Learn English – If I say First Monday or Second Monday of the Month what is the name for the First or Second Part

It's a battlement or crenellation. This consists of a parapet (a short wall on top of a roof) with cops or merlons (the solid parts) and crenels or embrasures (the parts you can look through or fire arrows through).

Those links are all to Wikipedia, which I know you might not consider a reliable source (although all of those articles contain references). So, here's the Oxford English Dictionary's definition of battlement:

An indented parapet at the top of a wall, at first used only in fortified buildings for purposes of defence against assailants, but afterwards in the architectural decoration of ecclesiastical and other edifices. The raised parts are called cops or merlons, the indentations embrasures or crenelles.

Also, you can read the entry for battlement in the 1911 edition of the Encyclopedia Britannica. You can also take a look at a page all about parts of castles in the Middle Ages for some related vocabulary.

The word you might be looking for is "earicon" (also sometimes known as an "earcon"), or the slightly less jargonic "audio icon".

You'd be hard-pressed to find this term documented in dictionaries or even online because it's mostly used as jargon within the advertising and audio/video production industries. Due to confidentiality agreements, I can't provide written materials to back this up, but I've worked in the audio branding business for eight years and every producer and designer I've met knows what an earicon is.

More formally speaking, there is a legal definition of a "service mark", which in the case of certain companies can consist of a unique sound and the spoken name of the company. This is used by many telephone service providers and other media-centric companies. Think of the "AT&T tone", which is followed by a female voice speaking the name of the company.

Finally, the broadest term that encompasses all representations of a company in media is "corporate identity."

---EDIT---

After talking with a few colleagues and checking various sources, here are some more candidates:

• auditory sign-off
• donut (a kind of ad that has music and pre-recorded audio at the beginning and end)
• jingle (originally referred to the musical logo of a company or brand)
• bed (the music over which the company name/brand is read)
• talk over (the spoken words played over the "bed")
• sonic branding
• sonic logo
• brand song