Thread Academy

Pitch and Loudness

Relating pitch to frequency and loudness to amplitude.

  • Define and explain Pitch and Loudness in your own words
  • Use key terms such as frequency accurately
  • Apply what you have learned to new examples and questions
  • Avoid the common mistakes learners make with this topic

This lesson focuses on Pitch and Loudness: relating pitch to frequency and loudness to amplitude.

Definition: Pitch and Loudness

Relating pitch to frequency and loudness to amplitude.

Key ideas

Pitch depends on frequency, loudness on amplitude

Fast vibrations give a high frequency and a high-pitched note; slow vibrations give a low pitch. Big vibrations (large amplitude) make loud sounds, small ones make quiet sounds. Human hearing spans roughly 20 Hz to 20,000 Hz, and it fades at the top end as we age.

Sounds are made by vibrations

Pluck a guitar string and it vibrates, pushing the air back and forth — that is what your ear detects as sound. The vibrating object can be a string, a drum skin, vocal cords or a loudspeaker cone. No vibration, no sound — it really is that simple.

Key term — frequency: The number of vibrations per second, measured in hertz (Hz); it sets the pitch.

Worked example: Pitch and Loudness

A sound has a frequency of 440 Hz. Is this describing the pitch or the loudness?

The pitch — hertz measures frequency, which determines pitch.

Answer: The pitch — hertz measures frequency, which determines pitch.

Common mistakes
  • Mixing up pitch and loudness Pitch comes from frequency (how fast the vibration is); loudness comes from amplitude (how big it is).
  • Thinking sound travels in space Sound needs a medium — with no particles in a vacuum, astronauts must use radios.

Practice

Tightening a guitar string raises the note. Why?
What does tightening do to the vibration rate?

A tighter string vibrates faster — higher frequency means a higher pitch.

What is vibrating when you hear a drum?
What did the stick hit?

The drum skin (membrane) vibrates and pushes the air back and forth.

Which is faster: sound in air or sound in steel? Give the approximate speeds.
Think about how tightly packed the particles are.

Steel is faster: about 5000 m/s in steel versus about 343 m/s in air.

Why can two astronauts on a spacewalk not talk to each other directly?
What does sound need to travel?

Space is a vacuum with no particles, so sound cannot travel between them — they use radios instead.

Quick check

Pitch and Loudness — quick check

Which of these best defines "frequency"?

The number of vibrations per second, measured in hertz (Hz); it sets the pitch.

A ship's sonar echo returns after 4 s. The speed of sound in water is 1500 m/s. How deep is the water?

Distance = 1500 × 4 ÷ 2 = 3000 m.
Key takeaways
  • Pitch and Loudness: relating pitch to frequency and loudness to amplitude.
  • Pitch depends on frequency, loudness on amplitude: Fast vibrations give a high frequency and a high-pitched note; slow vibrations give a low pitch.
  • amplitude: The size of a vibration; a bigger amplitude means a louder sound.
  • Watch out for: mixing up pitch and loudness
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