MUSICAL ACOUSTICS

WAVES

Science of Sound, Chapter 3

WAVE PROPERTIES:•Reflection•Refraction•Interference•Diffraction•Doppler Shift

WHAT IS A WAVE?

Waves are disturbances that transport energy and information through a medium (but the medium itself is not transported).

Waves can be longitudinal (e.g. sound waves) or transverse (e.g. waves on a string or water waves).

ttp://www.animations.physics.unsw.edu.au/ //www.avnimations.physics.unsw.edu.au/

Traveling wave on a rope

Reflection of a pulse:

at a fixed end

at a free end

Mirror image of an impulsive wave approaching:

A plane mirror (left)

A corner mirror (right)

REFLECTION OF AN IMPULSIVE WAVE

At a fixed end At a free end

SUPERPOSITION OF WAVE PULSES

INTEFERENCE OF TWO IDENTICAL WAVES ON A STRING

At times t1 and t5 there is constructive interference;

at time t3 there is destructive interference.

Note that at points marked N, the displacement is always zero; this represents a STANDING WAVE

REFLECTION OF PRESSURE (SOUND) PULSE

SPEED OF SOUND IN IDEAL GAS

OCEAN WAVES

WHEN THE WAVE ENTERS SHALLOW WATER IT SLOWS DOWN AND ITS HEIGHT INCREASES

DOPPLER EFFECT

REFLECTION – WATER WAVES

REFLECTION – SOUND WAVES

REFRACTION

REFRACTIONTWO MEDIUMS

REFRACTION THROUGHA PRISM

ANGLE OF INCIDENCE

IMAGES FORMATIONBY LENSES

REFRACTION OF LIGHTBY WATER

REFLECTION

REFRACTION

INTERFERENCE OF WAVES FROM TWO IDENTICAL SOURCES

INTERFERENCE OF WATER

WAVES

DIFFRACTION OF WATER

WAVES BY A SLIT

DIFFRACTION

DIFFRACTION OF LIGHT BY A PIN

DIFFRACTION OF LIGHT BY

A SCREW

DIFFRACTION OF LIGHT BY

A RAZOR BLADE

DIFFRACTION BY A SINGLE

SLIT

DIFFRACTION

DIFFRACTION OF WATER WAVES

DIFFRACTION OF LIGHT AND SOUND WAVES

SPECTRAL ENERGY DISTRIBUTION OF A WHITE LED

LED SPECTRAL RESPONSE CURVE