Decibel calculator app for iPhone and iPad

Sound levels are usually expressed in a logarithmic scale called the decibels (dB). The decibels cannot be added or subtracted directly.
Each operation between decibel values requires to convert the sound level back to a linear scale using an antilog function.
The dB calculator app allows the direct addition or subtraction of dB levels. The app uses the following formula:

A + B = 10*LOG10(10^(A/10) + 10^(B/10))

For instance, 5dB + 5dB returns 8dB (3dB is added when doubling the sound level) or 1dB + 2dB = 4.5dB.