声学测量方面汇总

frogfish

<H1>Acoustic Measurements</H1>
<P>Acoustics deals with the science of sound, the transmission of vibrations in gasses and solids. Although acoustics implies that you can hear signals, acoustics also deals with signals both below (<a href="http://zone.ni.com/devzone/nidzgloss.nsf/webmain/78CDBFA997BFA460862569D700510B3E?OpenDocument" target="_blank" ><U>infrasound</U></A>) and above the highest frequencies of human hearing (<a href="http://zone.ni.com/devzone/nidzgloss.nsf/345429a29b12a2fc86256879000c059b/6410922bfd3d739c8625689a0062aa61?OpenDocument" target="_blank" ><U>ultrasound</U></A>). </P>
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<LI><a href="http://www.ni.com/devzone/encyclopedia/acoustics_measure.htm#measurements" target="_blank" >Measurements</A>
<LI><a href="http://www.ni.com/devzone/encyclopedia/acoustics_measure.htm#environments" target="_blank" >Environments</A>
<LI><a href="http://www.ni.com/devzone/encyclopedia/acoustics_measure.htm#signals" target="_blank" >Signals</A>
<LI><a href="http://www.ni.com/devzone/encyclopedia/acoustics_measure.htm#sensors" target="_blank" >Sensors</A>
<LI><a href="http://www.ni.com/devzone/encyclopedia/acoustics_measure.htm#measurementtips" target="_blank" >Measurement Tips</A>
<LI><a href="http://www.ni.com/devzone/encyclopedia/acoustics_measure.htm#units" target="_blank" >Units</A> </LI></UL>
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<TD class=subheader vAlign=top colSpan=2>Measurements</TD></TR>
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<P><a href="http://www.ni.com/devzone/encyclopedia/acoustics.htm" target="_blank" >Acoustic measurements</A> can deal with the purely scientific aspects of sound, such as <a href="http://zone.ni.com/devzone/nidzgloss.nsf/webmain/2CFA2455EB2C73C1862568C7004D1D18?OpenDocument" target="_blank" >acoustic pressure</A>, energy, or <a href="http://zone.ni.com/devzone/nidzgloss.nsf/345429a29b12a2fc86256879000c059b/3bb590a521a3d816862568c60060bd09?OpenDocument" target="_blank" >sound power</A>, but they can also be used to evaluate the annoyance (in the automotive industry, this is called Noise, Vibration, and Harshness, or <a href="http://zone.ni.com/devzone/nidzgloss.nsf/webmain/9DA217EA35AC7BC7C12568E700490307?OpenDocument" target="_blank" >NVH</A>), hearing damage potential, or the quality of acoustic transducers such as loudspeakers and microphones. Some general acoustic measurement types are as follows: </P>
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<LI><B>Building acoustic measurements</B> -- evaluate the sound insulation between rooms, as well as the noise transmission because of walking on floors.
<LI><B>Machinery noise measurements</B> -- measure the annoyance and/or potential hearing damage from office machines or vehicles such as<a href="http://www.ni.com/aerospace/" target="_blank" >aircraft</A>,<a href="http://www.ni.com/automotive/" target="_blank" >automobiles</A>, and other noise sources, such as power plants and factories.
<LI><B>Acoustic imaging measurements </B>-- used as a diagnostic tool for imaging applications such as imaging of the human body--where sound waves are ideal for measurement in soft tissue--as well as for fault and crack detection in mechanical devices (acoustic emission).
