![]() ![]() That is, relative to what the level was, it is now 6dB higher. Otherwise, just skip the calculator and read the examples below to help understand how decibels are used.Įxample One : you increase the volume on a mixer or amplifier by 6dB: this is actually doubling the voltage that will appear at the output (because 6dB is a factor of 2 – see table). The easy ones to remember are x10 = 20dB, x100 = 40dB and x1000 = 60dBįor those who want to see other ratios and decibel values, you can use this simple calculator.Double the voltage (x2) changes the output by 6dB (see examples below).There are some interesting points highlighted by this table: ![]() (I’m not showing the formulas or calculations because I reckon most people skip over them anyhow, and if you like formulas any search engine will give you as many as you like) But without getting into formulas etc, we need to accept the following summary of linear ratios of voltages and decibels. (Note: power measurements (like the power differences in an amplifier) use a similar but different formula). When we are talking about audio levels, we are looking at voltages, or sound wave amplitudes. A small change in decibels relates to a different change in the ratio of the two levels being compared. Also, a doubling in the side length does not double the area – it is a lot more than the double! This is an example of a non-linear relationship – in this case, a small increase in the side relates to a different increase in the area. In this example, you can see that increasing the side measurement does not have an equivalent increase in area, but a larger increase. Another example of a non-linear relationship is between the side of a square and the area of a square. This is because our range of hearing is so vast, that to use a linear scale we would be using figures from 0 – 1,000,000!Ī secret to understanding decibels is to note that decibels are non linear. So why use a decibel? You might have noticed that the volume control on most HiFi amps is marked in decibels, as is the markings on mixer level controls. For example, the line out of mixer might be at -10dB, this usually means it is 10dB below 0dB. Unfortunately, what it is relative to is often not mentioned when stating a decibel reading. There is no absolute level called a decibel. A decibel expresses a ratio. A decibel uses a logarithmic scale, not a linear scale like volts or watts – see below. A Bel is a very large unit, so the prefix deci (one tenth) is used. What is a decibel?Ī decibel is a tenth of a Bel, a unit of level, named after Alexander Graham Bell. But first, some basic questions and answers about decibels. These articles give a practical understanding on using decibels in audio work. If we have a speaker playing at 100W and we increase it by 1W, it’s also 1W “louder” but proportionally it’s a small unnoticeable change of 0.043dB.Decibels are widely used in audio, and often misunderstood. A small but noticeable change on perceived loudness. If you change the digital level (or the electrical level) by -10dB (more negative) the dB SPL level also drops by 10dB.ĭecibels are logarithmic (or “proportional”) like our hearing - If you have a speaker playing at 1 Watt and you double it to 2 Watts, that makes a 3dB increase. Normally, none of these levels are calibrated but they are directly correlated. There are also electrical dB levels (such as dBV). It will “show red” for potential clipping if it goes over 0dB.įor acoustic loudness (sound in the air) the 0dB SPL (Sound Pressure Level) reference is approximately the quietest sound that can be heard so dB SPL levels are positive. Internally, Audacity uses 32-bit floating point so Audacity itself won’t clip. With floating point audio, 0dB is a numerical value of 1.0 and for audio purposes there is essentially no upper or lower limit. A digital file may not have an exact-zero number, depending on where it’s sampled… The zero-crossing is usually in-between a positive and negative sample and the actual zero-crossing only occurs with the reconstructed analog output.Ģ4-bit audio files have bigger numbers and 8-bit files have smaller numbers but when you play the files everything is scaled automatically to match the bit-depth of the DAC and a 24-bit file is not “louder”. And there is a zero-crossing twice per cycle. Silence (-infinity dB) is a series of samples with a numerical value of zero. You can’t count any higher without more bits. If you have a digital file with those negative and positive peaks, it has 0dB peaks. With digital audio 0dBFS (0dB Full Scale) is the maximum you can “count to” with a given number of bits and digital dB levels are usually negativeġ6-bit signed integers can hold values between -32,768 and +32,767. Also, decibels are relative so you need a reference. ![]()
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