when voices sound too loud, you must use the physical side buttons . Adjusting the volume from the Home screen often only changes the ringer or media volume, not the in-call speaker. Immediate Solutions During a Call
To lower or adjust the call volume on your Go to product viewer dialog for this item.
: You can ask Siri to "Turn down the volume" during a call. Additional Settings to Check
: Press the Volume Down button on the left side of the device while the call is active to lower the earpiece or speaker volume.
: Swipe down from the top-right corner to open the Control Center and use the vertical volume slider.