Vehicle horn horn. Bicycles often have a classic "bulb horn", operated by squeezing a rubber bulb attached to a metal horn. Squeezing the bulb forces air through a steel reed located in the throat of the horn, making it vibrate, producing a single note. The flaring horn matches the acoustic impedance of the reed to the open air, radiating the sound waves efficiently, making the sound louder. Other types of horns used on bicycles include battery-operated horns (sometimes even car horns on 12-volt circuits are incorporated) and small air horns powered by a small can of compressed gas. Oliver Lucas of Birmingham,
Black Man with a Horn track down what has happened to Mortimer, after Mortimer goes missing during a hurricane. A disturbing clue turns up in his bedroom. The story ends with his frightened next door neighbor having seen a black face at her window, something like a man wearing a gas mask or a snorkel. The narrator wonders how long it will be until the thing comes for him. Black Man with a Horn "Black Man with a Horn" is a horror novella by American writer T. E. D. Klein; part of the Cthulhu Mythos cycle, it originally published in "New Tales of the Cthulhu