The cardioid microphone picks up sound from a unidirectional point. The better you know your microphones, the higher quality of your final sound recording product, for microphones have the largest impact in the process of sound recording. And it is imperative that the sound recorder know the minute differences between micro phones, and how these variations potentially impact your recording. In addition to understanding the various types of microphones, it is also of fundamental importance to know where to position the microphone. Describe what you are doing on the recording.
Frequency response means how sensitive the microphone is to high and low tones.
Hold the microphone about three inches from your mouth. Talk into the front of the microphone and slowly rotate the microphone until you are speaking off axis, first to the left and then to the right. Try hissing like a snake into the microphone, which lets you hear the effect on the high end. Try this same exercise with an omnidirectional microphone. The loudness of your voice will not change with the angle, but the high frequency response will.