Building Utilities 3 - Week 1 PDF

BUILDING UTILITIES 3 ARCHITECTURAL ACOUSTICS and LIGHTING WEEK 1  ACOUSTICS the science of sound and vibration which refers to the stress fluctuations as well as waves in a material medium. the art and science of designing a room or building which insures both comfort and c...

BUILDING UTILITIES 3 ARCHITECTURAL ACOUSTICS and LIGHTING WEEK 1  ACOUSTICS the science of sound and vibration which refers to the stress fluctuations as well as waves in a material medium. the art and science of designing a room or building which insures both comfort and communication, and provides special features as the purpose and use of the structure requires. the science of sound phenomena in buildings dealing with the production, transmission, and absorption of sound in order to secure the distinct conditions in every part of the building or room. ❖ All acoustic situations have three common elements: o SOURCE - can be made louder or more quiet o TRANSMISSION PATH - the path can be made to transmit more or less sound o RECEIVER - the listener; assumed to have a pair of healthy young ears with a detection range of 20 to 20,000 Hz. TYPES OF ACOUSTICS ❖PHSYCO ACOUSTICS - deals with the reaction of human beings to audible sound ❖ENVIRONMENTAL ACOUSTICS - deals with the effects of the environment upon audible sound waves ✓ ARCHITECTURAL ACOUSTICS / ROOM ACOUSTICS - may be defined as the technology of designing spaces, structures, and mechanical systems to meet hearing needs. ✓ LANDSCAPE ACOUSTICS ❖ELECTRO ACOUSTICS - deals with the generation and detection of audible sound waves ❖SONICS - deals with the technical application of mechanical waves in basic scientific research, industry, and medicine.  SOUND Is a physical wave, or a mechanical vibration, or simply a series of pressure variations in an elastic medium. For airborne sound – the medium is air For Structure-borne sound – the media are concrete, steel, wood, glass and a combination of all of these Any vibratory motion of bodies, the transmission of these vibrations in a medium, and the sensation produced on the human auditory mechanism An alteration in pressure (particle displacement in velocity) projected and propagated in an elastic material Also, Audible signals ❖ SOURCES OF SOUND SPEECH –produced by human voice MUSIC –produced by an instrument NOISE – produced by impact, by vibrating bodies, even by speech or music SOUND TYPES OF SOUND  WANTED – sound heard as perfectly as possible at the right level or loudness without pain or strain  UNWANTED – sound which entails an annoyance factor PROPERTIES OF SOUND  Sound must always have a source, a path, and a receiver.  SPEED - sound travels at 1130 ft. per second. Or 344 meters per second at normal room temperature (68°F) - sound travels faster in denser media  INTENSITY - rate at which sound energy is being transmitted  - intensity diminishes inversely as the square of the distance ◼ Decibel – the unit which sound intensity is defined for architectural purposes ◼ Decibel-meter – instrument by which sound intensity is measured ❖ SOUND PROPERTIES OF SOUND  SOUND PRESSURE - the fluctuation in the atmospheric pressure caused by the vibration of air particles due to sound wave  WAVELENGTH - the distance a sound wave travels during each complete cycle of vibration measured in meters or feet  LOUDNESS - subjective attribute of an auditory sensation in terms of which sound may be ordered on a scale of soft to loud   THRESHOLD OF AUDIBILITY - minimum intensity that is capable of evoking an auditory sensation in the ear  THRESHOLD OF PAIN - minimum sound pressure level which stimulates the ear to a point which is painful SOUND PROPERTIES OF SOUND  FREQUENCY - the number of displacements or oscillations that a particle undergoes in one (1) second ◼ HERTZ – unit measure of frequency; numerically equal to cycles per second ◼ PITCH - the attribute of an auditory system which enables us to pinpoint sounds on a scale extending from hight o low frequency - subjective response of human hearing to sound frequency ◼ TONE - sound sensation having pitch ◼ DIRECTIONALITY OF SOUND SOURCES o the way in which it sound is distributed in a region free from reflecting surfaces o sound sources radiate sound waves in all directions; o radiation pattern varies with the frequency o high frequency sounds are more pronounced along the longitudinal axis of the sound source. SOUND NATURAL ELEMENTS THAT AFFECT SOUND  TEMPERATURE - particles of sound tend to follow cold air  CLOUDS - if heavy, clouds can act as a reflecting surface  WIND - may change the direction of sound  BODIES OF WATER - can also act as a reflecting surface CHARACTERISTICS OF SOUND ¤ SOUND REFLECTION – sound reflected off a surface, usually one which is hard, rigid and / or flat ◼ FLAT SURFACE – uniform reflection ◼ CONVEX SURFACE – sound dispersion ◼ CONCAVE SURFACE – sound concentration As a sound wave strikes an interface between two media withnormalincidence (i.eorthogonal or perpendicular to the direction of the wave) sound can only either bereflectedor transmitted SOUND REFLECTION CONVEXSURFACE –sound dispersion FLAT SURFACE –uniform reflection CONCAVESURFACE –sound concentration SOUND CHARACTERISTICS OF SOUND  SOUND ABSORPTION - sound waves absorbed into a material upon contact  - change of sound energy into some other form  SOUND DIFFUSION- occurs when sound waves are dispersed equally in a room  SOUND DIFFRACTION - acoustical phenomenon which causes sound waves to be bent or scattered around such obstacles as corners, columns, walls, beams, etc. SOUND DIFFRACTION SOUND DIFFRACTION SOUND DIFFRACTION SOUND DIFFRACTION SOUND CHARACTERISTICS OF SOUND ¤ SOUND REFRACTION - change of sound wave direction as it moves from one medium to another of different density ¨ SOUND CHARACTERISTICS OF SOUND ¤ SOUND TRANSMISSION -sound which penetrates through surface 1. INCIDENT or DIRECT SOUND 2. REFLECTED SOUND 3. SOUND ABSORBED BY SURFACE TREATMENT 4. DIFFUSED SOUND 5. DIFFRACTED SOUND 6. TRANSMITTED SOUND 7. SOUND DISSIPATED WITHIN THE STRUCTURE 8. SOUND CONDUCTED BY THE STRUCTURE