on an android device like the LG, the sound is played back in stereo on headsets and headphones by default. if you now use a headset for two, for example, each with one headphone, the audio playback will be different. to prevent this, you can activate "mono audio" in the LG smartphone's helper controls. this combines the two audio channels into one, so the same sound is played on both earcups.

Android 9 | LG UX 9.0
Mono audio -  Open the  Settings
Mono audio -  Tap on  General
Mono audio -  Tap on  Accessibility
Mono audio -  Tap on  Hearing
Mono audio -  Tap on  Audio channel
Mono audio -  Choose between  Mono  and  Stereo
  1. Open the Settings
  2. Tap on General
  3. Tap on Accessibility
  4. Tap on Hearing
  5. Tap on Audio channel
  6. Choose between Mono and Stereo

LG Instructions