The document outlines the physics of sound, describing sound as mechanical waves of pressure that transfer energy through matter. It explains different types of waves, their characteristics such as amplitude, pitch, and loudness, and introduces concepts like interference patterns and standing waves. Key attributes of sound are highlighted, including sonic texture and spatial location, emphasizing the cyclical nature of waves and their ability to interact with each other.

1. PHYSICS OF SOUND

2. SOUND
• An oscillation through matter
• A transfer of energy
• Takes the form of a mechanical wave
of pressure and displacement
• Moves outward from the point of
origin
• Sounds can interact with other
sound and objects (reflectivity,
interference, refraction)

3. WHAT IS A WAVE?
Waves move over long distances – the movement
of the material it passes through is limited.
What we ‘see’ when we see a wave is the energy
moving through matter.
To create a wave, there needs to be some initial
energy input.

4. TYPES OF WAVES
• Longitudinal wave
• along direction of
motion
• Transverse wave
• at right-angle to direction
of motion
• Surface wave

5. SOUNDWAVES

6. MECHANICAL WAVES
• Also known as pressure or compression waves
• Energy propagates in the same direction as the wave
𝐴 𝑥, 𝑡 = 𝐴0 cos(𝑘𝑥 − 𝜔𝑡 + 𝜙)
𝐸 ∝ 𝐴2
𝑘 =
2𝜋
𝜆
𝜔 = 2𝜋𝑓
𝑣 = 𝑓𝜆 =
𝜆
𝑇
=
𝑑𝑖𝑠𝑡𝑎𝑛𝑐𝑒
𝑡𝑖𝑚𝑒

7. CHARACTERISTICS OF WAVES
Amplitude – 𝐴0
how tall the wave is from its point of
equilibrium to its peak.
Angular frequency – 𝜔
the time it takes to go through a whole wave
cycle, trough to trough or peak to peak.
Sound pressure / Intensity – 𝐼0
sound power per unit area.
𝐿1 = 10 log10
𝐼
𝐼0
𝑑𝐵
𝐼 𝑟 ∝
1
𝑟2
Wave number – 𝑘
The higher this number is,
the higher this pitch will
be.

8. CHARACTERISTICS OF SOUND
• Pitch – how “high” or “low”
• Duration – how “long” or “short”
• Loudness – how “loud” or “soft”
• Timbre – the perceived quality of the sound. A guitar as opposed to a piano or thud
of a falling rock or a mechanical drill.
• Sonic Texture – the number of sound sources and the interaction between them. A
quartet as opposed to an orchestra.
• Spatial Location – the distance and location of the sound source.

9. INTERFERENCE PATTERNS
• When waves overlap, they add and subtract.

10. STANDING WAVES
• A phenomena that is caused by waves being reflected back and forth inside of a
medium at specific frequencies or two waves traveling in opposite directions.

11. STANDING WAVES

12. SUMMARY
• Waves are cyclical.
• Waves can be described by a few simple values, mostly: 𝐴, 𝑓, 𝜆, and 𝑣.
• Waves move away from the point of origin radially and lose power by 1/𝑟2
• Waves can add together or subtract from each other, based off their amplitude.
• Standing waves form from interference
Contact
Blake Nicholson