使用VB中的beep语句只能发出一种声音。如果想发出不同声音，可以使用API函数。

Option Explicit
Private Declare Function APIBeep Lib "kernel32" Alias "Beep" (ByVal dwFreq As Long, ByVal dwDuration As Long) As Long

Private Sub Command1_Click()
　 Dim frequency As Long

　 frequency = CLng(txtFrequency.Text)
　 APIBeep frequency, 500
End Sub