3. Log vs decibel scale - Loudness and Level
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- Опубликовано: 23 июл 2024
- In this video, we'll look at different ways we can represent the pressure values on a one dimensional scale. We'll quickly find out that plotting a vast range of values on a linear scale can lead to loss of resolution at the lower range of values, and we'll see how a logarithmic scale is better suited to represent exponential data. We'll learn the basics of logarithms or log, as a substitute for the exponent or power function. We delve further by representing pressures not on their own, but as ratios, with the baseline pressure value as the threshold of human hearing. We'll explore a unit that is most commonly associated with measurement and representation of pressure, the bel and decibel. We'll derive the equation of converting pressure into dBSPL, and answer a couple of commonly asked questions in the process.
Find the full playlist here: • Loudness and Level
Content:
00:00 Pressure and the linear scale
02:45 Mathematics of logarithms
04:15 Pressure ratios
05:41 Bel and decibel
10:56 Common questions
In this module on Loudness and Level we'll delve into how our sense of loudness is different for different frequencies and all the nuances associated with hearing. We'll look at level, and the technical ways of measuring and calculating the amplitude of signals. And finally we’ll look at a new way of measuring loudness that’s all the rage at the moment, the Loudness unit. It has redefined the standard used in streaming and broadcast, and promises to bring an end to the age of super compressed audio and the so-called loudness war.
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Dude!, you just made me understand what an entire semester in university couldn’t, thanks a lot man!
Glad to help mate! :)
You may not realize how helpful are these videos, but they truly are. Thank you.
Thanks for that! I really appreciate the motivation :)
Super helpful! And you corrected a lot of poor teaching id received in the past. Love the build up from fundamentals.
Thank you. No one can explain this even better!
wow what a great video and explanation
, you should get an award for that
Haha! Thanks..
after seeing such videos only we release that, RUclips could be so much useful.
By far the best explanation about decibel scale! Awesome job!!
Thanks so much!
No one explained it better. Glad I bumped into your channel.
I'm glad you did!
Wonderfully explained, finally I got a more accurate understanding about it. Akash, you're the best!
Very glad that it helped! Thanks for checking it out!
Akash, extremely good pedagogics! Extremely good verbal and visual presentation.
Thanks so much! I'm glad you enjoyed the way it's presented. I try to make it as intuitive as possible. It might not always be evident if something is intuitive or not, as people have differing depths to their knowledge
Thank you for making these videos! Very informative, very well done.
You're welcome mate!
BRUH!! Amazing Videos!!!! Thanks so much very well organized information!!
Total gratitude for your clear explanations. Very appreciated!
You're welcome mate! Thanks for checking it out..
Absolutely Crazy Explanation! Thanks for this!
Glad it was helpful!
Very well explained Akash, cheers!
superb series of video; best explenation i ever got.
thx for the good work
Great explanation!
Great video. Thanks!
A really great job at explaining this topic, thank you
You're welcome! Thanks for checking it out
Nice video! Thank you!
Excellent! Thank you man!
great video, very direct explanation, keep up the great work
Cheers!
Good Stuff!
I loved this video !! This is totally amazing !!
Cheers!
Excellent again.
great explanation
Very fine work
This is by far the best explanation of the concept that I have ever seen. And I have a degree in Physics. ;-)
Haha..thank you! I'm glad you approve!
I have a question: Why is 0 decibels the maximum level for mixing a song in a digital audio workstation? Is this so we wont hear what pressure the computer is physically exerting..so we can focus on routing the project to an amplifier of our own like headphones to actually hear it this way?
So, let's split the question up. The computer doesn't know anything about pressure. Pressure is a quantity that only exists in the physical world. In analog devices, like microphones, the pressure of the physical medium is converted into changes in voltage. In a computer, these changes in voltage are represented as binary data. All the computer knows is what the maximum value of this data can be, and minimum value it can take.
For example, if you have a 16 bit recording (signed PCM -32768 and +32767), each audio sample can theoretically have a maximum level of 32768, and a minimum level of 0. So in a computer, since each sample is represented by a fixed size, you cannot have any levels above or below this.
