Introduction to Acoustics

Architectural Acoustics

is the art and

technique of designing spaces, structures

and mechanical systems to meet hearing

needs.

comfort and communications

The art and science of designing a room

or building that insures both ______-t and

________, and provide special

features as to purpose and use of the

building.

shape and material

To control echoes and to secure the best distribution of sound through the study

of the ______ of the room and the estimation of the amount of sound absorbing

_______ needed.

Source of sound, Medium or Transmission Path, Receiver

The nature of sound, in order to be heard, requires the following elements:

Source of Sound

is normally a vibrating body, which

converts some other form of energy into vibration. The

source can be made quieter.

transducer

is often used as a generic term for

devices used in converting some form of energy into

sound such as loudspeakers and microphones.

Transmission path

is any substance that allows the vibration to be transmitted in the form

of a wave motion. The transmission can be made to transmit more or less sound.

Airborne Sounds

sounds that are transmitted by air.

Structure borne Sounds

sounds that are transmitted through solid bodies.

Music, speech, noise

Types of Sound

Music

sounds organized to have

melody, rhythm, harmony and dynamics.

Speech

to express with the voice.

Music and Speech can be classified

as ordered sounds since they are

integrated.

Noise

sound, especially, of the loud

and harsh kind.

Sound waves

are longitudinal wave motion

with which sound energy travels through a

medium.

vibrations

Sound waves are mechanical, unlike

electromagnetic waves, they require

_______ of their medium’s molecules or

particles.

cycle, frequency, amplitude, period

Sound Waves

Cycle

full circuit by the particle.

Frequency

number of complete cycles

per second measured in Hertz (Hz).

Amplitude

maximum displacement of

a particle to either side of its normal

position during vibration.

Period

– the time required for one

complete vibration, measured in

seconds per cycle.

Hertz (Hz)

The sound frequency is its number of

vibrations in cycles per second, also known as

20 to 20,000 Hz

The approximate frequency range of a person’s

hearing is

Power (Intensity or Loudness)

a sound’s

intensity is its loudness or pressure against the

eardrum, measured in decibels (dB).