Stroh violin, or Strohviol, (Romanian: Vioara cu goarnă) is a trade name for a horn-violin, or violinophone—a violin that amplifies its sound through a metal resonator and metal horns rather than a wooden sound box as on a standard violin. The instrument is named after its designer, John Matthias Augustus Stroh, an electrical engineer in London, who patented it in 1899. The Stroh violin is also closely related to other horned violins using a mica sheet-resonating diaphragm, known as phonofiddles.
In the present day, many types of horn-violin exist, especially in the Balkans.
Description and background 
Stroh violins are much louder than a standard wooden violin, and its directional projection of sound made it particularly useful in the early days of phonographic recording. As regular violins recorded poorly with the old acoustic-mechanical recording method, Stroh violins were common in recording studios, but became rarer after record companies switched to the new electric microphone recording technology in the second half of the 1920s. While the Stroh produces significantly more volume, it does this at the expense of tone, offering a sound that is harsher and more grating than a standard violin. On early records the Stroh violin can be recognized by its characteristically thin whining tone.
The Stroh violin was an expensive instrument: in 1911 it was offered by the London dealers Barnes & Mullins for nine guineas (£9.45, then equal to $37.80) or twelve guineas (£12.60 / $50.40) at a time when a reasonable factory violin could be had for two guineas. It was listed as being especially suitable for use in small theaters and music-halls. There was also a Stroh viola.
Current usage 
A number of musicians, including Tom Waits, Carla Kihlstedt, Thomas Newman, Bat For Lashes, A Hawk and A Hacksaw  and Eric Gorfain  continue to use the Stroh violin for its distinctive sound. Shakira featured a Strohviol on her 2010/11 The Sun Comes Out World Tour, with multi-instrumentalist Una Palliser playing it on some songs. Pinky Weitzman plays the Stroh violin for various New York experimental ensembles, including her own project (Not Waving But Drowning), as well as Flare, LD & the New Criticism, and as part of the onstage ensemble for Stephin Merritt's My Life as a Fairy Tale. A Stroh violin is regularly played by Andy Stein of Vince Giordano's Nighthawks, a New York based band specializing in the music of the 1920s and 1930s.
The Stroh violin is used in folk music of the Bihor region of Romania. Famous practitioners of this music style include fiddler Gheorghe Rada, singers Florica Bradu, Florica Ungur, Florica Duma, Leontin Ciucur, Cornel Borza, Vasile Iova, Maria Haiduc, Viorica Flintasu, and renowned folk ensembles Crisana or Rapsozii Zarandului. In 1920s Buenos Aires, Julio de Caro, a renowned Tango orchestra director and violinist, used it in his live performances, and was called violín-corneta (cornet violin) by the locals.
Romanian horn-violin 
The Romanian horn-violin is similar to the Stroh violin. It was built through the 20th century. It has the same length as the Stroh violin, but its horn is narrower and yields a more directional sound. The structure of the instrument is based on the element of an old-fashioned gramophone. Amateurs or small workshops could easily build it and, perhaps for that reason, many variants exist in Eastern Europe.
The vibrations of the strings and bridge are transmitted by a thin rod to the membrane of the gramophone-element. The membrane transforms these vibrations into sound waves, which are amplified by the horn or beaker. The horn-violin is harder to play than a normal violin because the reaction of the bow on the strings is less flexible, and the instrument's weight is less evenly distributed. This causes an imbalance on the shoulder.
The instrument is still used in Romanian folk-music for playing horas and doinas, and mixes well with the characteristic sound of the pan-flute. It is generally used sparsely as the grating tone can irritate after a while. Instruments like the Stroh violin and other types of horn-violin remain a curiosity; they are quite rare in the orchestra.
See also 
- John Matthias Augustus Stroh "electrical engineer, of Haverstock Hill in the county of London", British Patent No. 9418 of 1899, applied for 4 May 1899, accepted/published 24 March 1900
|Wikimedia Commons has media related to: Stroh violins|
- Smithsonian Institution HistoryWired article about the Stroh violin (includes photos)
- Digital Violin - Article considering the context of Stroh and other related Horn Violins
- YouTube Video - Louise played on the Stroh Fiddle (Violin) by Corwin Zekley
- Video - Siperkov plays the horn-violin
- The violinophone is one of the interesting Instruments of Amazonas