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Acoustics: sound


Acoustics is classically divided into sound and vibration. Sound refers to waveforms traveling through a fluid medium such as air, while ... – PowerPoint PPT presentation

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Title: Acoustics: sound

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

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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.

  • 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.

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

Sound Waves amplitude frequency (cycles)
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

  • 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

  • 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.

  • 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.

an example of books dedicated to the study of
architecture and acoustics
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.

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

  • 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

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.

  • 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

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."

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

'Stradia' sound simulation program
  • 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

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