<P> During the Medieval period the foundation was laid for the music notation and music theory practices that would shape Western music into the norms that developed during the common - practice era, a period of shared music writing practices which encompassed the Baroque music composers from 1600--1750, such as J.S. Bach and Classical music period composers from the 1700s such as W.A. Mozart and Romantic music era composers from the 1800s such as Wagner . The most obvious of these is the development of a comprehensive music notational system which enabled composers to write out their song melodies and instrumental pieces on parchment or paper . Prior to the development of musical notation, songs and pieces had to be learned "by ear", from one person who knew a song to another person . This greatly limited how many people could be taught new music and how wide music could spread to other regions or countries . The development of music notation made it easier to disseminate (spread) songs and musical pieces to a larger number of people and to a wider geographic area . However the theoretical advances, particularly in regard to rhythm--the timing of notes--and polyphony--using multiple, interweaving melodies at the same time--are equally important to the development of Western music . </P> <P> Many instruments used to perform medieval music still exist in the 21st century, but in different and typically more technologically developed forms . The flute was made of wood in the medieval era rather than silver or other metal, and could be made as a side - blown or end - blown instrument . While modern orchestral flutes are usually made of metal and have complex key mechanisms and airtight pads, medieval flutes had holes that the performer had to cover with the fingers (as with the recorder). The recorder was made of wood during the Medieval era, and despite the fact that in the 2000s, it may be made of synthetic materials, it has more or less retained its past form . The gemshorn is similar to the recorder as it has finger holes on its front, though it is actually a member of the ocarina family . One of the flute's predecessors, the pan flute, was popular in medieval times, and is possibly of Hellenic origin . This instrument's pipes were made of wood, and were graduated in length to produce different pitches . </P> <P> Medieval music used many plucked string instruments like the lute, a fretted instrument with a pear - shaped hollow body which is the predecessor to the modern guitar . Other plucked stringed instruments included the mandore, gittern, citole and psaltery . The dulcimers, similar in structure to the psaltery and zither, were originally plucked, but musicians began to strike the dulcimer with hammers in the 14th century after the arrival of new metal technology that made metal strings possible . </P> <P> The bowed lyra of the Byzantine Empire was the first recorded European bowed string instrument . Like the modern violin, a performer produced sound by moving a bow with tensioned hair over tensioned strings . The Persian geographer Ibn Khurradadhbih of the 9th century (d . 911) cited the Byzantine lyra, in his lexicographical discussion of instruments as a bowed instrument equivalent to the Arab rabāb and typical instrument of the Byzantines along with the urghun (organ), shilyani (probably a type of harp or lyre) and the salandj (probably a bagpipe). The hurdy - gurdy was (and still is) a mechanical violin using a rosined wooden wheel attached to a crank to "bow" its strings . Instruments without sound boxes like the jaw harp were also popular . Early versions of the pipe organ, fiddle (or vielle), and a precursor to the modern trombone (called the sackbut) were used . </P>

Who was the composer known for altering music between two groups of voices or instruments