{"id":3220,"date":"2008-10-01T22:29:29","date_gmt":"2008-10-02T04:29:29","guid":{"rendered":"http:\/\/www.conradaskland.com\/blog\/?p=3220"},"modified":"2008-10-15T09:38:44","modified_gmt":"2008-10-15T15:38:44","slug":"decibel-levels-and-perceived-volume-change","status":"publish","type":"post","link":"https:\/\/conradaskland.com\/blog\/decibel-levels-and-perceived-volume-change\/","title":{"rendered":"Decibel Levels and Perceived Volume Change"},"content":{"rendered":"<p>Here is information about decibel levels and perceived volume change. Here&#8217;s the quick read info, with supporting documentation below.<\/p>\n<ul>\n<li>3dB = twice the power<\/li>\n<li>6dB = twice the amplitude<\/li>\n<li>~10dB = twice the perceived volume<\/li>\n<li>Adding up two 12dB noise sources will get you, on average, 15dB (which will not sound twice as loud)<\/li>\n<\/ul>\n<p><!--more--><\/p>\n<p>I was working with a sound engineer and asked for a level to be dropped 3db. Their reply was &#8220;so you want it half as loud?&#8221; and I said &#8220;No, 3db&#8221; which was countered with &#8220;3db is half the volume&#8221;. So that&#8217;s what prompted me to look into decibel changes and how that translates to our real world perception.<\/p>\n<p>It is true that to increase a volume level by three db requires twice the power, which I think is where the confusion is. A doubling in power does not equal a doubling in audio perception.<\/p>\n<p>It was determined many years ago in controlled audibility testing, that the following rules were generally accurate among the population:<\/p>\n<ul>\n<li>6dB SPL increase is perceived as an approx. 50% increase in volume by a sample group.<\/li>\n<li>10dB SPL increase is perceived as an approx. 100% increase in volume by a sample group.<\/li>\n<\/ul>\n<p><strong>Another Explanation<\/strong><\/p>\n<p>A 3dB increase is twice as loud, in that increasing the level by +3dB by definition means twice as much audio energy is now being pumped into the room &#8211; well, actually 1.995 times as much, thanks to the wonders of logarithms. But the human ear&#8217;s response is also logarithmic, so twice the energy does not sound like twice the volume.<\/p>\n<p>There is, of course, no clear point where anybody&#8217;s going to say &#8220;ah, that&#8217;s now precisely double as loud as it was before&#8221;; there&#8217;s no little mental VU meter needle. But the general rule of thumb is that people tend to call a 10X, or 10dB, increase in audio power &#8220;twice as loud&#8221;, if you insist that they indicate such a point, and this is backed up by neurological studies.<\/p>\n<p>Every little 1dB step along the way, though, is noticeable (the general rule of thumb is that people can consciously notice a 1dB volume change, though a somewhat smaller increase in volume commonly causes people in both blind tests and hi-fi stores to think they&#8217;re now listening to a better system&#8230;), and having a whole lot of amplifier watts on call both makes sure that you&#8217;ve got headroom for sudden loud events and enough power to make the subwoofer shake the floor correctly.<\/p>\n<p><strong>For the super geeks, here&#8217;s the math:<\/strong><\/p>\n<p>For doublng of amplitude:<\/p>\n<p>6dB: 20 * log10(2\/1) = 20 * 0.3 = 6<\/p>\n<p>In application, this has always held true as long as the vector of both correlated(in phase) SPL sources were localized to within a small proportion relative to the wavelengths examined). Sound pressure change is only an amplitude change.<\/p>\n<p>Here is an easily illustrated electrical example of double amplitude = double power:<\/p>\n<p>V * I = W(power)<\/p>\n<p>Assume a 10 volt peak to peak AC signal @ 10 amperes\/current.<\/p>\n<p>10 * 10 = 100(power\/watts)<\/p>\n<p>Double voltage amplitude(voltage=20), same current\/amperes:<\/p>\n<p>20 * 10 = 200(power\/watts)<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Here is information about decibel levels and perceived volume change. Here&#8217;s the quick read info, with supporting documentation below. 3dB = twice the power 6dB = twice the amplitude ~10dB = twice the perceived volume Adding up two 12dB noise sources will get you, on average, 15dB (which will not sound twice as loud)<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"jetpack_post_was_ever_published":false,"footnotes":""},"categories":[32],"tags":[251,256,243,242,258,246,253,255,244,245,252,259,257,190,248,249,247,250,254],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"jetpack_shortlink":"https:\/\/wp.me\/p3C0LX-PW","_links":{"self":[{"href":"https:\/\/conradaskland.com\/blog\/wp-json\/wp\/v2\/posts\/3220"}],"collection":[{"href":"https:\/\/conradaskland.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/conradaskland.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/conradaskland.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/conradaskland.com\/blog\/wp-json\/wp\/v2\/comments?post=3220"}],"version-history":[{"count":2,"href":"https:\/\/conradaskland.com\/blog\/wp-json\/wp\/v2\/posts\/3220\/revisions"}],"predecessor-version":[{"id":3276,"href":"https:\/\/conradaskland.com\/blog\/wp-json\/wp\/v2\/posts\/3220\/revisions\/3276"}],"wp:attachment":[{"href":"https:\/\/conradaskland.com\/blog\/wp-json\/wp\/v2\/media?parent=3220"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/conradaskland.com\/blog\/wp-json\/wp\/v2\/categories?post=3220"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/conradaskland.com\/blog\/wp-json\/wp\/v2\/tags?post=3220"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}