Sensitivity (Efficiency): The rating of a loudspeaker that indicates the level of a sound intensity that the speaker produces (in db) at a distance of one meter when it receives one watt of input power.The Efficiency or Sensitivity rating indicates how effectively a speaker converts electrical power from the amplifier into sound pressure. This is frequently related to larger magnet sizes, larger voice coil diameters, and more compliant suspensions. Optimized enclosures are essential in achieving maximum sensitivity, overall. The higher the Decibel number, the more efficient the speaker and the louder it will play with the same input power. While usually more expensive, an efficient speaker helps maximize the potential of the available power. Also - The relative sensitivity to the reception of RF signals in a tuner measured in dbf. The lower the number the better. Normal is now 10 to 14 dbf.