Question 1

How many bels are in one decibel?

Accepted Answer

One decibel equals 0.1 B. decibels and bels are logarithmic level units of the same quantity, so they convert by a constant factor. The formula is B = log((1 × 1.122018^dB) ÷ 1) ÷ log(3.162278).

Question 2

How do I convert decibels to bels?

Accepted Answer

Multiply the value in decibels by 0.1. For example, 100 dB = 10 B.

Question 3

If it is a logarithmic scale, why is the decibels-to-bels factor constant?

Accepted Answer

Because decibels and bels both measure a level — the logarithm of the same dimensionless ratio. What is logarithmic is the dependence on that physical ratio (a fixed step in bels multiplies the ratio instead of adding to it), but between the level units themselves the factor stays constant: 1 dB = 0.1 B.

Question 4

What does doubling power or amplitude mean in decibels?

Accepted Answer

A decibel is a ratio scale, not an absolute value. Doubling power (a ×2 ratio) equals an increase of 3.0103 dB (10×log10(2)); doubling amplitude (e.g. voltage or sound pressure) equals an increase of 6.0206 dB (20×log10(2)). Formula: B = log((1 × 1.122018^dB) ÷ 1) ÷ log(3.162278).

Question 5

Where does the name "bel" come from?

Accepted Answer

The bel is named after Alexander Graham Bell and was the original unit for logarithmic signal loss at Bell Labs. In practice almost everyone uses its tenth part, the decibel (1 B = 10 dB), since it gives a more convenient numeric resolution.

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