Cornet and Speaking trumpet

Cornet noun - Something shaped like a hollow cone and used as a container.

Speaking trumpet and cornet are semantically related in trumpet topic. In some cases you can use "Speaking trumpet" instead a noun "Cornet", when it comes to topics like horn.

Speaking trumpet noun - A trumpet-shaped acoustic device to intensify and direct the human voice; formerly held to the ear by a hard-of-hearing person.

Cornet and speaking trumpet are semantically related in trumpet topic. You can use "Cornet" instead a noun phrase "Speaking trumpet", if it concerns topics such as horn.