This App is a collection of the four-part Chorales harmonized by Johann Sebastian Bach. When first launched, the Chorale numbered to the current day of year is shown. You can then choose any of the 371 Chorales with the "Select Wheel" found on the second screen.
When the "Figured Bass Switch" is activated the alto and tenor voices are removed and figured bass is added. This highlights the harmony and simplifies the music, making it more accessible.
The "Transpose Wheel" on the right shows the number of half-steps you have chosen to transpose the Chorale from it's original key (displayed on the left). Practicing in all twelve keys is ideal.