Tech Note 564 Detail

Measuring the speed of sound with an Xplorer GLX.

Affected Products:

PS-2002 Xplorer GLX

Measuring the speed of sound with an Xplorer GLX.

PASCO Solution:

Measuring an Echo with the GLX



  • wave guide: 1.5 m - 3.0 m long rigid tube, 10-25 cm in diameter (such as the WA-9495 Economy Resonance Tube.) (PVC or Cardboard are OK)
  • reflector: a hard plate large enough to cover one end of the tube to reflect the sound


  • clicker: a sound source that produces a brief sound with ultrasonic components
    (Snapping works well. Breaking a bubble pack bubble works even better.)


  1. Navigate to Home/Sensors (F4)/Microphone (F3)/Sound Sensor.
  2. Increasing the sampling rate to 50,000 Hz.
  3. Navigate to Home/Graph/Graphs(F4)/Scope Mode (3).
  4. Click Tools (F3)/Trigger (8)
  5. Press the right button, to set the trigger on a rising edge.
  6. Press the up button to move the trigger to 30000.
  7. Place the reflector at one end of the tube.
  8. With the GLX in one hand and the clicker in the other, both at the end of the tube opposite the reflector, press the play button to arm the GLX.
  9. Click.
  10. After a few seconds, press the play button again to stop the data acquisition.
  11. Expand the x-axis to see the initial waveform and its echoes.
    • Press the Scale/Move (F2) button to enter the scale-mode.
    • Use the right arrow button to expand the horizontal axis. (You should see the initial waveform and at least one other echo.)
  12. Calculate the speed of sound v by v = 2*L/T, where D is defined as the distance between the clicker and reflextor and T is defined as the time between the peaks of the emitted and reflected sound wavelets.
File Downloads:
echo.glx - ( 2 KB )
Configured GLX file for finding speed of sound

Creation Date: 03/15/2006
Last Modified: 05/20/2011
Mod Summary: