Velocity of Sound Apparatus – Speed of Sound & Standing Waves

The Velocity of Sound Apparatus is a dual-purpose physics teaching instrument designed to measure the speed of sound in air and investigate standing wave behaviour.

Using an audio signal generator and a dual-beam oscilloscope, students can analyse the relationship between frequency, wavelength and the velocity of sound. The apparatus uses signals from a loudspeaker and microphone to demonstrate phase differences as sound travels through air.

Key Features

• Measures the velocity of sound in air
• Demonstrates standing waves, nodes and antinodes
• Uses loudspeaker and microphone signals for phase comparison
• Supports oscilloscope-based waveform analysis
• Includes a reflector for standing wave investigations
• Compact apparatus for school and tertiary physics laboratories

How It Works

Measuring the Speed of Sound

An audio signal generator drives the loudspeaker, producing a sound wave of known frequency. The loudspeaker and microphone signals are compared using a dual-beam oscilloscope.

By observing the distance corresponding to a complete 360° phase shift, students can determine the wavelength and calculate the velocity of sound using:

Velocity = Frequency × Wavelength (v = f × λ)

Investigating Standing Waves

With the reflector positioned in the apparatus, standing waves can be produced. Variations in the signal amplitude displayed on the oscilloscope allow students to identify nodes and antinodes and explore the behaviour of reflected sound waves.

Educational Applications

• Measuring the speed of sound in air
• Investigating frequency and wavelength
• Observing phase differences
• Exploring standing waves, nodes and antinodes
• Understanding sound reflection and wave interference
• Oscilloscope-based physics investigations

Additional Equipment Required

An audio signal generator and a dual-beam oscilloscope are required for operation and are not included with the apparatus.