This is triggered by the server via a BEL control character. I will provide a switch option in the next 2.5.0 version to let you turn off this sound. And you can temporarily turn off this sound by following the steps below.

• Find the corresponding configuration file according to your session's Term, for example, if Term is xterm-256color, then the file is WindTerm_installed_path/terminal/terms/xterm-256color.term.
• Change the line:
  | (?<IgnoreControlCharacter> [\\x01-\\x04\\x06\\x10-\\x1a\\x1c-\\x1f]) # SOH, STX, ETX, EOT, ACK, DLE, DC1, DC2, DC3, DC4, NAK, SYN, ETB, CAN, EM, SUB, FS, GS, RS, US
  to:
  | (?<IgnoreControlCharacter> [\\x01-\\x04\\x06\\07\\x10-\\x1a\\x1c-\\x1f]) # SOH, STX, ETX, EOT, ACK, DLE, DC1, DC2, DC3, DC4, NAK, SYN, ETB, CAN, EM, SUB, FS, GS, RS, US

If you have any question, please tell me, thank you.

thx!!!!!