<LI><B>Sound quality measurements</B> -- used in the entertainment industry, from home stereo systems to surround sound theater sound systems, as well as in telephone headsets and mobile telephones. Audiometry is the measurement of the human ear's ability to hear, and is important in evaluating what type of hearing aids are desirable. </LI></UL>
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<TD><STRONG>Common Measurements:</STRONG><BR>intensity, <a href="http://zone.ni.com/devzone/nidzgloss.nsf/345429a29b12a2fc86256879000c059b/2c5a4ca44d09f4cb862568c6001aeb25?OpenDocument" target="_blank" >Pressure</A>, <a href="http://zone.ni.com/devzone/nidzgloss.nsf/345429a29b12a2fc86256879000c059b/28e76f025efa3d498625688000751f35?OpenDocument" target="_blank" >SPL</A>, <a href="http://zone.ni.com/devzone/nidzgloss.nsf/345429a29b12a2fc86256879000c059b/3bb590a521a3d816862568c60060bd09?OpenDocument" target="_blank" >sound power</A>, <a href="http://zone.ni.com/devzone/nidzgloss.nsf/345429a29b12a2fc86256879000c059b/f9eb1b771e0752d48625689a0062c109?OpenDocument" target="_blank" >particle velocity</A>, <a href="http://zone.ni.com/devzone/nidzgloss.nsf/345429a29b12a2fc86256879000c059b/28e76f025efa3d498625688000751f35?OpenDocument" target="_blank" >SPL</A> (<a href="http://zone.ni.com/devzone/nidzgloss.nsf/345429a29b12a2fc86256879000c059b/6b21c0ef2804470c8625689a0067af76?OpenDocument" target="_blank" >fast</A>, <a href="http://zone.ni.com/devzone/nidzgloss.nsf/10ce50b61f969f5a86256879000d3a01/7d50f98973d5c5058625689a0067c36b?OpenDocument" target="_blank" >slow</A>, <a href="http://zone.ni.com/devzone/nidzgloss.nsf/10ce50b61f969f5a86256879000d3a01/e8eb9dcc3cbe186c862568c8005c8c76?OpenDocument" target="_blank" >impulse</A>, <a href="http://zone.ni.com/devzone/nidzgloss.nsf/345429a29b12a2fc86256879000c059b/d33efa805a70616b862568c60059c8b1?OpenDocument" target="_blank" >Leq</A>, <a href="http://zone.ni.com/devzone/nidzgloss.nsf/345429a29b12a2fc86256879000c059b/9f2eb738a2e8a9ae862568a100819b40?OpenDocument" target="_blank" >SEL</A>, <a href="http://zone.ni.com/devzone/nidzgloss.nsf/345429a29b12a2fc86256879000c059b/0cda3b130b6580238625687b005a9d3f?OpenDocument" target="_blank" >dB(A)</A>, LN), <a href="http://zone.ni.com/devzone/nidzgloss.nsf/345429a29b12a2fc86256879000c059b/656b20ef2f4127558625689a0063e059?OpenDocument" target="_blank" >absorption</A>, <a href="http://zone.ni.com/devzone/nidzgloss.nsf/345429a29b12a2fc86256879000c059b/f9fb4e6121cdfbe28625686a0078b768?OpenDocument" target="_blank" >reflection</A>, <a href="http://zone.ni.com/devzone/nidzgloss.nsf/345429a29b12a2fc86256879000c059b/1a21ece58ce762498625686a0078b78e?OpenDocument" target="_blank" >tranmssion</A>, <a href="http://zone.ni.com/devzone/nidzgloss.nsf/345429a29b12a2fc86256879000c059b/4e3b664ab6e272548625686a0078b769?OpenDocument" target="_blank" >reverberation</A>, <a href="http://zone.ni.com/devzone/nidzgloss.nsf/345429a29b12a2fc86256879000c059b/f39c3cb5b60bb396862568c6001a8b8e?OpenDocument" target="_blank" >sound quality</A>, <a href="http://zone.ni.com/devzone/nidzgloss.nsf/345429a29b12a2fc86256879000c059b/1b03d132004f32038625686a0078b765?OpenDocument" target="_blank" >loudness</A>, <a href="http://zone.ni.com/devzone/nidzgloss.nsf/345429a29b12a2fc86256879000c059b/0174abcaf438c613862568c6005c852a?OpenDocument" target="_blank" >Sabine</A>, <a href="http://zone.ni.com/devzone/nidzgloss.nsf/browse?OpenForm&amp;arg1=class&amp;val1=Acoustics&amp;arg2=type&amp;val2=Measurement&amp;get=docs" target="_blank" >more...</A></TD></TR></TABLE></TD></TR></TABLE></P>
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<TD class=subheader vAlign=top colSpan=2>Environments</TD></TR>
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<P>The most common <a href="http://zone.ni.com/devzone/nidzgloss.nsf/webmain/62E64F4028A2D77C862568C6005E4B84?OpenDocument" target="_blank" >acoustic measurement environment</A> is a specialized <a href="http://zone.ni.com/devzone/nidzgloss.nsf/345429a29b12a2fc86256879000c059b/62e64f4028a2d77c862568c6005e4b84?OpenDocument" target="_blank" >test chamber</A> that serves two main purposes:
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<LI>Provides an environment where the relationship between sound power and sound pressure is well known
<LI>Reduces or eliminates interference from intruding noises, such as environmental noises from the operation of support equipment, mechanical equipment, automobiles, trucks, aircraft, and rail traffic. </LI></UL>
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<P>Depending on the type of acoustic measurement you are making, the most appropriate test chamber varies as follows:
<UL>
<LI><B>Sound power measurements</B> require different types of acoustical test chambers and environments depending on the degree of accuracy required:
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<LI>Precision Grade: Anechoic Chamber, Hemi-Anechoic Chamber, and Reverberation Chamber
<LI>Engineering Grade: Hemi-Anechoic Chamber and Free-Field Chamber
<LI>Survey Grade: Free-Field Chamber and Natural Environment </LI></UL>
<LI><B>Sound intensity measurements</B> require a Free-Field Chamber and Natural Environment.
