Diaphone

The diaphone is a noisemaking device best known for its use as a foghorn: It can produce deep, powerful tones, able to carry a long distance. Although they have fallen out of favor, diaphones were also used at some fire stations and in other situations where a loud, audible signal was required.

History

The diaphone horn was based directly on the organ stop of the same name invented by Robert Hope-Jones, creator of the Wurlitzer organ. Hope-Jones' design was based on a piston that was closed only at its bottom end and had slots, perpendicular to its axis, cut through its sides; the slotted piston moved within a similarly slotted cylinder. Outside of the cylinder was a reservoir of high-pressure air. Initially, high-pressure air would be admitted behind the piston, pushing it forward. When the slots of the piston aligned with those of the cylinder, air passed into the piston, making a sound and pushing the piston back to its starting position, whence the cycle would repeat. A modification of Hope-Jones' design was patented by John Pell Northey, head of the Northey Co. Ltd. of Toronto, Ontario, Canada, which manufactured pumps and small gasoline engines. Northey added a secondary compressed air supply to the piston in order to power it during both its forward and reverse strokes and thus create an even more powerful sound. The entire horn apparatus was driven by a compressor.

Diaphoneme

A diaphoneme is an abstract phonological unit that identifies a correspondence between related sounds of two or more varieties of a language or language cluster. For example, the vowel that constitutes the English word eye is pronounced differently depending on dialect ([aɪ̯] or [ʌɪ̯] in RP and General American, [ae̯] or [əi̯] in Scottish English, [ɑɪ̯] in Australian English, [ɔɪ̯] in Irish English, [aː] in South African English, and [aː] or [əi̯] in Southern American English, etc.) but, in the appropriate context, all of these variants are perceived by speakers as equivalent, and thus constitute a single diaphoneme. The word diaphone was originally used with the same meaning, but was later repurposed to refer to any of the particular variants, making the relationship between diaphoneme and diaphone analogous to that between phoneme and allophone.

Diaphonology studies the realization of diaphones across dialects, and is important if an orthography is to be adequate for more than one dialect of a language. In historical linguistics, it is concerned with the reflexes of an ancestral phoneme as a language splits into dialects, such as the modern realizations of Old English /oː/.

Diaphone (moth)

Diaphone is a genus of moths of the Noctuidae family.

Species

References