Angle of reflection (Architectural Acoustics)

REFLECTION

OF SOUND

When a “free” sound wave (one free from the influence of reflective surfaces) strikes a uniform surface that is large compared to the wavelength of sound, the reflection of the wave is similar to the familiar reflection of light.

-In acoustics, reflection causes echoes and is used in sonar. -Common examples include the reflection of light, sound and water waves. -Sound is reflected from a surface at the same angle at which it strikes the surface. This fact makes it possible to focus sound by means of curved reflecting surfaces in the same way that curved mirrors can be used to focus light.

ANGLE OF REFLECTION & ANGLE OF INCIDENCE

The angle formed by a reflected ray and a perpendicular to the surface at the point of reflection.

The angle formed by a ray or wave incident on a surface and a line perpendicular to the surface at the point of incidence.

Law of reflection“for specular reflection the angle at which the wave is incident on the surface equals the angle at which it is reflected”

The loudness of reflected sound is always less than direct sound

The combination of direct sound & reflected sound results in loudness that is greater than direct sound alone.

MATERIALS POROUS MATERIALS will absorb

some energy ROUGH MATERIALS (where rough is

relative to the wavelength) tend to reflect in many directions—to scatter the energy, rather than to reflect it coherently.

Sound Boards: Curved surfaces can reflect sound waves.

draperies or acoustical tile = sound-absorbing materials

Clothing also absorbs sound

CREEP This describes the reflection of sound along a

curved surface from a source near the surface. Although the sound can be heard at points along the surface. It is inaudible away from the surface.