<LI><B>Sound quality measurements</B> require a Free-Field Chamber and Natural Environment. </LI></UL>
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<TD><STRONG>Common Environments:</STRONG><BR><a href="http://zone.ni.com/devzone/nidzgloss.nsf/345429a29b12a2fc86256879000c059b/b6517bcda9953bc48625689a00658440?OpenDocument" target="_blank" >free field</A>, <a href="http://zone.ni.com/devzone/nidzgloss.nsf/345429a29b12a2fc86256879000c059b/da6b215a63c571608625689a00659693?OpenDocument" target="_blank" >diffuse</A>, <a href="http://zone.ni.com/devzone/nidzgloss.nsf/345429a29b12a2fc86256879000c059b/0f1a65eac53a6f78862568c6005ba183?OpenDocument" target="_blank" >reverberant</A>, <a href="http://zone.ni.com/devzone/nidzgloss.nsf/345429a29b12a2fc86256879000c059b/77c719f025155bd9862568c6005b5b6c?OpenDocument" target="_blank" >hemi-anechoic</A>, <a href="http://zone.ni.com/devzone/nidzgloss.nsf/345429a29b12a2fc86256879000c059b/f37b6f003ec03bef862568c6005d6e65?OpenDocument" target="_blank" >flanking</A>, <a href="http://zone.ni.com/devzone/nidzgloss.nsf/345429a29b12a2fc86256879000c059b/2411e5820cc3da1b862568c6005d7a97?OpenDocument" target="_blank" >structure-borne</A>, <a href="http://zone.ni.com/devzone/nidzgloss.nsf/345429a29b12a2fc86256879000c059b/6df323a7d78bfcc1862568c6005b7863?OpenDocument" target="_blank" >standing wave</A></TD></TR></TABLE></TD></TR></TABLE></P>
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<TD class=subheader vAlign=top colSpan=2>Signals</TD></TR>
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<TD>The following types of signals are commonly used to measure and describe acoustic characteristics: <a href="http://zone.ni.com/devzone/nidzgloss.nsf/10ce50b61f969f5a86256879000d3a01/4f2196a5af95f70a86256880006cedc2?OpenDocument" target="_blank" >white noise</A>, <a href="http://zone.ni.com/devzone/nidzgloss.nsf/345429a29b12a2fc86256879000c059b/b356ada3bfeabe0486256880006cfb54?OpenDocument" target="_blank" >pink noise</A>, <a href="http://zone.ni.com/devzone/nidzgloss.nsf/345429a29b12a2fc86256879000c059b/5b8f5820e3a3f0ed862568800070a7fd?OpenDocument" target="_blank" >1/3 octave noise</A>, <a href="http://zone.ni.com/devzone/nidzgloss.nsf/345429a29b12a2fc86256879000c059b/6410922bfd3d739c8625689a0062aa61?OpenDocument" target="_blank" >ultrasound</A>, <a href="http://zone.ni.com/devzone/nidzgloss.nsf/10ce50b61f969f5a86256879000d3a01/e9b04e8a7b2a3a9d8625686b00753285?OpenDocument" target="_blank" >noise</A>, <a href="http://zone.ni.com/devzone/nidzgloss.nsf/10ce50b61f969f5a86256879000d3a01/e9b04e8a7b2a3a9d8625686b00753285?OpenDocument" target="_blank" >pure tone</A>, <a href="http://zone.ni.com/devzone/nidzgloss.nsf/345429a29b12a2fc86256879000c059b/16333afe03bba60e862568c6005592e2?OpenDocument" target="_blank" >periodic</A>, <a href="http://zone.ni.com/devzone/nidzgloss.nsf/10ce50b61f969f5a86256879000d3a01/1a3bb0b8b55afc0f86256880006dcbb1?OpenDocument" target="_blank" >impulse</A>, <a href="http://zone.ni.com/devzone/nidzgloss.nsf/browse?OpenForm&amp;arg1=class&amp;val1=Acoustics&amp;arg2=type&amp;val2=Signal&amp;get=docs" target="_blank" >more...</A></TD></TR></TABLE></P>
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<TD class=subheader vAlign=top colSpan=2>Sensors</TD></TR>
