Sound, beep, delay, nosound etc missing in dos.h?

Let me tell u, that I AM A NEWBIE to C++..

I want to use sound in C++ (I use Borland Turbo C++ 4.5 because, this is used in our college..)

To use sound files, I browsed net and came to know that we may play sound using the
sound(), delay(), nosound(), in the dos.h directory.

But when i execute this program:
#include "dos.h"
int main()
{
sound(100); delay(5000); nosound(); return(0);
}

But it gives three errors:

Compiling NONAME00.CPP:
Error NONAME00.CPP 5: Call to undefined function 'sound' in function main()
Error NONAME00.CPP 5: Call to undefined function 'delay' in function main()
Error NONAME00.CPP 5: Call to undefined function 'nosound' in function main()

..
So I checked the dos.h directory fns (In HELP )and found there are none of the three fns in the list.. Not even the beep fn is available..

Please help me!!!!!!!!