a-weighting acoustics alexander graham bell amplifier amplitude apparent magnitude arithmetic attenuator audiogram bell labs bell system bode plot byte cable television carrier frequency dbfs db drag racing dbc dbm dbrn dbrnc dimension dipole antenna electric current electrical impedance electronic circuit electronic component electronics engineering equal-loudness contour faq free space full scale gain harmonic heat hertz international committee for weights and measures joule link budget logarithm long and short scales mile million minimum audibility curve neper optical density optical fiber optical link optics overload radar cross section reference noise resistor response richter magnitude scale root mean square scientific notation signal noise sound sound intensity level sound power level sound pressure telecommunication telephone underwater acoustics volt voltage voltage source watt weighting filter