A perfect speaker would recreate every frequency without attenuation or gain.  Unfortunately, there is no perfect speaker. The frequency response curve is a series of data points that represents how a speaker responds to a range of input frequencies. For speakers, the word “respond” represents the speaker's ability to recreate the input frequencies. When this data is plotted, it forms a frequency response graph that provides a visual representation of amplitude over frequency generated by the speaker. The vertical axis is labeled as the level of sound in decibels (dB) and the horizontal axis is labeled as the frequency in hertz (Hz).