable and easier to attach to things)

Sensitive is around 1-2 Hz buffer range.
I also need to display the frequency in Hz, could you please give me any suggestions on what kind of IC I need and device to display the Hz in number? where can I purchase it online?
Thanks in advance for any suggestions
 
Last edited:
I used an Analod Devices ADW22035Z

http://www.analog.com/en/mems-sensors/low-g-accelerometers/adxl103/products/product.html

This will give you a signal out, but it will just be the waveform (although that will of course be true for a microphone as well). Note that an accelerometer measures vibrations , i.e. you need to bolt it to something that is vibrating.

If you want the frequency you need some signal processing as well, either you can but something (expensive) or build it (complicated unless you are good at DSP).
Alternatively, you could connect the accelerometer to a computer using a DAQ (about £100) or even the line-in input of a soundcard if you happen to have a card with a frequency response below 20 Hz; and the do the signal processing using software.
 
f95toli said:
This will give you a signal out, but it will just be the waveform (although that will of course be true for a microphone as well). Note that an accelerometer measures vibrations , i.e. you need to bolt it to something that is vibrating.

I want to measure sound frequency, and cannot bolt device into object that is vibrating.
Do you have any suggestions what device I should use and can purchase it available on market?
Thanks you very much for any suggestions
 
Last edited:
Have you tried an electret microphone, or an array of electret microphones? You may need to use larger coupling capacitors and a higher gain amplifier, but I don't see why it wouldn't work.
 
For a good solution to this problem it would be good to know a few more details - like what range of frequencies is involved and what level of sound. You say you haven't anything to 'bolt something to" but you could very easily make a tuned cavity (box with a hole in - or an old sub-woofer, cannibalised) that could couple your sound to a microphone, making it very sensitive to the low frequency. Tuning would not be of such benefit if you need to measure more than a narrow frequency range (unless you could trim it each time).
 

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