What In The World Is A Decibel?


One of the first terms you hear the most when you start recording music is "dee bee". Everyone launches the term, but how many musicians really know what it means?

The & # 39; bee & # 39; is written like this – dB – and is the abbreviation for & # 39; decibel & # 39; Uhoh! We now have access to the technique. Yes, it is a scientific term that represents a concept that is difficult to explain, especially without using equations or mathematical symbols. Do not worry though, because I will keep things simple.

When I taught recording engineering to high school students, I wanted to be able to explain the decibel in a fun and memorable way, so that they really understand what it represents. That day in class became known as Mr. Likes & # 39; famous "Decibel Reading".

In the recording industry, dBs are most often used when it comes to sound levels and signal levels, or volts. Before I get there, I'll talk about money. Anyone can relate to money, right?

Here you are. In the interest of this explanation, we will assume that the smallest increase in money is 1 dollar. When I was growing up, a very rich person was defined by $ 1 million and we called him "a millionaire". I know you consider yourself rich enough if you had a million dollars. Just like me. But over the years, a very wealthy person has become a "billionaire" – a person worth a billion dollars. What is the difference between a millionaire and a billionaire? This means that the billionaire has a thousand times more money!

We are learning today that the US government is in debt of $ 14 trillion! What is the size of a trillion dollars compared to a billion? Once again, it's a thousand times bigger!

If I wanted to draw a line on a piece of paper ranging from the smallest increase – 1 dollar – to 1 trillion dollars, and that I was using a one-tenth of an inch space for every dollar, my line should be 100 billion inches long! Believe me, it's too long for a piece of paper 11 inches long.

Could I have a way to demonstrate the difference between $ 1 and $ 1 trillion and have it fit on one piece of paper? Ahha! It is here that the decibel enters the image. Until now, we have compared amounts in dollars. When we compare quantities, we can also call a ratio. Comparing 1 billion to 1 million, one could write the number 1,000,000,000 divided by (or "above") the number 1,000,000. Notice that there are 9 zeros out of 1 billion and 6 zeros on 1 million. If we actually divide one billion into a million, we will have 1,000. How many zeros out of 1,000? You are right. There is 3. Hmmm. All we needed to do was subtract the number of zeros out of a million from the number of zeros out of a billion to get 3.

Scientists have used this knowledge to define a thing called logarithm. Do you remember that since your high school math? Well, it does not matter. In this case, all it means is how many times do we need to multiply by 10 to get another number? In our case, it is the number of zeros in the number. (Thank you for not bothering your brain trying to understand it for a number like 5!) For the moment, all we are interested in are nice round numbers, multiples of 10.

You can solve this problem yourself, but if we multiply by 10 the number of times 9, we will receive 1 billion. This means that the logarithm of 1 billion is 9. The logarithm of 1 million? Right. That's 6. What is the difference between 1 billion and 1 million in terms of logarithms? Right again. He is 3.

These numbers are called logarithms of base 10. Obviously, because you have to multiply by 10 the number multiplied by 10 to get the number. As you know, we use the decimal numbering system. It's called so because it's based on 10. You know, it's the number of fingers and toes you have. Scientists have proposed the decibel name for these ratios. The word has & # 39; deci & # 39; which refers to the number 10, and it has & # 39; beautiful & # 39; pay tribute to Alexander Graham Bell. So, the decibel.

D & # 39; agreement. What is the link with sound level and voltage? Now, you must know that we are comparing quantities of the same thing or establishing ratios for the same things. In our case, we use dollars. In the case of sound, these are the sound levels. Same thing for the tension.

Another definition. The decibel is defined in the following way: the number of decibels is equal to 10 times the logarithm (of the base 10) of the ratio of the 2 quantities of things that we compare. Therefore, we can now say that $ 1 trillion is 120dB against 1 dollar. That's because the log (abbreviation of logarithm) of 10 is equal to 1 and that of $ 1 trillion to 12. The ratio would be 12 to 1, or 12. Then we multiply it by 10 and get 120 dB.

Phew! Have you followed that? Whatever it is, remember our initial challenge? How to show the difference between $ 1 and $ 1 trillion on a single sheet of paper? If we now let 1 tenth of an inch represent 1 dB, it only takes 12 inches! D & # 39; agreement. D & # 39; agreement. This will not hold on an 11 inch piece of paper. But it's a lot less than 100 billion inches.

You probably understand the fact that 0 dB and 120 dB are terms that you hear all the time in the recording industry when you talk about sound levels. You now know why the decibel is used to refer to sound levels. It's much easier to talk about numbers like 0dB, 20dB, and 120dB than talking about 1 micro something and 20 micro somethings, or 10,000 micro somethings.

You see, the sound levels processed by the human ear are going to a microPascal (no way I define it in this article!) To a trillion microPascals. You guessed it. It is 120 dB. Just like the dollars.

You now know what a decibel is and why it is used when comparing large differences in quantities or quantities of items. It could be apples. The difference between one billion apples and one apple would be 90 dB. Go out now and breathe fresh air.

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