Sound Science: DO YOU HEAR WHAT I HEAR?

What is sound? How does it relate to music?

Sound is a wave.

Waves carry energy through a medium.The medium is what the wave is moving through.For sound, the medium is usually air, but soundalso travels through solids such as steel andliquids such as water.

Sound is vibrations.

When a stringed instrument isplucked, the string moves up anddown in opposite directions from Its rest position, causing vibrations In the string.

The actual motion of the vibration,like the plucked string of an ‘ud, is called simple harmonic motion.

‘Ud (plucked lute) from Syria

Waves

Vibration results in waves: water waves, light waves,

sound waves, etc.

Sound waves (longitudinal waves), like all waves, Have four basic properties:

AmplitudeWavelengthFrequencySpeed

Sound is a longitudinal wave.

Longitudinal waves are Pressure waves.

As the tuning fork vibrates,air gets pushed closertogether, then spreadsfarther apart. This makesareas of high and lowpressure as the waves

travelfrom the tuning fork.

Sound Waves

The same idea works with bells, gongs, chimes, triangles, etc.

Idiophones

These instruments are classified as idiophones,instruments in which the material of the

instrumentitself, typically when struck, is what vibrates.

Bala (gourd-resonated xylophone) from Guinea Music box from USA

More Idiophones

Kono (slit drum) from Sierra Leone

Triangle from Belgium

Saron (metallophone) from Indonesia

Even More Idiophones

Gongs from Indonesia

Gong from Thailand

Chordophones

What do you see that vibrates oneach of these instruments?

Keyed zithers from USA

Morin khuur (bowed spike lute) from Mongolia.

Chordophones

Strings do the vibrating inchordophones.

‘Ud (plucked lute) from EgyptNyckelharpa (keyed fiddle) from Sweden

Membranophones

In a membranophone,the vibration is from astretched skin.

Pandero (single-headed frame drum) from Chile

Membranophones

Taiko (double-headed barrel drum) from USA

Talking drums (double-headed hourglass drums) from Nigeria

Aerophones

In aerophones, it’s a columnof air that vibrates―hard tosee, but it sounds great!

Over-the-shoulder horns (valved horns) from USA

Rondador (raft flutes) from Ecuador

Aerophones

Feadóg stain (duct flute) from the UK

Kudu horns (side-blown trumpets) from South Africa

Musical jug from USA

Aerophones

There are several ways to start the column ofair vibrating.

Lips of the player (as in a clarín or trumpet)

Reed (saxophone or bagpipe)

Turbulence as air flows across the opening (sikus or organ pipe)

Corpophones

When a vibration oraction is produced by abody part (or parts), itsends off waves creating sound.

Hand Claps

Finger Snaps

Leg Slaps

Mouth Clicks

Foot Stomps

What do you know?

Sound is a wave.

In a musical instrument, generate sound.

With , the sound generator is a vibratingstretched string.

Sound travels differently through various ,such as through air, solids, and water.

Want to know more?

MIM has a large collection ofmusical instruments. Some Use electricity to generate or amplify sound.

In other lessons, you will learn about sound generationwith a group of instruments we classify as electrophones.

Electric guitar from Taiwan