[DiogenesLamp]

They made flat ear horns long before this period. I saw a video from the early 1900s that purports to show a woman holding a cell phone to her head.

It was a flat ear horn. This may also be a flat ear horn.

[kosciusko51]

https://www.hearingaidmuseum.com/gallery/Non-Electric/EarTrumpets/Short%20Trumpets/info/germanovalpocket.htm

[RedMonqey]

Occam’s Razor.

Having eliminating all possibilities, the simplest answer is the correct one.

Ear horn.