The most common name for a piece of equipment that records sounds but not images is a microphone.

While other devices like audio recorders or dictaphones also record sound, they generally encompass both the microphone and the recording mechanism.

Here's a breakdown:

* Microphone: The core component that captures sound waves and converts them into electrical signals.

* Audio recorder/Dictaphone: A device that contains a microphone and a recording system to store the captured audio.

Therefore, a microphone is the most accurate and specific term for a piece of equipment that records sound only.