Laser Displacement Measurement of a Loudspeaker (100 Things #96)
Laser displacement measurement is a technique for measuring the peak displacement of a loudspeaker diaphragm at various power levels, frequencies or both. Did you know that SoundCheck can easily be configured to include a laser signal path? This makes it easy to correlate diaphragm displacement with electrical impedance and audio artifacts. In this short video, we demonstrate laser displacement measurements of a loudspeaker.
Laser Displacement Measurement
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Ready to try it for yourself? You can read more and download this laser displacement measurement sequence here.
More information on configuring SoundCheck for use with lasers is also available in the SoundCheck Manual.
Video Script: Laser Displacement Measurement of a Loudspeaker
Displacement lasers can be used to measure the peak displacement of a loudspeaker diaphragm at various power levels, frequencies or both. Did you know that SoundCheck can easily be configured to include a laser signal path? This makes it easy to correlate diaphragm displacement with electrical impedance and audio artifacts. Let’s take a look.
First, we create a Laser Signal Path in Calibration and once that’s done, a new calibrated device file for the instrument. The sensitivity of most lasers is expressed in Volts per Millimeter and in this case, our laser’s sensitivity is 100 volts per millimeter. After creating custom units, we can enter the sensitivity value, select a hardware channel and we’re ready to measure!
In this sequence, we’re using a stepped sine sweep starting at 1 kHz and ending at 20 Hz, and we’re also simultaneously measuring the impedance and frequency response of our speaker under test. The recorded time waveform from the laser can be analyzed just like any other waveform but there’s one additional post processing step required after analysis, converting the displacement level from RMS to peak.
As you can see, configuring SoundCheck for laser measurements couldn’t be easier. The resulting data can be used to study the displacement of the speaker under test and can even be used in conjunction with other SoundCheck measurements to calculate more advanced metrics such as Thiele-Small parameters. You can learn more about advanced speaker measurements on our website, www.listeninc.com.
