Use speakers with good frequency response as much as possible.
　　When the phone is tilted, the distance difference between the left and right loudspeakers into the ear becomes longer.
　　Try not to use resonance devices around the loudspeaker assembly.
　　Separate the left and right speakers as much as possible.
　　Reduce the characteristic difference of left and right loudspeakers as much as possible.
　　Listen in the center of the left and right speakers as much as possible.
　　When reproducing the stereo sound field, the communication between the speaker and the ear is most appropriate at the center of the left and right speakers, that is, the head position. When the mobile phone is tilted, the distance difference between the left and right loudspeakers and ears increases, and the distance of sound transmission changes, which will affect the sound effect. Especially when the loudspeaker is placed on both sides, it is easier to increase the distance difference than on the front.