The HY-929 listen through wall amplifier recorder is highly sensitive and capable of hearing / recording voice conversation through single brick wall, partition wall, wooden walls, doors, windows, floors, ceilings etc. It is capable of much more depending on surface material and building acoustics. For example some buildings you can hear through double brick insulated walls / 9" thick concrete. However one building is different to another and not possible all the time. It can also detect / hear leaking pipes, rodents, birds and other similar problems where this tool is very useful. Also included is useful 15cm/6" needle probe microphone for listening through keyhole, cracks, drilled hole etc. This product is sold as an investigation tool for law enforcement officers or licensed investigators.

Available with optional recording module to record everything heard and playback later. It records to microSD memory card and includes 8GB memory card.

This handheld device is simple to use and powerful, allowing you to listen and record conversations. Its working principle is very simple, you just need to switch on, plug in headphones, hold microphone to wall and adjust volume.

The HY-929 works by amplifying the vibration of sound waves. When people talk, sound waves hit wall causing vibrations, the Piezo wall contact microphone picks up these vibrations and amplifies them. The vibration picked up by microphone is amplified 20,000 times to create audible sound. The contact microphone sensor can sense tiny vibration that hits the wall, ceiling, floor etc and amplify it so that you can hear what is being said. If the sound is low, you adjust volume dial to increase magnification.