On page 462 in the chapter summary (aka «glossary») for chapter 17 there is an entry for decibel. It is simultaneously vague and not entirely correct.
The original, canonical, and best definition of decibel is as a measure of _gain_.
Furthermore, it is not some vague logarithmic measure; rather it is specifically one tenth of the common logarithm of the energy ratio (or equivalently the power ratio or intensity ratio). Hence:
gain = (10 dB) log₁₀(E2 / E1)
When properly used, the bel -- and hence the decibel -- are officially "accepted for use with the SI".
Similarly in the entry for intensity level, it should be spelled out the the log is the common logarithm.
On page 462 in the chapter summary (aka «glossary») for chapter 17 there is an entry for decibel. It is simultaneously vague and not entirely correct.
The original, canonical, and best definition of decibel is as a measure of _gain_.
Furthermore, it is not some vague logarithmic measure; rather it is specifically one tenth of the common logarithm of the energy ratio (or equivalently the power ratio or intensity ratio). Hence: gain = (10 dB) log₁₀(E2 / E1)
When properly used, the bel -- and hence the decibel -- are officially "accepted for use with the SI".
Similarly in the entry for intensity level, it should be spelled out the the log is the common logarithm.