To cause a batch file to beep for attention, you need to send a BEL character.
The easies way to do this is to open a CMD prompt and CD to a folder in your path. Then type:
edit bell.bat
@echo<space><CTRL+P><CTRL+G><ENTER>
<ALT+S> (Saves bell.bat)
<ALT+X> (Exits edit)
NOTE: <> indicates that you type the key(s) within the
<>.
CONTROL CHARACTERS
Decimal Hexadecimal Character Mnemonic
00 00 NUL ^@
01 01 SOH ^A
02 02 STX ^B
03 03 ETX ^C
04 04 EOT ^D
05 05 ENQ ^E
06 06 ACK ^F
07 07 BEL ^G
08 08 BS ^H
09 09 HT ^I
10 0A LF ^J
11 0B VT ^K
12 0C FF ^L
13 0D CR ^M
14 0E SO ^N
15 0F SI ^O
16 10 DLE ^P
17 11 DC1 ^Q
18 12 DC2 ^R
19 13 DC3 ^S
20 14 DC4 ^T
21 15 NAK ^U
22 16 ETB ^W
23 17 SYN ^V
24 18 CAN ^X
25 19 EM ^Y
26 1A SUB ^Z
27 1B ESC ^[
28 1C FS ^\
29 1D GS ^]
30 1E RS ^^
31 1F US ^_