Shomer-Tec Laser Surveillance Defeater
All some people (i.e., my girlfriend) want is for people to listen to them. All other people want is for people to stop listening to them. For the first group I can try to extend my attention span to at least 7 minutes, even when they're giving a detailed story about some girl "stealing" some other girl's tangerine mermaid hair look and showing up with it first - 20 minutes early so she'd be sure to beat Amy there! - to the same party. For the second, the people who want to stop the listening, I can show you this: the Laser Surveillance Defeater from Shomer-Tec.
OK, the likelihood that you're being laser surveilled by your ex or your mama is pretty low. It's pretty damn expensive to direct an invisible laser beam through a window to pick up voices, and then demodulate, process, and amplify the sounds it collects with a receiver up to a mile away at the other end. Sales of that type of spy tool is also restricted in the US, mostly to government agencies. But.
If you're paranoid, or have legit reason to believe you're being tapped, the Laser Surveillance Defeater isn't that expensive at all and, when suction cupped to your window, interrupts, masks, and jams the laser at work (of course, I guess you'd need to buy one for every window, which jacks their cost right up). The Defeater transmits its own human voice frequencies to the window to drown out the real conversations. It has also been engineered to nullify "notch filters" laser surveillance devices use to isolate and enhance human voices.