Period-instrument performance has been around for decades, but has really exploded in the last 15-20 years. A few groups popped up as early as the 50's and 60's, but the 70's is when it began to really gain traction.
On the website for the Handel and Haydn Society, they lay it out like this:
"In the 1970s, people started to ask why works were being performed on instruments that hadn’t been available to the artists who composed them. For instance, the keyboard Bach used was different from the one used by Mozart, and in turn the one used by Mozart was very different from that of Beethoven. In order to appreciate the intended effects of their works, it made sense that they be performed on the instruments for which they were written."
On the other hand, composers were constantly updating music from the past to be performed on new instruments or in a new way. Mozart reworked Handel's Messiah, Bach made arrangements of Vivaldi's music, Stokowski did the same with Bach's music. It IS fun to hear new treatments of past compositions. It is also helpful to have some context as to what the piece was originally like.
Writing for Deceptive Cadence on NPR's website, Tom Verde dug into the subject of how modern technology might further the art and science of original instrument performance.
Sina Shahbazmohamadi, is director of imaging at UConn's Center for Clean Energy Engineering, as well as an associate professor of mechanical engineering at Manhattan College in the Bronx. What does he have to do with period instruments? Enter Robert Howe, who collects antique wind instruments. Along with his work as a reproductive endocrinologist and M.D. and UConn, he is a Ph.D. candidate in music history and theory. When he met Prof. Shahbazmohamadi, a light went off.
Howe owns a number of saxophones manufactured by Adolphe Sax, the instruments inventor. There are very few of the original mouthpieces for his instruments. In order to hear how a saxophone from the mid-19th century would have sounded, you should really use an original mouthpiece. They are so fragile, that is not possible. However, Howe had the idea that "CT scans, X-rays and similar medical technology might also be used to examine the anatomies of antique oboes, flutes and saxophones." Below is one of the very earliest of Sax's instruments from Howe's collection.
https://www.youtube.com/watch?v=d0EoCY8Dl1M
As the two conferred, Shahbazmohamadi thought it might be possible to use the x-ray and CT scan information to build perfect reproductions of the mouthpieces.
https://www.youtube.com/watch?v=iGLRRfvjynU
The research is fascinating. Who knows how it may change the manufacture of musical instruments in the future? In the meantime, music written for Adolphe Sax's invention is being heard in a way not possible in nearly 100 years.
Learn more about the history and evolution of the saxophone in a video produced by the Saxquest Saxophone Museumin St. Louis.
https://www.youtube.com/watch?v=vUieJ2HS_kg