The shoulder rest is an accessory that can be found on violin

Violin

The violin is a string instrument, usually with four strings tuned in perfect fifths. It is the smallest, highest-pitched member of the violin family of string instruments, which includes the viola and cello....

s and viola

Viola

The viola is a bowed string instrument. It is the middle voice of the violin family, between the violin and the cello.- Form :The viola is similar in material and construction to the violin. A full-size viola's body is between and longer than the body of a full-size violin , with an average...

s. It may be made of wood, aluminium, carbon fiber

Carbon fiber

Carbon fiber, alternatively graphite fiber, carbon graphite or CF, is a material consisting of fibers about 5–10 μm in diameter and composed mostly of carbon atoms. The carbon atoms are bonded together in crystals that are more or less aligned parallel to the long axis of the fiber...

 or plastic. Usually, the shoulder rest attaches to the edge of the back of the violin

Violin construction and mechanics

A violin consists of a body or corpus, a neck, a bridge, a soundpost, four strings, and various fittings. The fittings are the tuning pegs, tailpiece and tailgut, endpin, possibly one or more fine tuners on the tailpiece, and perhaps a chinrest, either attached directly over the tailpiece or to the...

 with "feet" padded with rubber tubing or made of soft plastic. The goal of a shoulder rest is to allow a more comfortable attitude while playing by adding height to the shoulder and preventing the instrument from slipping (Kreitman, p. 30). A shoulder rest generally follows the curve of the shoulder; some shoulder rests are bendable, others are made of sponge-like material, and a few have an extension that hooks further over the shoulder for stability. It is a relatively recent invention, and though it is quite commonly used among modern violinists and violists, it is not universally used. Depending on body type and style of clothes, some musicians need no more than a thin sponge, a cloth or sometimes nothing at all under the instrument.

Merits and Demerits

There are two common approaches to playing without a shoulder rest. The first is to hold the violin horizontal with the support of the left hand at all times. This usually decreases the mobility of the thumb during downshifts and requires the thumb never to leave the neck of the violin in order to support the instrument. The second approach is to support the instrument almost fully at the neck-shoulder region, often requiring the use of some form of padding beside the collar bone to bring the violin closer to the jaw and to hold the instrument in place. Some violinists may even raise their shoulder to achieve this, particularly when shifting positions and when using vibrato

Vibrato

Vibrato is a musical effect consisting of a regular, pulsating change of pitch. It is used to add expression to vocal and instrumental music. Vibrato is typically characterised in terms of two factors: the amount of pitch variation and the speed with which the pitch is varied .-Vibrato and...

. Problems frequently surface while doing this, such as constant muscle tension which obstructs fluidity of technique, and may lead to injury in the long term. These problems can also arise from incorrect usage of shoulder rests.

A shoulder rest can dampen the instrument's tone by decreasing the vibrations of the back of the instrument. According to the renowned violin

Violin

The violin is a string instrument, usually with four strings tuned in perfect fifths. It is the smallest, highest-pitched member of the violin family of string instruments, which includes the viola and cello....

ist and professor

Professor

A professor is a scholarly teacher; the precise meaning of the term varies by country. Literally, professor derives from Latin as a "person who professes" being usually an expert in arts or sciences; a teacher of high rank...

 Leopold Auer

Leopold Auer

Leopold Auer was a Hungarian violinist, teacher, conductor and composer.-Early life and career:...

, the use of a shoulder rest could take away more than one-third of the violin's natural volume; although more recent scientific studies prove it to be substantially less. The shoulder alone can also hinder the instrument's tone if it is pressing against the back of the instrument. Many great violinists, including Tibor Varga, Aaron Rosand

Aaron Rosand

Aaron Rosand is an American violinist.Born in Hammond, Indiana, he studied with Leon Sametini at the Chicago Musical College and with Efrem Zimbalist at the Curtis Institute of Music, where he has taught since 1981...

, Anne-Sophie Mutter

Anne-Sophie Mutter

Anne-Sophie Mutter is a German violinist.- Early life :Mutter was born in Rheinfelden, Germany. She began playing the piano at age five, and shortly afterwards took up the violin, studying with Erna Honigberger, a pupil of Carl Flesch...

, Jascha Heifetz

Jascha Heifetz

Jascha Heifetz was a violinist, born in Vilnius, then Russian Empire, now Lithuania. He is widely regarded as one of the greatest violinists of all time.- Early life :...

, Nigel Kennedy

Nigel Kennedy

Nigel Kennedy is a British born violinist and violist. He made his early career in the classical field, and he has performed and recorded most of the major violin concerti...

, Nathan Milstein

Nathan Milstein

Nathan Mironovich Milstein was a Russian-born American virtuoso violinist.Widely considered one of the finest violinists of the 20th century, Milstein was known for his interpretations of Bach's solo violin works and for works from the Romantic period...

, Itzhak Perlman

Itzhak Perlman

Itzhak Perlman is an Israeli-born violinist, conductor, and instructor of master classes. He is regarded as one of the pre-eminent violinists of the 20th and early-21st centuries.-Early life:...

, Pinchas Zukerman

Pinchas Zukerman

Pinchas Zukerman is a world-renowned violinist, violist, and conductor. He is considered one of the greatest violinists of the 20th and 21st centuries, and his ongoing 45-year career has seen him perform with the world's best-known orchestras and record over 100 works...

, Michael Rabin

Michael Rabin

Michael Rabin may refer to:*Michael O. Rabin , computer scientist*Michael Rabin...

, Fritz Kreisler

Fritz Kreisler

Friedrich "Fritz" Kreisler was an Austrian-born violinist and composer. One of the most famous violin masters of his or any other day, he was known for his sweet tone and expressive phrasing. Like many great violinists of his generation, he produced a characteristic sound which was immediately...

, Efrem Zimbalist

Efrem Zimbalist

Efrem Zimbalist, Sr. was one of the world's most prominent concert violinists, as well as a composer, teacher, conductor and a long-time director of the Curtis Institute of Music.-Early life:...

, Isaac Stern

Isaac Stern

Isaac Stern was a Ukrainian-born violinist. He was renowned for his recordings and for discovering new musical talent.-Biography:Isaac Stern was born into a Jewish family in Kremenets, Ukraine. He was fourteen months old when his family moved to San Francisco...

, and Eugène Ysaÿe

Eugène Ysaÿe

Eugène Ysaÿe was a Belgian violinist, composer and conductor born in Liège. He was regarded as "The King of the Violin", or, as Nathan Milstein put it, the "tzar"...

, have not used a shoulder rest.

Some instruments have been marked due to the friction on the wood and added tension to the instrument the shoulder rest may bring according to each different player strength.

A Shoulder rest, whatever its design, is an accessory to facilitate holding the violin. This can lighten the task of the left hand, enabling smoother and lighter shifting technique. All rests must make a compromise between violin support and freedom (or flexibility in holding the violin). There are a number of soft rests (generally anatomy friendly) and harder or rigid rests on the market.