The Scarlet King is a fictional character associated with the SCP Foundation, which is a collaborative writing project where authors create and share stories about anomalous objects, creatures, and phenomena. The Scarlet King's voice is not explicitly described in the SCP Foundation's canon or official documentation.
As a result, there is no definitive answer to what The Scarlet King's voice sounds like. Since it is a fictional character, any description of its voice would be purely speculative and based on personal interpretation or creative portrayals found in fan-made content.
If you are interested in specific interpretations of The Scarlet King's voice, I would suggest exploring fan art, audio adaptations, or discussions within the SCP Foundation community, where individuals may have shared their own ideas and representations of the character's voice.