bug#77715: [PATCH] Add ring-bell functions for mode line and header line.

[Drew Adams]

> There have been third-party packages that make this, however many of
> them diverge either in features or in faces.
> 
> I think Emacs should have had this built-in.

One alternative (it could be built-in):

https://www.emacswiki.org/emacs/download/echo-bell.el

It uses a defcustom instead of a defface, to define the background color for 
the string shown. The string is also a defcustom: "♪♪♪♪♪♪♪♪♪" by default. A 
third option is the number of seconds to show the string.