A hammer strike itself is a very short sound. It's usually sharp and percussive, lasting only a fraction of a second.
However, the *resonance* of the sound can be quite long depending on what the hammer is hitting. For example:
* Hitting a hard surface like metal or stone: The sound will be short and sharp, with a quick decay.
* Hitting a softer surface like wood: The sound might be longer and more resonant, with a slower decay.
So, the "shortness" of the hammer sound depends on the material it hits.