BU3 Module 1 and 2A

• Acoustics


  The science of sound and vibration which refers to stress fluctuations as well as waves in a material medium
• Acoustics


  The art and science of designing room or building which ensures both comfort and communication and provides special features as the purpose and use of the structure requires
• Acoustics


  The science of sound phenomena in buildings dealing with the production, transmission, and absorption of sound in order to secure distinct conditions in every part of the building or room
• Acoustics system


  Exact science and practical art concerned with the production, control, transmission, reception, and effects of sound in an enclosed space
• Acoustics system (within the context of architecture)


  Adequately plan a space to reinforced needed sound to eliminate unwanted sound, and to prevent transmission of unwanted sound
• Scope of acoustics


  • Psycho acoustics
  • Environmental acoustics
  • Architectural acoustics
  • Landscape acoustics
  • Electro acoustics
  • Sonics
• Sound


  A physical wave, or mechanical vibration, or simply a series of pressure variations in an elastic medium
• Types of sound


  • Speech
  • Music
  • Noise
  • Background noise
  • White noise
• Sources of sound


  • Vibrating bodies
  • Impacts
  • Speech
  • Music
• Sound pressure waves


  Alterations in pressure (particle displacement in velocity) projected and propagated in an elastic material
• Pitch


  The quality of sound governed by the rate of vibrations producing it
• Loudness


  An attribute for a sound that places perception on a scale ranging from inaudible/quiet to loud/uncomfortable, in response to change in sound pressure level
• Period (T)


  The time required for one wavelength to pass a certain point
• Wavelength


  The distance between similar points on successive waves or the distance the sound travels in one cycle of vibration
• Frequency (f)


  The number of cycles of compression and rarefaction of air makes in given unit of time or one second
• Speed (c)

  The speed of sound in air: 343 m/s (1,130 ft/s)
• Intensity


  The amount of sound power falling on/passing through/crossing a unit area
• Decibel (dB)


  A logarithmic unit used to measure sound level
• Sound pressure level of common environmental sounds

  • Whisper
  • Normal conversation
  • Busy traffic
  • Jackhammer
  • Jet engine
• To be heard by an observer, a sound wave must have a certain minimum pressure value
• Minimum possessing inertia and elasticity is needed to propagate a physical disturbance detected by a normal ear (Sound waves do not travel through a vacuum)
• Auditory sensation produced by sound will be called sound sensation
• Sound has its own origin in vibrating bodies
• Change in pressure, density, and temperature due to passage of sound wave through air are extremely small
• Sound travels much faster in liquids and solids than it does in air
• Reverberation


  The persistence of sound after the source of sound has stopped
• Echoes


  A sound wave reflected or returned with sufficient magnitude and delay so as to be perceived as a sound distinct from the directly transmitted sound
• Dead room


  A room characterized by large amount of sound absorption
• Live room


  A room characterized by small amount of sound absorption
• Creep room


  A reflection of a sound along a curved surface
• Velocity of sound


  The rate of flow of sound energy through a unit area at that point, the unit area being perpendicular to the specified direction
• Sound absorption


  The interception and conversion of sound energy into other form of energy by the structure of material
• Absorption coefficient (α)


  Ia/Ii, where Ii = intensity impinging on the material, watts/cm2; Ia = intensity absorbed by the materials, watts/cm2
• Total absorption (A)


  Sα, where S = surface area, square feet; α = coefficient of absorption
• Sabin


  Unit of sound absorption (One square feet of a perfectly absorptive material)
• Most common materials do not absorbed all sound energy
• Reflection


  The return of sound wave from a surface
• Diffusion


  The scattering or random redistribution of a sound wave from a surface
• Reflection of sound on different surfaces

  • Reflective
  • Absorptive
• Reverberation


  The persistence of sound within an enclosed space, caused by multiple reflections of the sound after its source stopped