Acoustics: sound

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Acoustics sound

• Sound is a mechanical wave and therefore requires
  a medium in which it can travel. Acoustics is
  classically divided into sound and vibration.
  Sound refers to waveforms traveling through a
  fluid medium such as air, while vibration
  describes energy transmitted through denser
  materials such as wood, steel, stone, dirt,
  drywall or anything besides a fluid. It is not
  heard as much as felt, due to its extremely low
  frequency, which is below the range of most human
  hearing.

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Wallace Clement Sabine

• In 1895 Wallace Clement Sabine 1868-1919 a
  physicist, was instructed by the Corporation of
  Harvard University to remedy acoustical
  difficulties in the lecture room of the Fogg Art
  Museum. Two years were spent experimenting in
  this room, and permanent changes were made.

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• About this time it became certain that a new
  Boston Music Hall would be erected. From there
  followed much to Sabine's surprise a vocation for
  a new branch of physics architectural acoustics.
  
• Sabine was the first to bring quantitative
  measures to bear on reverberation, absorption,
  and sound transmittance.

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• Sound travels significantly more slowly than
  light (331.45 m/s versus 299,792,458 m/s),

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Sound Waves amplitude frequency (cycles)
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an Owens-Corning product called 'Soundsoak'

• Soundsoak acoustical wall panels are a complete
  line of ready-to-install vinyl- or fabric-wrapped
  acoustical panels designed to provide sound
  absorption and tackable surfaces. They're
  available in convenient, cost-effective sizes.

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advanced study of acoustics

• Acoustics is the subject of formal, advanced
  study, including the fields of engineering,
  architecture, and psychology.
• For example, the School of Architecture at
  Rensselaer Polytechnic Institute offers a formal
  program for a Masters of Science degree in
  Building Science (Concentration in Architectural
  Acoustics)

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• The Graduate Program in Architectural Acoustics
  offers an intense curriculum in acoustics for
  effectively shaping sonic environments to achieve
  optimum acoustic performance and sound quality.
  The Program offers studies toward both Master of
  Science and Ph.D. degrees. Further doctoral
  degree studies offer a unique program in
  architectural acoustics, providing the knowledge
  for next-generation acousticians involved in room
  acoustics, psychoacoustics, acoustic and
  vibration measurement techniques, and sound
  reinforcement.

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• Researchers in the acoustics program in the
  School of Architecture are investigating how the
  design of a classroom can affect how easily
  students hear. The researchers believe that if
  more attention is paid to classroom acoustics
  when designing the space, students will have an
  easier time learning and understanding what's
  going on.

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• Research of this kind could lead to the
  development of new standards for classroom
  acoustics. Regulators for the Americans with
  Disabilities Act are currently working on such
  standards, which exist already in countries such
  as Germany and the United Kingdom.

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an example of books dedicated to the study of
architecture and acoustics
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Music and Drama Theatre Acoustics

• The acoustical characteristics of a venue for the
  live performance of music or drama are an
  important part of the audience experience. For
  music performance, the room becomes part of the
  instrument, helping define the character of the
  musical sound that the audience hears.

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Reverberation Time

• Reverberation time refers to the amount of time
  required for the sound field in a space to decay
  60dB, or to one millionth of the original power.
  In simple terms this refers to the amount of time
  it takes for sound energy to bounce around a room
  before being absorbed by the materials and air

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• Reverberation time is important because it can
  affect how well you understand speech, and it can
  change the way music sounds. The effect on speech
  intelligibility is noticeable in a gymnasium or
  arena, where you often can't understand someone
  who is only 10 or 15 feet away from you

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Useful Reflections

• Reflections are an important part of acoustical
  design for music performance venues. For
  effective musical acoustics, the reflections have
  to arrive within the correct time window, and
  from the correct direction.

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• The reflections help to boost the level of
  acoustic instruments and human voices in the
  audience area. They also influence timbre and
  help define the apparent size or perspective of
  the instruments. The critical time interval we're
  talking about is a very brief 0.3 seconds

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• Actual sound can be synthesized based on data of
  the layout and materials of halls, both existing
  and still in the design stage

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Acoustics Consultantsmay provide

• Architectural Acoustics
• Sound Isolation Testing
• Impact Isolation Testing
• Mechanical (HVAC) System Noise and Vibration
• Environmental/Community Noise Assesment
• Computer Physical Acoustical Modeling
• Field Testing
• Industrial Noise Control
• Sound Masking Systems Desig

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• A properly designed acoustical environment
  provides a good listening experience for the
  audience by enhancing the performance or
  presentation. Even and natural sound coverage,
  freedom from intruding noise and a sense of
  presence from the performer or presenter are
  all-important aspects of "good acoustics."

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• Acoustics should be considered very early in the
  design process and the aesthetic concept
  developed in accordance with those requirements

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'Stradia' sound simulation program
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• This is a system in which the acoustics of a
  completed hall can be actually experienced at the
  design stage. Sound is synthesized based on the
  layout of the hall and other data, and acoustics
  can be designed that can actually be confirmed by
  ear.

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Sound ray diagram of New National Theatre, Tokyo
(May 1986
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