This is a professional Guzheng tuner. It is designed to tune a 21-String Chinese traditional zither, i.e. Guzheng.
We have been focused on musical instrument turning for more than 10 years. We designed and manufactured a large number of popular professional digital tuners. As an upgrading, we recommend this App.
It is easy to use, pluck a string of Guzheng, as the sound enters the mobile phone, App can accurately identify the string and the deviation of frequency in cents.It works quite well, even in a noisy environment.
App only responds to musical tones in certain frequency range, while filtering out noise.