ACOUSTICS & LIGHTING

incandescent

stimulating effect, conducive to drinking, induces sleep. Best for bars and nightclubs

fluorescent

emits a light similar to daylight, conducive to eating, reading, studying, etc.

photometry

the science that deals with the measurement of light

candle power

refers to the unit of intensity of light of one standard candle whose light is concentrated at a point and the light source is assumed to be placed at the center of a hollow sphere of one foot radius

candle power

the illumination at any point on the sphere is one foot candle (abbreviated ft-s), the unit for the power or intensity of light.

standard candle

is the brightness of a black body at the temperature of freezing platinum

lumen (abbreviated L)

-is the unit of luminous flux, amount f light falling on a surface from the source

one-foot

When 1 lumen of flux is uniformly distributed over 1 square foot of area, the illumination at any point on the area is_____candle

Illumination (E) = I / D2

I = the candle power of the source D=the distance from the source in feet

FORMULA FOR ILLUMINATION

diffusion

light rays leaving the source strike a rough, opaque surface which spreads the light in various directions

diffusion

in addition, light is broken up while in reflection, the light bounces back at a different direction

polarization

light ray striking a polarized glass causes the illumination of the horizontal light rays and allows the vertical rays to penetrate the glass (resulting in soft lighting)

transmission

-light rays strike a plain (surface) transparent glass which allows the rays to proceed farther

reflection

-light striking a silvered surface is reflected back with no diffusion and the angle of incidence is equal to the angle of deflection

refraction

-light rays striking a clear glass placed at an angle with respect to the rays are reflected at an angle within the glass and continues at another angle on the far side of the glass

CANDLE POWER DISTRIBUTION CURVE

Is a graphic representation of the distribution of light intensity of a luminaries (container of a source light). Those at the center of the sphere receives more light than at the edges

ACOUSTICS

is a branch of science that deals with the control and propagation of sound.

sound

originates from a vibrating body. It is pressure have in an elastic medium. It is not restricted, it spreads outward from its source in all directions diminishing in intensity inversely as the square of the distance from the source increases

sound

these vibrations from the body come outward as compressions and rarefactions in the surrounding air

rarefaction

the instantaneous, local reduction in density of a gas resulting from passage of a sound wave , or the region in which the density is reduced at some instant

rarefaction

elongation of sound

Frequencies

the vibration from a body are called _________

frequencies

cycles per second (cps) or vibrations per second

Sound waves

(vps) and the compressions and rarefactions are called __________

SOUND

is a physical wave or simply a series of pressure vibrations

air

- for airborne sound, the medium is ______

building materials

for structure borne sound, the medium is ________________

20 to 20,000 Hz

it is always assumed that the hearer has a pair of healthy young ears with the direction range of ______________

1125 ft/sec at 20ºF

speed of velocity

1ft/sec for every 10º

the velocity increases ________________ rise in temperature (in Fahrenheit)

formula for velocity

frequency

is the number of cycles of vibrations executed per second.

40 vps to 16,000 vps

Humans can hear sounds within the ______________ range

masking of sound

a sound maybe covered up or absorbed by another sound.

soporific effect

that effect brought about by a low-steady sound

WAVELENGHT

distance between two crests of a sound wave

low, high

_____ frequency sounds have longer wavelengths than _______ frequency sounds.

WAVELENGHT

the distance traveled by sound in one second divided by the frequency of the wave

100 cycle

the wavelength of a ______ wave is a little of eleven feet long and a five hundred cycle wave

WL

distance traveled by sound wave in one second / the frequency of the wave

sound wave

When a___________ in a room strikes a surface in a room, part of the energy is reflected, part is absorbed by the surface and part is transmitted to the surface

rigid, flat and smooth

A surface that is __________ usually reflects sound.

“diffraction of sound”

One characteristic of sound is that, like light, it can bend around an obstruction known as __________________

Low, high

_____ frequency sounds are diffracted more easily than ________ frequency sounds

direct or original sound

from the source and directly delivered to the hearer

reflected sound

from all directions of the room

0.05 of a second, 57 ft

for a sound to be heard by a listener comfortably, the reflected sound must come to him not later than _______________ or in terms of distance, the direct sound and the path of the reflected sound should not exceed _________

TRUELALU

Sound travels much faster in liquids and solids than it does on air. (True or False)

PAKEEEEE

sound travels much faster than the speed of light. (Reyal or Pake)

echoes and reverberations

As sound travels much slower than the speed of light, the resulting defects in many rooms are ________________

0.058 seconds

When the reflected sound, which reaches an observer, is delayed more than about _____________ relative to the direct sounds, they are distinguished as echoes.

