What are Period Instruments?
Period instruments - are musical instruments which have been made in the same way that they were hundreds of years ago so that old music will sound like it used to when it was first composed.
Musical instruments have changed a lot during the last few centuries. Composers like Johann Sebastian Bach wrote music for instruments which sounded different from the way they do today. Although most of the orchestral instruments we use nowadays were already in use in Bach’s day, instrument makers have made changes to them. These changes often gave the instruments a bigger sound so that they could be heard well in big concert halls. Orchestras also got bigger and bigger.
During the 20th century musicians started to realize that the way we play the music of Bach and other composers from the past was making the music sound rather different from the way it would first have been heard. People became interested in hearing what the music would have sounded like back in the 17th and early18th centuries (the Baroque period). Very few of the old instruments still existed and those that had survived had been “modernized”. So instrument makers started to make instruments in the old ways. Some musicians and orchestras started to play these instruments. The instruments are often called “period instruments” (or "authentic instruments" or "historical instruments") because they are made so that they are like instruments of older periods of history.
Pitch - In 1939, modern orchestras agreed to tune to a’=440hz (the note A pitched at 440 cycles per second), which replaced a previously lower pitch (a’=435hz) adopted in 1859. Before 1859, however, there was no pitch standard. The note to which baroque ensembles tuned, therefore, varied widely at different times and in different places. As a result, the music notated on a score might have sounded as much as a half tone lower than how it would traditionally be performed today. In an effort to allow for this discrepancy, many baroque ensembles adjust their tuning to the repertoire being performed: a’= 415hz for late baroque music, a’=392hz for French music, a’=440hz for early Italian music and a’=430hz for classical repertoire.
Timbre - While most of the instruments in a baroque ensemble are familiar, there are several prominent members no longer featured in modern ensembles. The harpsichord was the primary keyboard instrument (and an important member of the continuo group), and instruments important in the 16th and 17th centuries like the lute and viol, still continued to be used. Variations in instruments still popular today also gave the baroque ensemble a different sound. String instruments like the violin, viola and cello used gut strings rather than the strings wrapped in metal with which they are strung today, for example, giving them a mellower, sweeter tone.
Performance technique - A baroque score contains little (if any) information about elements like articulation, ornamentation or dynamics, and so modern ensembles need to make their own informed choices before each performance. Mechanical differences between baroque and modern instruments also suggest that the older instruments would have sounded differently. Because baroque and modern bows are structurally different, for example, string players using modern bows often use a gentler attack on the string and crescendos and diminuendos on longer notes. 17th and 18th century performance treatises also imply that finger vibrato (a technique in which a string player rocks his or her fingertip on the string to enrich the tone) was used sparingly for expressive moments, while bow vibrato (an undulating movement of the bow) was generally preferred.