In a perfect world all devices would recreate every frequency at the exact same amplitude. In real life every device will have frequencies that it may amplify and frequencies that it will tend to reduce or attenuate. Frequency response curves show how a particular device responds to each frequency. SPL is plotted against frequency to indicate how the device will handle certain frequencies. As shown here, frequency is plotted on an exponential basis. Similar to dB’s, it allows the full range of human hearing to be fit in a compact space.