Sound

Learning objectives:

• Understand the difference between longitudinal and transverse waves
• Know that frequency is measured in units called Hertz, which is abbreviated Hz, which represents the number of cycles/second.
• Know that humans can hear frequencies from about 20 Hz to 20,000 Hz.
• Understand that the amplitude of a sound wave determines how loud it is.
• Understand that the frequency of a sound wave determines the pitch.

Longitudinal vs. Transverse Waves

• Waves can be thought of as traveling along a line away from the source of the waves.
• In a transverse wave, the oscillation is at a right angle to the direction the wave is traveling.
• In a longitudinal wave, the oscillation is in line with the direction of the wave.

Examples of transverse waves include:

• A vibrating string
• Electromagnetic waves
• Water waves
• Some earthquake waves

Examples of longitudinal waves include:

• Sound waves
• Ripples in a slinky
• Some earthquake waves

A YouTube video of a slinky demonstrating longitudinal and transverse waves.

Resources:

In science club, we played with an app called Phyphox, which allows you to use the sensors on your phone to do multiple experiments.

The experiments that we did include:

• Looking at the wave pattern of our voices when we made different sounds, using “Audio Scope”.
• Looking at the major frequencies of our voices when we made different sounds, using “Audio Spectrum”.
• Looking at the musical pitch that our voices made, using “Audio Autocorrelation”.