Now, going back to your first question, why is it 0dBFS in DAWs. That's a choice that computer engineers have made. They have chosen the reference level to be the maximum possible value that an audio sample can hold. So dBFS calculations for 16 bit audio are made like this: 20log(value/32768)
So if you apply this formula for the highest sample value (32768), you get 20log(1) = 0dBFS
Any values above this are clipped. The lowest value would be -96dBFS, below that, it's just silence.
There is no relation between dBSPL (pressure) and dBFS (full scale amplitude in computers). Though they may have the same term "decibels" associated with it, they don't share any relationship.
What a content, amazing!
Thank you!
good, waiting for more digital audio explanation videos
amazing 🔥
This is a fantastic video and animation
Thanks mate! :)
just discovered your channel. very helpful
Glad you stumbled upon it!
thank you
Thankyou
Thanks!
Thanks for the support!
Great !
The best material I have ever seen!
One question though,
60dBspl + 60dBspl = 66dBspl according to your explanation.
Why sound pressure has power of 2? (=20log(P1/P0) not 10log(P1/P0))
Is it something to do with RMS?
Thanks very much!
Yea, the 10 or 20 multiplier is covered in the next video in the series, that should give you a good understanding as to why a certain multiplier is used. It's got to do with whether the quantity is a power quantity or a field quantity.
chapeau👍🏻
very good video. Isn't it the case that for every 3dBspl increase, the time you can be exposed to it without hearing damage is halved? Because of this, I thought +3dBspl was a doubling in sound pressure. I guess I was mistaken
Hey! Thanks for checking it out. Your statement about doubling sound pressure is a common cause for confusion.
We can calculate it right now!
We just need to find out what happens when pressure p is doubled. We can calculate dbSPL as:
dbSPL = 20 log (2p/p) = 20 log(2) = 20 * 0.301 = 6.02
So doubling pressure gets you +6dbSPL.
The +3db increase that you might've heard about elsewhere applies to power quantities, like Sound Intensity. Sound Intensity(SIL) can be calculated as:
dbSIL = 10 log (2I/2) = 3.01
So doubling intensity gets you +3dbSIL.
Does that make sense?
@@akashmurthy Ah I understand. If you want to double the sound pressure, you have increase dBspl with +6dB and if you want to double the sound intensity, you have to increase dBsil with +3dB. And the reason for this is that sound intensity includes the direction of sound, making the distance an exponential factor where sound pressure and distance is a linear relationship. Do I understand it correctly?
Regarding perception, "sound intensity" sort of implies that this is how we perceive loudness. Would a doubling in dBsil be perceived as a doubling in loudness?
Again man, thanks so much for these video's. Just checked 2 more and they are absolutely brilliant.
@@martijnbos9873 Well the reason for the difference is because of the physical relationship between pressure and intensity.
In physics, Intensity is proportional to the square of the pressure. That's the defining factor, not distance.
Squaring on the linear scale is multiplicative on the logarithmic scale (decibel scale). Don't worry about this statement if you don't get it.
And we perceive sound as pressure, not intensity. I mention this on the 5th video in the series!
Doubling pressure is equivalent to increasing by +6dbspl, does that mean loudness is doubled as well? Maybe, maybe not. Loudness is very subjective and is also dependent on frequency of the source material. You can say that increasing pressure anywhere between 6 to 10 dbspl could result in a perceived doubling of loudness.
@@akashmurthy Thanks for the explanation!
Hey OP it is excellent how video is presented. How do you make this kind of video
Cheers mate! I use After Effects
@@akashmurthy I hope you don't lose your passion. This channel is severely underrated!
How do you explain with animated illustrations? very comprehensive they are
Cheers mate..!
Please let me know , about animation tools?
Oh is that what you wanted to know? I record the audio for the explanation first. And then I animate the sequences using Adobe After Effects. That's pretty much it.
@@akashmurthy ohh , got the answer I wanted 👍👍thank you ji
absolutely great content. For the graphs at this point ruclips.net/video/3vqxAkmbqbA/видео.html, they look like they're interchanged. No?
"Yooler".