How to beep
    Back in the good old DOS days, we could just echo 
    the "bell" character (a binary 7) and we'd get a 
    beep. Not that simple any more. I know two ways 
    of making a beep. 

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    The first way misuses the DOS "choice" command. If 
    you type CHOICE at a DOS prompt (and hit Enter), 
    you will be expected to hit "y" or "n". If you 
    hit anything else, you get a beep. Try it now... 
    We can use the ECHO command to do our typing 
    for us:

echo aY | choice

    The above code gives a beep because "a" is not 
    accepted. Unfortunately, it also clutters the 
    screen. We can clean some things up by using the 
    "/n" option of choice:

echo aY | choice /n

    But we still see the final "Y" that gets entered. 
    Well, you COULD just follow the choice command 
    with a "clear screen" command:

echo aY | choice /n
cls

    And that works pretty darned good. Except when 
    you don't want the screen cleared... What we 
    need is a character to take the place of the "Y" 
    that is invisible. No, a space won't work. But 
    there IS an invisible character us old DOS hacks 
    know about that WILL work! It is a binary 255 
    character. You can make one in the DOS EDIT 
    program by holding the Alt key down while entering 
    255 ON THE NUMERIC KEYPAD. You won't see anything 
    in EDIT. If you open the file in Notepad, you see 
    a lower-case "y" with two dots above it. Now -- 
    back to CHOICE. You pick the characters CHOICE 
    responds to with the "/c" option. So we'll make 
    choice respond only to the binary 255 character. 
    I'll show the binary 255 character here as an 
    underscore "_", but you know what I really mean:

echo a_ | choice /c_ /n

    And that pretty much does it.
    FYI, the CHOICE command is not generally available under NT. 
    You can get it on the disk version of the Resource Kit, but
    not on the download version. If you really want to implement
    this Win9x solution on NT, you can always steal a copy of 
    CHOICE.EXE from a Win9x box. All reports I've heard say it
    works just fine. If a Win98 box isn't handy, download it:
    ftp://ftp.microsoft.com/Services/TechNet/samples/PS/Win98/Reskit/SCRPTING/


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    The other way I know is to change to QBASIC. This 
    has the advantage of working under NT. QBASIC still 
    beeps when you squirt out a binary 7 character. So 
    We just build a quick two-line BASIC program and 
    run it with QBASIC. You may want to replace 
    "beep.bas" below with an explicit path if you have 
    trouble (for example C:\WINDOWS\TEMP\BEEP.BAS):

@echo off
echo print chr$(7)> beep.bas
echo system>> beep.bas
qbasic /run beep.bas
del beep.bas
cls

    I know, I could just use QBASIC's built-in BEEP 
    command! So here it is too:

@echo off
echo beep> beep.bas
echo system>> beep.bas
qbasic /run beep.bas
del beep.bas
cls