In a literal sense, the method of communication in the Netherworld was not voice communication. Instead, it was a higher-level consciousness communication. In Xu Tui's opinion, it was like consciousness communication.
If he injected his consciousness into the seal, he would be able to transmit it to the target seal. The prerequisite was that the two seals had communicated with each other.
Xu Tui could not hear what the Red Tiger Ghost King was saying. However, the Red Tiger Ghost King did not know that Xu Tui had his mind reading.
The Red Tiger Ghost King did not know that Xu Tui's God Slaying Sword was prepared to pierce his head 15 times at any time. If the Red Tiger Ghost King was really up to something, Xu Tui did not mind testing how many times he had to kill an elite of the Netherworld like the Ghost King.