The variable range of the frequency increases from 20 Hz to the high range, and the variable range decreases from the peak around 100 Hz to around 1000 Hz. The variable width of the frequency becomes large again in the high range from around 1000 Hz, and reaches the peak at around 10,000 Hz, and then becomes smaller again. The variable range around 100 Hz is about 15 dB, the range around 1000 Hz is about 5 dB, and the range around 10000 Hz is about 10 dB.