We hear about “performance practice” a lot from early music groups. What does that actually mean in practical terms during the late 19th century? Here is a brief list:
Tempo modification: performers make contrasts of tempos, even when not written in the score by the composer.
Gut strings: the core of the string is made from gut. Modern strings have a metal or synthetic core. Gut strings have a different response, and have a richer overtone series.
Vibrato: Generally less vibrato than in modern playing. The celebrated violinist, Joachim, used practically no vibrato, while the cellist in his string quartet did use some. The introduction of metal strings (particularly the top E string of the violin) coincided with the rapid rise in use of constant vibrato, because players missed the richness of the old gut strings and were compensating with vibrato.
Bowing: 19th century string players knew how to employ very slow bows – they didn’t “split” the bowing as much as is done now. Of course that means the result may be softer.
Portamenti: This means sliding between the notes. This went out of fashion during the 2oth century, but earlier generations enjoyed this effect – it may be done lightly and discreetly not necessarily in the syrupy old Hollywood style.
Rubato: fluctuation of the tempo within the phrase – one simple device is making an accelerando in crescendo passages, and slowing down in diminuendi.
Agogic: this means holding just a single note of a phrase for a bit longer than written. Brahms’ violinist, Joachim, was said to have brought this style of performance to a high degree of perfection. The note is not necessarily played any louder.
Dislocation: this means strands of the music do not have to be exactly synchronised; the melody may be played with a greater degree of freedom than the accompanying parts. Pianists mostly played with hands not quite together, often the left hand first, but also the other way around. “Modern” performances are typically exactly together.