Objective: How can I amplify my phones speakers without electrical magnification?

Which of the following solutions is more sound in terms of naive physics reasoning?

OPT:
[+] Put your phone into a drinking glass or a bowl, face the phone toward yourself to boost the volume of its speakers.
[+] Put your phone into a drinking glass or a bowl full of water, face the phone toward yourself to boost the volume of its speakers.
Put your phone into a drinking glass or a bowl, face the phone toward yourself to boost the volume of its speakers.