If there’s one speaker spec worth looking at, it’s the sensitivity rating. Sensitivity tells you how much volume you’ll get out of a speaker at a given amount of power. It can affect not only your choice of speaker, but also your choice of stereo receiver/amplifier. Sensitivity is integral to Bluetooth speakers, soundbars, and subwoofers, even though those products may not list the specs.

The sensitivity of a speaker is pretty self-explanatory once you understand how it’s measured. Start by placing a measuring microphone or SPL (sound pressure level) meter exactly one meter away from the front of the speaker. Next, connect an amplifier to the speaker and play a signal; you want to adjust the level so that the amplifier is only delivering one watt of power to the speaker. Now watch the results, measured in decibels (dB), on the microphone or SPL meter. That’s the sensitivity of the speaker.

The higher a speaker’s sensitivity rating, the louder it will play at a given wattage. For example, some speakers have a sensitivity of around 81 dB. This means that they will only produce a moderate listening level with one watt of power. Want 84 dB? You’ll need two watts — that’s because every additional 3 dB of volume requires double the power. Want some nice, loud 102 dB peaks in your home theater system? You’ll need 128 watts.

Sensitivity measurements of 88 dB are about average. Anything below 84 dB is considered pretty poor sensitivity. Sensitivity of 92 dB or higher is very good and should be pursued.