aidso Posted July 29, 2008 Share Posted July 29, 2008 Just found this site. As the max SPL is always asked and no-one ever seems to know thought this might help. http://soundadvice.info/thewholestory/glossary.htm Link to comment Share on other sites More sharing options...
Simon Lewis Posted July 29, 2008 Share Posted July 29, 2008 Just found this site. As the max SPL is always asked and no-one ever seems to know thought this might help. It's a good site...! Just a small point though.... the site mentions but doesn't emphasise the fact that what might be thought as being SPL figures are actually LEP,d, i.e. "a worker's daily exposure to noise at work (normalised to an 8 hour day), taking into account the average levels of noise the time spent in each area". Without this key distinction, many think that 85dB is an absolute barrier that must not be exceeded.... In fact, the only real maximum SPL are the peak sound levels. The average noise exposure is the 'level over a given time' exposure. Simon Link to comment Share on other sites More sharing options...
johndenim Posted July 29, 2008 Share Posted July 29, 2008 Hmmm, not sure I understand this quote correctly? "Three-decibel rule: The sound intensity doubles with every three dB increase. Thus sounds at 88 dB are actually twice as intense as they are at 85 dB and 115 dB is 1000 times as intense as 85 dB." John Denim. Link to comment Share on other sites More sharing options...
fatfrog Posted July 29, 2008 Share Posted July 29, 2008 Basically for every 3db added the percieved loudness doubles:) Alan Link to comment Share on other sites More sharing options...
Shez Posted July 29, 2008 Share Posted July 29, 2008 Basically for every 3db added the percieved loudness doubles:) No... It's about 10dB for the percieved loudness to double. Sound intensity is measured in watts per unit area and isn't the same thing as sound pressure. I'm sure Simon can explain this better than I can... Link to comment Share on other sites More sharing options...
Chappie Posted July 29, 2008 Share Posted July 29, 2008 According to Francis Rumsey: "In order to give the impression of a doubling in perceived loudness, an increase of some 9-10 dB is required. Although 6 dB represents a doubling of the actual sound pressure, the hearing mechanism appears to require a greater increase than this for the signal to appear twice as loud." Link to comment Share on other sites More sharing options...
Simon Lewis Posted July 29, 2008 Share Posted July 29, 2008 Sound pressure is just a measure of the pressure at a given point. sound intensity is (as Shez rightly points out) sound power per unit area. Sound power is the intrinsic acoustic power emitted by a source in all directions. Double the sound pressure, and the sound pressure level (i.e. 20log times [the pressure divided by a reference pressure]) will go up by 6dBDouble the sound intensity, and the sound intensity level (i.e. 10log times [the intensity divided by a reference intensity]) will go up by 3dBDouble the sound power, and the sound power level (i.e. 10log times [the power divided by a reference power]) will go up by 3dB Our perception of loudness does not exactly track the physical quantities outlined above, and over the years listening tests have indicated that for a sound to be perceived as twice as loud, its intensity must increase by a factor of 10. There's more on Hyperphysics if you want to explore Phons and Sones... Simon A concurrent post has been automatically merged from this point on. Three-decibel rule.... It's also worth pointing out that voltage is analogous to sound pressure, and electrical power analogous to sound power. A doubling of voltage = + 6dBA doubling of watts = +3dB Link to comment Share on other sites More sharing options...
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