3db

[fleabag]

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... ?

[Bill Fitzmaurice]

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.

[fleabag]

So that guitarist was right ? Dammit

1db is just noticable but only in the midrange ?

[Bill Fitzmaurice]

[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.

[fleabag]

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

[Dan Dare]

That's interesting, Bill. I didn't realise it was based on researching peoples' actual experiences/opinions.

[Skybone]

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.

[JJTee]

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.

[dannybuoy]

[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!

[Bill Fitzmaurice]

[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.

[Skybone]

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".

[dincz]

[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.

[dincz]

[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

[dincz]

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

[LukeFRC]

[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]

[Skybone]

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.