1. First confirm the problem phenomenon, and judge whether it is a intermittent and probabilistic current sound problem. If it is possible, the reasons are as follows:
1) The network problem is related to the strength of the network signal at the time of the call. It is recommended to move to an area with better signal before making a call
2) Turn off the 4G network switch first and then make a call to confirm whether there is improvement. If there is improvement, it means that the current 4G network is a newly deployed network, and there is certain instability.
2. According to the phenomenon of the problem, if the sound of ""ZZZ"" appears when the volume is high, and it is judged that it has nothing to do with the network environment, the possible reasons are as follows:
1) If the voice of some people is fuller, the human ear is particularly sensitive to this part of the frequency, so when talking with some specific people, you may hear a slight noise, which will be more obvious for users with more sensitive ears .
2) When there is discomfort in the sense of hearing, please appropriately lower the volume by 1~2 bars, which can obviously solve this problem.
3) If you lower the volume and find that the volume is too low, please properly adjust the position of the earpiece and the human ear, and point the earpiece to the human ear.
4) For users who need to use mobile phone calls in high volume scenarios (such as noisy environments) for a long time, it is recommended that you use auxiliary devices such as earphones and Bluetooth earphones to make calls.