fleabag Posted October 31, 2015 Share Posted October 31, 2015 I struggled to find the answer here on searches, there's just so much info. But, a guitarist ( yes one of those, not a bassist ) says that a human being with normal hearing, can detect an increase of less than 3db. I thought the minimum increase a human ear can detect was 3db, assuming the human has no impairment to the ears. Or maybe it's 2.9db or something. Is 3db just a ball park figure ? So, you have a bass cab that has a driver with rated efficiency of 100db. You set your amp volume at number 5. You get x amount of perceived volume. You then change the driver ( same cab , same TS spec, leave amp volume knob where it was ) but the driver is now 103db efficiency. Can one perceive a volume increase. ? All things being the same again, but with a driver with efficiency of 102.5db . Can that increase be perceived ? Or what about 102db... ? Quote Link to comment Share on other sites More sharing options...
Bill Fitzmaurice Posted October 31, 2015 Share Posted October 31, 2015 The decibel scale was originally calibrated by testing a few hundred people to determine the smallest average variation that they could hear in the midrange at normal conversation levels. That variation is 1dB. 3dB is what you get with a doubling of power, 6dB is what you get with a doubling of voltage swing, while 10dB (ten times the power) is perceived as a doubling of volume level. Quote Link to comment Share on other sites More sharing options...
fleabag Posted October 31, 2015 Author Share Posted October 31, 2015 So that guitarist was right ? Dammit 1db is just noticable but only in the midrange ? Quote Link to comment Share on other sites More sharing options...
Bill Fitzmaurice Posted October 31, 2015 Share Posted October 31, 2015 [quote name='fleabag' timestamp='1446302896' post='2898478'] So that guitarist was right ? [/quote]There's a first time for anything. [quote]1db is just noticable but only in the midrange ? [/quote]The midrange is what Bell Labs concentrated on, as their research was mainly related to telephone transmission, which in the 1920s was mainly in the midrange, for maximum intelligibility. They weren't so much concerned with audibility as they were transmission losses over long phone lines. Sensitivity varies with both frequency and with loudness, so 1dB as the threshold is by no means carved in stone. Quote Link to comment Share on other sites More sharing options...
fleabag Posted October 31, 2015 Author Share Posted October 31, 2015 (edited) Cheers Bill Oh man, i'll have to reply to the guitarist and say he was right. How depressing Edited October 31, 2015 by fleabag Quote Link to comment Share on other sites More sharing options...
Dan Dare Posted November 8, 2015 Share Posted November 8, 2015 That's interesting, Bill. I didn't realise it was based on researching peoples' actual experiences/opinions. Quote Link to comment Share on other sites More sharing options...
Skybone Posted November 10, 2015 Share Posted November 10, 2015 The decibel scale is based on a Logarithmic scale, not a linear scale. An increase of 3dB represents a noticeable doubling in the volume, so a 1dB gain may well be audible for most people, but most wouldn't really realise it (unless they have sensitive hearing). For example, a 50w guitar amp is rated at 100dB, where a 100w guitar amp is rated at 103dB. Although the Wattage rating is doubled, the dB rating is only 3dB, but the 100w amp will be twice as loud. Quote Link to comment Share on other sites More sharing options...
JJTee Posted November 10, 2015 Share Posted November 10, 2015 A +3dB increase of the same sound source will be perceived as a small increase in volume. A +/- 10 dB change in the same sound source will be perceived as a doubling or halving of volume. I don't think a 1dB change in level is audible outside lab conditions. Quote Link to comment Share on other sites More sharing options...
dannybuoy Posted November 10, 2015 Share Posted November 10, 2015 [quote name='Skybone' timestamp='1447160956' post='2905355'] The decibel scale is based on a Logarithmic scale, not a linear scale. An increase of 3dB represents a noticeable doubling in the volume, so a 1dB gain may well be audible for most people, but most wouldn't really realise it (unless they have sensitive hearing). For example, a 50w guitar amp is rated at 100dB, where a 100w guitar amp is rated at 103dB. Although the Wattage rating is doubled, the dB rating is only 3dB, but the 100w amp will be twice as loud. [/quote] The 100W amp will not be twice as loud, for that you'd be looking for 400W and hope your speakers don't melt before you reach that volume increase! Quote Link to comment Share on other sites More sharing options...
Bill Fitzmaurice Posted November 10, 2015 Share Posted November 10, 2015 [quote name='Skybone' timestamp='1447160956' post='2905355'] The decibel scale is based on a Logarithmic scale, not a linear scale. .[/quote]True, and that's why 10dB is perceived as a doubling of volume. 3dB is a doubling of radiated power, not perceived volume. Quote Link to comment Share on other sites More sharing options...
Skybone Posted November 10, 2015 Share Posted November 10, 2015 So all the Environmental Science I learned on my degree course, and all the associated text books I used, were obviously a load of old tosh. All the CITB Health & Safety qualifications, courses & literature I use for work, and HAVE to renew every three years, are obviously tosh as well. It's not just "stuff I saw on Wikiedia". Quote Link to comment Share on other sites More sharing options...
dincz Posted November 10, 2015 Share Posted November 10, 2015 [quote name='JJTee' timestamp='1447163484' post='2905401']I don't think a 1dB change in level is audible outside lab conditions. [/quote] It's easily noticeable outside a lab environment although you might not notice unless you're listening for it. Quote Link to comment Share on other sites More sharing options...
dincz Posted November 10, 2015 Share Posted November 10, 2015 [quote name='Skybone' timestamp='1447160956' post='2905355']For example, a 50w guitar amp is rated at 100dB, where a 100w guitar amp is rated at 103dB. Although the Wattage rating is doubled, the dB rating is only 3dB, but the 100w amp will be twice as [s]loud[/s] [i][b]powerful but only slightly louder[/b][/i]. [/quote] Fixed Quote Link to comment Share on other sites More sharing options...
dincz Posted November 10, 2015 Share Posted November 10, 2015 No luck with the mp3 attachment so maybe a Soundcloud link will work. This is what a 3dB change in level sounds like: https://soundcloud.com/dincz-1/3db Quote Link to comment Share on other sites More sharing options...
LukeFRC Posted November 10, 2015 Share Posted November 10, 2015 [quote name='Skybone' timestamp='1447171634' post='2905512'] So all the Environmental Science I learned on my degree course, and all the associated text books I used, were obviously a load of old tosh. All the CITB Health & Safety qualifications, courses & literature I use for work, and HAVE to renew every three years, are obviously tosh as well. It's not just "stuff I saw on Wikiedia". [/quote] Does Health and Safety qualifications cover [font="helvetica, arial, sans-serif"][color="#282828"]radiated power vs perceived volume? I've just a feeling Bill might end up using his physics and acoustical engineering knowledge more than once every 3 years....[/color][/font] Quote Link to comment Share on other sites More sharing options...
Skybone Posted November 11, 2015 Share Posted November 11, 2015 Not that I'm aware of, but they do cover exposure times & levels where hearing protection should be worn / MUST be worn for the work environment, skills and knowledge that Construction Site managers have to use every day. Quote Link to comment Share on other sites More sharing options...
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