Science of Sound and Music

How can we measure the speed of something?

How can we measure the speed of something?

Distance ÷ Time = Speed

How can we measure the speed of something?

Distance ÷ Time = Speed

Some examples of “speed”…

Snail: 2 inches per hourCar: 55 miles per hourLight: 300,000,000 meters per second

How can we measure the speed of something?

Distance ÷ Time = SpeedIn 1998 Florence Griffith-Joyner set the World Record in the women’s 100 meters by running it in 10.49 seconds.

What was her speed?

How can we measure the speed of something?

Distance ÷ Time = SpeedIn 1998 Florence Griffith-Joyner set the World Record in the women’s 100 meters by running it in 10.49 seconds.

What was her speed?

100 meters ÷ 10.49 seconds = 9.53 meters per second

Temp (deg C) Speed (m/s)

20 343.2

21 343.78

22 344.36

23 344.94

24 345.52

25 346.1

The speed of sound varies slightly with temperature…..

Temp (deg C) Speed (m/s)

20 343.2

21 343.78

22 344.36

23 344.94

24 345.52

25 346.1

Distance ÷ Time = Speed

The speed of sound varies slightly with temperature…..

Setup and procedure

• Connect microphone preamps to “Line In” jack on PC via RCA to 1/8” stereo cable

• Open Audacity– Under the “Edit > Preferences” menu, set Channels to

2 (Stereo)

• Set PC to record from “Line In”– Open “Volume Control”

• Press record on Audacity• Make a loud sharp noise (eg. snap fingers)• Press stop on Audacity

General notes on the experiment

• The microphone converts sound to electricity.• The amplifier is used to increase the

microphone's low output voltage to a stronger level that can be recorded by the PC.

• The PC is capable of recording in stereo, which means it can simultaneously record the signals from two different microphones.

General notes on the experiment

• Sound from a source will travel across the room and reach the microphones at different times.

• The recorded audio can be analyzed on the PC to determine the amount of time it took for sound to pass from the location of mic 1 to mic 2.

• The distance between the microphones can be measured with a ruler, tape measure, etc.

• The speed of sound can be calculated by dividing the distance by the time.

Microphones placed 143 ½ inches apart 345.3 m/s

Example screen shot