How to beep using PC speaker?

From Windows 7 onwards, you can no longer easily make sound via the internal speaker.

For Windows 7, we resolved the issue completely – we moved all the functionality that used to be contained in Beep.Sys into the user mode system sounds agent – now when you call the Beep() API instead of manipulating the 8254 chip the call is re-routed into a user mode agent which actually plays the sounds.

[…]

There were also some unexpected consequences. The biggest was that people started noticing when applications called Beep(). They had placed their PCs far enough away (or there was enough ambient noise) that they had never noticed when their PC was beeping at them until the sounds started coming out their speakers.

See here for details:

https://docs.microsoft.com/en-us/archive/blogs/larryosterman/whats-up-with-the-beep-driver-in-windows-7

Do you have any 32 bit Windows machines lying around? Try Console.Beep(); on one of those, the PC speaker will beep.

On 64 bit Windows (XP, Vista, 7 or 8) the driver to do this isn't present so it will come out of the speaker plugged into the machine instead.

Also, correct me if I'm wrong but I would hazard a guess that the beep you hear whenever your PC turns on is from your BIOS, before you actually hit Windows 8.

You can use SystemSounds.Beep for example: SystemSounds.Beep.Play();

See also: SystemSounds.Beep Property