DosBeep

#define INCL_DOSPROCESS

USHORT  rc = DosBeep(Frequency, Duration);

USHORT           Frequency;     /* Hertz (Hz) */
USHORT           Duration;      /* Length of sound */

USHORT           rc;            /* return code */

Example 

This example generates a beep for 1 second (1,000 milliseconds) at a 
frequency of 1,380. 

#define INCL_DOSPROCESS

#define BEEP_FREQUENCY 1380
#define BEEP_DURATION 1000

USHORT  rc;

   rc = DosBeep(BEEP_FREQUENCY,
                BEEP_DURATION);