Reverberation

consist of successive reflections of sounds in a room, and since sound travels only about 1130 ft or 344 m/sec

RESONANCE

Is what happens to a body when another vibrating body vibrates and initiates. The other body to vibrate in harmony with it

True

Low frequencies have more resonance than the high frequencies because low frequencies have longer wavelengths and therefore more multipliers to the dimensions of the room than high frequencies. True or False

SOUND ABSORPTION

The sound phenomenon that happens to sound when it strikes a surface is that the sound is absorbed by the surface.

heat energy

when sound wave strikes an absorbent surface, the sound waves through friction on the pores of the surface are transformed into ___________

soft and porous surfaces

such as corkboard, foam or Styrofoam or any material which has this property like draperies on the walls and carpets on the floor

panel absorber

consisting of two layers of materials with an airspace between them. The outer layer, being of porous type and the inner layer of solid background

cavity resonator

- Consisting of an enclosed body of air which is connected by a narrow passage with the space containing the sound waves.

direct sound

When the sound wave is transformed into heat energy, the sound will no longer be reflected. The sound heard is only the __________

sabin

This sound absorption efficiency of a material is measured in terms of units known as sabins, in which one ___________ means perfect absorption and 0 means no absorption

DECIBEL

measurement of the intensity of sound - abbreviated (db)

40db

limit for comfortable hearing

100-120 db

can no longer be comfortable, that is painful to the ear

ECHO

reflected

REVERBERATION

is a series of echoes coming from the same source

REVERBERATION TIME

is the time in seconds that a reflected sound diminishes for the case by 60db after the original sound has stopped

REVERBERATION TIME FORMULA

TRANSIENT SOUND

is the term applied to the direct sound which if the originating body stops, vibrating also stops.

DIFFUSION

When the reflections are so large that the sound level becomes uniform throughout the room. (no acoustical shadow)

near field

enerally within one wavelength of the lowest frequency of sound produced by the source.

3.30mts or 11 ft

the maximum wavelength for the male human voice is __________________

reverberant field

near large obstructions such as walls - is dominant and approaches a diffused condition

free field

exist between the near and reverberant field - the intensity varies as pressure squared and inversely with the distance

INVERSE SQUARE LAW

States that the intensity of sound is inversely proportional to distance from the source.

regular pattern

in an ordered sound, the instantaneous pressure follows a ____________

disordered sound

in a ___________________, the peak of acoustic power occur more or less at random, the periodic qualities of ordered sound are lacking

noise

unwanted sound

music

generally not always made up of ordered sound

speech

consists of both ordered and disordered sound

Cheering

during a basketball game heightens emotions and develops a sense of group unity

Jazz and classical music

generally provides a feeling of relaxation

Noise

from the rush hour traffic causes anxiety and tension

from the rush hour traffic causes anxiety and tension

Music makes a powerful impact on the senses. Often touching feelings too deep or too difficult to express in words.

The response approach

focuses on the therapeutic power of music heard from an external source and the body and minds reaction to such music.

The expression approach

identifies music’s power to come not only form its reception but also from its creation.

The source of the sound should be located ________ than any head in the audience.

140º

Because speech is directional, in plan, the seats should be positioned so that none falls outside an angle of ___________ the sound intensity will decay rapidly.

reflectors

In order for the direct sound to be reinforced by the reverberant sound, ________ should be used and angled towards that part of the audience farthest from the speaker.

50ft

The reflected paths should not exceed _____ more than the direct sound path.

CLOUDS

pieces of cloth hung on the ceiling to absorb sound not less than 2 ft in depth; 2 ft because the wavelength of low frequency sound is usually 2 ft

omnidirectional microphone

equally sensitive sound to sounds arriving at it from any direction

directional microphone

receives sound from one direction. For speaking purposes, the directional microphone is better to use because it reduces the feedback

LOUDSPEAKER

to give natural as much as possible as well as to make the sound louder

LOUDSPEAKER

diffuses low frequency sounds, projects directionally high frequency sounds

The high-level system

- which consists of a single loudspeaker with a high level of sound. This is most applicable for rooms with good acoustics

Low-level system

consists of several loudspeaker placed at strategic locations in the room and operating at low volume of sound. This is most useful for rooms with bad acoustic like churches and cathedrals

noise

an unwanted sound

sound insulation

a process or method of making a room invulnerable against the entry of noise

noise control

process of elimination or limiting the propagation of noise