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<TD>The following <a href="http://zone.ni.com/devzone/devzone.nsf/webproducts/D884C30CBEEFA8968625684A004EE20F?opendocument" target="_blank" >sensors</A> are commonly used to collect acoustic measurement data: <a href="http://zone.ni.com/devzone/nidzgloss.nsf/345429a29b12a2fc86256879000c059b/92e13d4268db99d68625689a00667772?OpenDocument" target="_blank" >condenser microphone</A>, <a href="http://zone.ni.com/devzone/nidzgloss.nsf/345429a29b12a2fc86256879000c059b/c5dbfc5251ee33328625689a0065dd6f?OpenDocument" target="_blank" >hydrophone</A>, <a href="http://zone.ni.com/devzone/nidzgloss.nsf/10ce50b61f969f5a86256879000d3a01/e40854c7c44116148625687100567ea0?OpenDocument" target="_blank" >accelerometer</A>, <a href="http://zone.ni.com/devzone/nidzgloss.nsf/345429a29b12a2fc86256879000c059b/fdb0d15d6fd35b378625689a006923ec?OpenDocument" target="_blank" >sound intensity probe</A>, <a href="http://zone.ni.com/devzone/nidzgloss.nsf/345429a29b12a2fc86256879000c059b/48852975b9cf276f8625689e005fb667?OpenDocument" target="_blank" >smart transducer</A>, <a href="http://zone.ni.com/devzone/nidzgloss.nsf/345429a29b12a2fc86256879000c059b/93f26491cda02e208625689a0069b073?OpenDocument" target="_blank" >pistonphone</A>, <a href="http://zone.ni.com/devzone/nidzgloss.nsf/browse?OpenForm&amp;arg1=class&amp;val1=Acoustics&amp;arg2=type&amp;val2=Sensor&amp;get=docs" target="_blank" >more...</A></TD></TR></TABLE></P>
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<TD class=subheader vAlign=top colSpan=2>Measurement Tips</TD></TR>
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<TD>Explore the following topics for tips on making acoustic measurements: <a href="http://zone.ni.com/devzone/nidzgloss.nsf/10ce50b61f969f5a86256879000d3a01/219150035185d5578625689a0065c9d6?OpenDocument" target="_blank" >microphone use</A>, <a href="http://zone.ni.com/devzone/nidzgloss.nsf/10ce50b61f969f5a86256879000d3a01/2b080ce5254ebb828625686a00793dbc?OpenDocument" target="_blank" >averaging</A>, <a href="http://zone.ni.com/devzone/nidzgloss.nsf/10ce50b61f969f5a86256879000d3a01/99ea2e337c36e83e8625686c0009008d?OpenDocument" target="_blank" >calibration</A>.</TD></TR></TABLE></P>
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<TD class=subheader vAlign=top colSpan=2>Units</TD></TR>
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<TD>The following units are commonly used in acoustic measurements: <a href="http://zone.ni.com/devzone/nidzgloss.nsf/10ce50b61f969f5a86256879000d3a01/b67efb2428c716c58625686a00793f0b?OpenDocument" target="_blank" >dB</A>, <a href="http://zone.ni.com/devzone/nidzgloss.nsf/10ce50b61f969f5a86256879000d3a01/7cb508b965ed13a08625689a006190d6?OpenDocument" target="_blank" >Pascal</A>, <a href="http://zone.ni.com/devzone/nidzgloss.nsf/345429a29b12a2fc86256879000c059b/0cda3b130b6580238625687b005a9d3f?OpenDocument" target="_blank" >dB(A)</A>, <a href="http://zone.ni.com/devzone/nidzgloss.nsf/345429a29b12a2fc86256879000c059b/9f2eb738a2e8a9ae862568a100819b40?OpenDocument" target="_blank" >SEL</A>.</TD></TR></TABLE></P>

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