Bach, music and his life vs Mattheson Duet Sonatas Utilisation & Stats

Mattheson's duet sonata practice app. Contains 4 sonatas. SONATA Ⅰ(Op.1.Nr.1), SONATA Ⅱ(Op.1.Nr.2), SONATA Ⅲ(Op.1.Nr.11), SONATA Ⅳ(Op.1.Nr.12) You can play each part, change the speed, and change the pitch (440Hz and 414Hz), so you can practice according to your situation. It’s Sounds quite real because it is a sampled sound source.