The Science of Sound

What is Sound?

Questions to Ponder...

  • How does your instrument work?
  • Why does a tuba sound different than a piccolo?
  • How is it that you can recognize someone's voice even if you cannot see them?

Explore

  • Get together with a partner that plays a different instrument.
    • work together to create an explanation as to how each other's instrument works
    • describe ways in which they are similar (be prepared to demonstrate)
    • describe ways in which they are different (be prepared to demonstrate)

Chimes

  • Observe the image of the chimes
    • What do you notice about them?
  • If you wanted to play a low pitched note, what would you do? What about a high pitched noted?

Pitch and Frequency

Pitch

  • the highness or lowness of a sound

Frequency

  • the number of vibrations per second

What Determines the Frequency of a Vibrating Object?

  • Based on your observations of the chimes above, what do you think causes the different bars to have different frequencies and therefore different pitches?
  • How can you demonstrate this with other instruments?

How would the pitches of the different sized drums differ?

How do you tune a drum?

Conclusion...

  • The pitch and frequency of a sound is determined by...
    • the length of the material that is vibrating and how much tension is on the vibrating object.

Sound Travels in Waves

Two Kinds of Waves

  • The two main categories of waves are electromagnetic and mechanical. Electromagnetic waves, like radio waves and sunlight, can travel through empty space. Mechanical waves such as sound and earthquakes waves, need something to travel through, which we call a a medium.
  • We most often hear sounds through the medium of the air. The matter that makes up the air (which we call atoms and molecules) vibrate when they come into contact with other vibrating atoms and molecules.
  • Observe the images below:

Online Tone Generator

  • The number of vibrations per second is called Hertz (Hz)
  • Use this site to explore the frequency of different notes.

Does Everyone Hear the Same Way?

  • Believe it or not, your age has a lot to do with your hearing. Take this online test to see how old your ears are.

Resonance

  • What's that buzz? Play a scale on a saxophone near a snare drum. What do you sometimes notice?
  • When one object vibrating at the same natural frequency of a second object forces that second object into vibrational motion we call that resonance.
    • When else do you notice resonance?

Why Do We Need to Know the Science of Sound?

Tuning

When tuning your instrument, do not immediately start playing a note as soon as you hear the tuning note.

  • Listen - When given a tuning note, take several seconds to just listen to it and make sure you know what it sounds like.
  • Imagine - Try to reproduce the tuning note in your own head.
  • Hum - Hum the note a few seconds out loud while trying to match it.
  • Play - Play the note while trying to keep your your breath steady. Do not bend the note to match the pitch.
  • Adjust - Change the length of the vibrating object (or tension in the case of strings and percussion) to match the tuning note. For woodwinds, pull the mouthpiece out to make the pitch lower and push in to make it higher. For brass, adjust the slides in the same way. For strings and percussion, tighten to go higher and loosen to go lower.
  • Repeat - Do it all over again until you get it right. Try different octaves as well!

Use the Online Tone Generator to practice...