Frequency Response
Definition
Frequency response is the range of audible frequencies a speaker or electronic component can reproduce. It is usually written as two frequencies and a tolerance, for example 45 Hz to 22 kHz (±3 dB). The lower number is bass extension. The upper number is treble extension.
A wider quoted range is not automatically better. The tolerance and how the measurement was taken matter. A speaker that is −10 dB at 40 Hz is not the same as one that is −3 dB at 40 Hz.
In a stereo system
Use bass extension to decide whether you need a subwoofer. Bookshelf speakers often roll off in the 40 to 70 Hz region. Towers and subs reach lower.
Room placement changes the bass you actually hear. A spec-sheet curve is measured in controlled conditions, not in your room. Pair frequency response with crossover settings when adding a sub.
Sensitivity is a different spec. It describes loudness for a given watt, not which frequencies the speaker covers.
