From QB64.org wiki
The BEEP statement produces a beep sound through the sound card.
- BEEP can be placed anywhere to alert the user that there is something to do or an error has occurred.
- QB64 produces the actual "beep" sound through the PC's sound card, to emulate QBasic's beeping through the PC speaker.
- Older programs may attempt to produce a BEEP by printing CHR$(7) to the screen. This is no longer supported in QB64 after version 1.000.
- You may have to replace instances of PRINT CHR$(7) in older programs to the BEEP statement to maintain the legacy functionality.