A speaker's sensitivity is a measure of the relationship between the power input and the sound output [source: B&H]. Here we will we explain more about sensitivity and how to measure it.

• Sensitivity is not about sound quality, but about how high the volume on your amplifier needs to be in order to make your speakers work their best. Therefore, sensitivity refers to a measure of how loudly the speaker will play given a certain electrical input level.
• Speaker sensitivity is measured in decibels per 1 watt per 1 meter, but is usually referred to as just decibels [source: JBL]. This is despite the fact that a decibel is really a mathematical unit used in the expression of different ratios concerning sound [source: University New South Wales].
• The sensitivities of different speakers can be compared because the audio industry has established standards for measuring speaker sensitivity, which is as follows. Place a microphone in front of the speaker, about 3.3 feet (1 meter) from the microphone. At this distance, most speakers at a given input of 2.83 volts will have an output of 80 to 90 decibels. Putting the microphone 6.6 feet (2 meters) instead of 3.3 feet (1 meter) from the speaker will make a big difference in the measured result. Every doubling of this distance results in a 6 decibel drop in the speaker output [source: Schneider].

So what does all this mean? Let's say you want to equalize two speakers in your band, so that they have the same decibel output. Both speakers produce their sound from 10 watts of power. The sound output of one speaker is 83 decibels, and the other speaker's output is 95 decibels. For every 3 decibel sensitivity difference between the two speakers, you will have to double the amplifier power of the lower speaker. In order to bring up the decibel level of the 83-decibel speaker to that of the higher speaker, you would have to increase the amplifier wattage to 160 watts -- 16 times as much [source: B&H]!