I think it's a mistake putting the speaker in either the bottom or the top. The LG G6 comes with a single firing speaker at the bottom right side of the phone. This is a bad place to put a speaker because when you hold the G6 in landscape mode , like when watching movies or playing games, your hand will block it and lower the volume of its sound. The best place to put a speaker is actually on the right top side of the phone. So in landscape mode, the speaker will fire the volume on upside direction, where you hand is not holding the device.
I really can't understand the reason why LG has decided that this is the best place for it. It's a nightmare when you watch a movie or play a game you need to carefully position your hand so it won't block it. I had the same issue with many other Android phones and it really pissed me off. In this design, the designer assume that people are mostly holding the device in portrait orientation. Although this is true, putting the speaker on the right side doesn't block screw with the functionality of the phone. The LG G6 only has the microSD card slot on the right side at the top part, LG could put the speaker just underneath it.
Here, check this video out by pocketnow and you can see what I mean. The editor of this video shows how it's easy to unintentionally block the single-firing speaker. The same problem exists on the Samsung Galaxy S7 edge. If you have this phone, you probably know what I'm talking about. This is certainly a disadvantage for anyone who enjoy playing games and watch movies on his device. Not everyone will suffer from this issue, depends how big your hands are. You can also put your index fingers underneath the phone and not wrap it against the outer edge of the G6. Anyways, I wish it wasn't like that, just a bad design choice.