Ever wonder what's going on in the next room? Do you want to know what your kids are talking about on the phone in their rooms when they think you cannot hear? Listen through a wall with a glass. Drinking glasses are a good conduit for listening, as they funnel the sound waves coming through the wall to your ear. Just remember, you may hear things you do not want to know.
Get a drinking glass. An 236ml. drinking glass works well for listening through a wall. A wine glass is a good alternative if the room you are in is relatively noise-free.
Locate the area on the wall where the sound on the opposite side is most audible. The closer you are to the source on the other side, the more likely you are to hear exactly what is being said.
Place the rim of the glass on the wall. Position the glass gently so that you do not alert those talking to what you are doing.
Position your ear next to the bottom of the glass and listen, while holding it on the wall with your hand. Keep a firm grip on the glass so that it does not slide on the wall as you are listening.