A volume above 80 decibels can be harmful to hearing. When the volume exceeds 120 decibels, direct damage can even occur. The chance of hearing damage depends on the listening frequency and duration.
#2 Can bluetooth devices of different brands be connected to each other?
Yes, bluetooth is a universal method that allows different devices equipped with bluetooth to connect to each other.
Dolby Atmos is a technology that ensures that the sound is reflected from the ceiling to where you are listening. This makes it possible to create a 5.1 effect with only 1 speaker.