Acoustics-mod1-aswin Hrishikesh.pptx

ACOUSTICS: •Science of sound – Production, Transmission and its effects including biological and

psychological effects.

•CAUSE: Natural or Artificial. •TRANSDUCTION: Convert energy from some other form into sonic energy, producing a sound wave. •PROPAGATION: The wave carries energy throughout the propagating medium. •EFFECT: May be purely physical or it may reach far into the biological or volitional domains.

ARCHITECT’S ROLE:

Source slight

Path major design influence

Receiver primarily interested

INTENSITY: •Sound intensity or acoustic intensity is defined as the sound power per unit area.

•P is the sound power •A is the area •The SI unit of sound intensity is the watt per square metre (W/m2).

•For a spherical sound wave: •the intensity in the radial direction as a function of distance r from the centre of the sphere is given by

•P is the sound power •A(r) is the area of a sphere of radius r •This relationship is an inverse-square law.

SOUND PRESSURE: •Sound pressure or acoustic pressure is the local pressure deviation from the ambient (average, or equilibrium) atmospheric pressure, caused by a sound wave. •The SI unit of sound pressure is the Pascal (Pa). •Sound pressure of a spherical sound wave decreases as 1/r from the centre of the

sphere.

•Inverse Proportional Law.

1. silence;

2. audible sound; 3. atmospheric pressure; 4. sound pressure

•The radiated sound power (sound intensity) is the cause and the sound pressure is the effect.