A common dB scale used in audio recording is the dBm scale in
which the reference power is taken to be a milliwatt (1 mW)
dissipated by a 600 Ohm resistor. (See §F.3 for a primer on
resistors, voltage, current, and power.) The signal power is
typically averaged over some time period. In audio equipment,
exponentially weighted averaging is typically carried out using a
one-pole filter having a time-constant near 65.14 ms, which yields a
(time to reach 99% of the exponential target value) near 300
ms [11].