Proving Science

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Basic concept is to measure the speed of the sound using echoes and with the microphone build in notebook.


Apparatus and materials:

1. Notebook or device with microphone,

2. Sound editor e.g. Audacity

3. Paper or other material tube with known length (in my case 70 cm length tube)



1. Place the tube is closest to possible to the microphone and start recording with possible highest sampling rate (in my case 19200 samples),

2. Make sound by clapping hands or whistling,

3. With the sound editor find the first sound and its echo then measure time difference between them. The speed of sound could be calculated from below formula: speed = (2 * length of tube) / time. If you use difference in samples you could get time value by dividing this difference by sampling rate e.g. 750 / 192000.


At the of the measurement the speed of sound should be around 350 m/s relative to air temperature.


Below there is video with sample calculation of sound speed with usage of Audacity editor: