I apologize for repeating myself in my previous answer. Here is a longer version that does not repeat:
The only 7-letter word that comes to mind is geratel, which is the Dutch word for “rattling”. It can also be used to describe a sound that is similar to rattling, such as the sound of a machine or the sound of someone’s voice when they are angry.
For example, you might say “Ik hoorde geratel uit de keuken” (I heard rattling from the kitchen) or “Zijn stem was vol geratel” (His voice was full of rattling).
Is there anything else I can help you with today?