Acoustic transmission

<h2 id="in-musical-instrument-design">In musical instrument design</h2>
<p><a href="/facts/Musical_instrument/UMSjL1Ks">Musical instruments</a> are generally designed to radiate sound effectively. A high-impedance part of the instrument, such as a string, transmits vibrations through a bridge (intermediate impedance) to a sound board (lower impedance). The soundboard then moves the still lower-impedance air. Without bridge and soundboard, the instrument does not transmit enough sound to the air, and is too quiet to be performed with. An electric guitar has no soundboard; it uses a microphone pick-up and artificial amplification. Without amplification, electric guitars are very quiet.
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<h2 id="stethoscope">Stethoscope</h2>
<p><a href="/facts/Stethoscope/DrKjH4x1">Stethoscopes</a> roughly match the acoustical impedance of the human body, so they transmit sounds from a patient's chest to the doctor's ear much more effectively than the air does. Putting an ear to someone's chest would have a similar effect.
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<h2 id="building-acoustics">Building acoustics</h2>
<p>Acoustic transmission in building design refers to a number of processes by which sound can be transferred from one part of a building to another. Typically these are:
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<ol><li>Airborne transmission - a noise source in one room sends air pressure waves which induce vibration to one side of a wall or element of structure setting it moving such that the other face of the wall vibrates in an adjacent room. Structural isolation therefore becomes an important consideration in the <a href="/facts/Soundproofing/hKbTnCMq">acoustic design</a> of buildings. Highly sensitive areas of buildings, for example recording studios, may be almost entirely isolated from the rest of a structure by constructing the studios as effective boxes supported by springs. Air tightness also becomes an important control technique. A tightly sealed door might have reasonable sound reduction properties, but if it is left open only a few millimeters its effectiveness is reduced to practically nothing. The most important acoustic control method is adding mass into the structure, such as a heavy dividing wall, which will usually reduce airborne sound transmission better than a light one.</li>
<li>Impact transmission - a noise source in one room results from an impact of an object onto a separating surface, such as a floor and transmits the sound to an adjacent room. A typical example would be the sound of footsteps in a room being heard in a room below. Acoustic control measures usually include attempts to isolate the source of the impact, or cushioning it. For example, carpets will perform significantly better than hard floors.</li>
<li>Flanking transmission - a more complex form of noise transmission, where the resultant vibrations from a noise source are transmitted to other rooms of the building usually by elements of structure within the building. For example, in a steel framed building, once the frame itself is set into motion the effective transmission can be pronounced.</li></ol>

<ul><li>Carl Hopkins. Sound insulation. Elsevier. Imprint: Butterworth-Heinemann. 2007. <a href="/facts/ISBN_(identifier)/15AdSPa9">ISBN</a> 978-0-7506-6526-1.</li>
<li>Tomas Ficker. Handbook of building thermal technology, acoustics and daylighting. CERM. 2004 <a href="/facts/ISBN_(identifier)/15AdSPa9">ISBN</a> 80-214-2670-5</li></ul>
<h2 id="see-also">See also</h2>
<ul><li><a href="/facts/Absorption_(acoustics)/YNYesCgR">Acoustic absorption</a></li>
<li><a href="/facts/Acoustic_attenuation/FYX8rfsT">Acoustic attenuation</a></li>
<li><a href="/facts/Architectural_acoustics/13rruRvM">Architectural acoustics</a></li>
<li><a href="/facts/Attenuation_coefficient/ppCIsSGw">Attenuation coefficient</a></li>
<li><a href="/facts/Noise_pollution/dVwYwHMM">Noise pollution</a></li>
<li><a href="/facts/Soundproofing/hKbTnCMq">Soundproofing</a></li>
<li><a href="/facts/Sound_pressure/MgJAcp2I">Sound pressure</a></li>
<li><a href="/facts/Sound_reflection/BhcjDs79">Sound reflection</a></li>
<li><a href="/facts/Sound_transmission_class/Pk1W4kmG">Sound transmission class</a></li></ul>

Acoustic transmission open-in-new

Acoustic transmission