You're asking for something that doesn't reproduce sound. Here are a few options that fit that description:

* A microphone: Microphones capture sound, but they don't play it back.

* A tuning fork: A tuning fork produces a specific sound when struck, but it doesn't play back recorded sounds.

* A light bulb: Light bulbs produce light, not sound.

Let me know if you want more examples, or if you have a specific context in mind.