[Reference pitch] The reference frequency can be set from 430Hz to 450Hz every 2Hz. [Tuner and Teacher ] You can choose the tuner function and the teacher function. The teacher will point out the sound of your performance is good, high or low. There are very tough teacher, relatively calm teacher, and less enthusiastic teacher. [Noise generation function] If the sound of your performance is high or low, you will be informed by noise. You can stop the noise.