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The scientific “unit” we call the decibel

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Re: The scientific “unit” we call the decibel

#101

Post by rusk »

taneq wrote: post #94
rusk wrote: post #84

Earlier quoted context omitted.

dB for sound in particular aligns with human experience. The (10 -) 1-10 on a volume knob typically aligns with a logarithmic scale because we hear differences in loudness at an order of magnitude. A linear volume knob would be frustratingly useless as you would have to crank it many many many times the higher up you want to go. Presumably hundreds of times. A traditional pot couldn’t do that of course but maybe you…

Ever have a cheap set of external speakers that got super loud in the first quarter turn of the volume knob but were pretty much the same loudness after that? Yeah, linear pot for the volume knob. No need for an encoder and software, though, logarithmic pots are readily available for precisely this reason. :)

No I’ve never had one of those LOL

Pots do log and lin scales but they only have a limited angular range.

Re: The scientific “unit” we call the decibel

#102

Post by [deleted] »

rusk wrote: post #84
svara wrote: post #62

Earlier quoted context omitted.

> makes me really doubt that the OP has any practical experience about the things they're talking about. Maybe not, but you can get used to many odd things given enough experience. I totally share the authors view. I don't usually have trouble grasping the definition of a unit, but dBs are just hilariously overloaded. The same symbol can literally mean one of two dimensionless numbers, or one of who knows how many ph…

dB for sound in particular aligns with human experience. The (10 -) 1-10 on a volume knob typically aligns with a logarithmic scale because we hear differences in loudness at an order of magnitude. A linear volume knob would be frustratingly useless as you would have to crank it many many many times the higher up you want to go. Presumably hundreds of times. A traditional pot couldn’t do that of course but maybe you…

[deleted]

Re: The scientific “unit” we call the decibel

#103

Post by hashhar »

coldtea wrote: post #50
timewizard wrote: post #13

Earlier quoted context omitted.

Human hearing perception response is logarithmic. This is part of the reason we use the unit. Our senses naturally work in that domain.

> Human hearing perception response is logarithmic. It is, but -50db to -47db (+3db) is not double perceived loudness. It's double power. About +6 or even +10db would be double perceived loudness.

Going from -50dB to -44dB is a much louder change than going from -6dB to 0dB.

Human hearing is logarithmic. The dB is measuring ratio of sound pressure level and it's accurate that +/-3dB is almost doubling/halving of the SPL.

Re: The scientific “unit” we call the decibel

#104

Post by [deleted] »

rusk wrote: post #96
IsTom wrote: post #93

Earlier quoted context omitted.

You could have log Watts or something, it doesn't have to be dB to be logarithmic.

That would be dishonest. You don’t adjust input power - you adjust attenuation EDIT if you did let’s say approximate power, or measure and present the consumed power (as some systems do) you would still be in a situation about how to present this data. Do you present your users with a simple 1-10 (logarithmic) or a 10 digit display which sweeps over vast ranges of uninteresting values. If you opted for a more compact…

[deleted]

Re: The scientific “unit” we call the decibel

#105

Post by mattmanser »

rusk wrote: post #101
taneq wrote: post #94

Earlier quoted context omitted.

Ever have a cheap set of external speakers that got super loud in the first quarter turn of the volume knob but were pretty much the same loudness after that? Yeah, linear pot for the volume knob. No need for an encoder and software, though, logarithmic pots are readily available for precisely this reason. :)

No I’ve never had one of those LOL Pots do log and lin scales but they only have a limited angular range.

I've actually noticed this two days ago with some bluetooth headphones and my phone.

The volume control on my android phone was acting just like this when my headphones were connected. When changing the volume with the phone only a small section of the bottom quarter of the volume control actually made a difference, but the volume controls on the headphone themselves were acting "normally".

Usually the phone volume is fine, it only screws up on bluetooth devices (my speakers + my headphones). I have to use the volume control on the device itself to have any good control.

This explains the weird behaviour, the phone volume changes are being sent linearly, but the headphone/speaker settings are correct and being set logarithmically.

i.e. somewhere a developer working on the bluetooth integration didn't understand the difference, screwed up and never tested it. That it's happening to both my Edifier speakers and my cheapo headphones probably means it's on the stock Android end (it's a pixel phone).

Re: The scientific “unit” we call the decibel

#106

Post by dns_snek »

neepi wrote: post #43
kristjank wrote: post #33

This seems exceedingly ignorant of the work decibels do in telecommunications, RF and fibre engineering. The voltage vs power relationship is something that exists and is a core memory of beginner blunders in the field, but it boils down to a simple 10 vs 20 division operation. Besides that, the decibel simplifies a lot of multiplying very small and very big numbers to summing of two-digit numbers that you can do in…

[flagged]

You haven't addressed any points the author has made, we don't need to have "experience" in a field to know that ambiguous units are ridiculous and bad.

When I'm buying a piece of string for my garden, I don't need to find an agricultural textbook to know whether "10 meters" in agriculture is the same as "10 meters" in engineering, and whether the definition of "meters" depends on whether the string is made out of cotton or polyester. The same is not true for "decibels". People seem to assume that we're too stupid to understand logarithms, we're not.

Re: The scientific “unit” we call the decibel

#108

Post by KeplerBoy »

IsTom wrote: post #93
rusk wrote: post #84

Earlier quoted context omitted.

dB for sound in particular aligns with human experience. The (10 -) 1-10 on a volume knob typically aligns with a logarithmic scale because we hear differences in loudness at an order of magnitude. A linear volume knob would be frustratingly useless as you would have to crank it many many many times the higher up you want to go. Presumably hundreds of times. A traditional pot couldn’t do that of course but maybe you…

You could have log Watts or something, it doesn't have to be dB to be logarithmic.

We have a unit for that. It's dBm and very easy to grasp. 0 dBm is 1 mW, every 10 dBm is an order of magnitude more (10 dBm = 10 mW).

dB is only confusing if people omit which quantities they are relating. If it's clear like in the case of dBm which relate to 1 mW, it's an awesome tool.

Re: The scientific “unit” we call the decibel

#109

Post by nabla9 »

Decibel is ridiculously overloaded concept.

It can be used to express and calculate relative change in power, amplitude ratios, and absolute change. All of these are different units and should always use different notation, but sometimes it's skipped.

Re: The scientific “unit” we call the decibel

#110

Post by Ekaros »

dns_snek wrote: post #106
neepi wrote: post #43

Earlier quoted context omitted.

[flagged]

You haven't addressed any points the author has made, we don't need to have "experience" in a field to know that ambiguous units are ridiculous and bad. When I'm buying a piece of string for my garden, I don't need to find an agricultural textbook to know whether "10 meters" in agriculture is the same as "10 meters" in engineering, and whether the definition of "meters" depends on whether the string is made out of co…

Well 10 millimetres of rain is different that 10 millimetres thickness for say branch...
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