Physics of Sound Waves

Sound and Wave Model

• Sound is defined as vibrations that travel through the air or another medium and can be heard when they reach a person's or animal's ear.

Characteristics of Sound

• Sound travels in waves through objects or air.
• Acoustic refers to the properties or qualities of a room or building that determine how sound is transmitted in it.
• Acoustic also refers to the branch of physics concerned with the properties of sound.

Production and Transmission of Sound

• Sound is produced by a vibration and travels as a longitudinal wave.
• Sound travels through air by making air molecules vibrate.
• The vibrations are picked up by the ear and sent to the brain as a message.

The Ear

• Sound waves are collected by the ear lobe or pinna.
• The waves travel along the ear canal and make the ear drum vibrate.
• The vibrations are amplified by the small bones (ossicles) and converted into electrical signals by the cochlea.
• The auditory nerve takes the signals to the brain.

Independent Task 1: Quiz

• Sound can pass through water, but not through space.
• A human can hear sounds up to 20 kHz, not 30 kHz.

Signal Generators and Oscilloscopes

• Signal generators can produce signals over a range of frequencies and varying amplitudes.
• Oscilloscopes allow us to study the frequency and loudness of a sound.

Pitch (or Frequency)

• The shorter the wavelength of the wave, the higher the frequency of the sound.
• The more waves you see, the higher the pitch/frequency.
• The highest pitched sound has the shortest wavelength/most number of waves visible.

Loudness

• The larger the amplitude of the wave, the louder the sound.
• The bigger the wave you can see, the louder the sound.
• The loudest sound has the largest amplitude.

Oscilloscope Traces

• The amplitude of the wave is the distance from the horizontal line to the peak of each curve.
• The larger the amplitude, the more energy a wave has.