Voice-leading in Bach chorales: Passing sevenths
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What's the problem with passing sevenths?
Adding a passing seventh to a perfect cadence is an excellent way of making it sound like Bach (see cadential fingerprint resources for more on characteristic Bachian touches). There are some very common mistakes that students make with adding passing notes at cadences that you need to be careful to avoid.
How can I avoid making mistakes?
The most common problem is adding the wrong passing note at the cadence. As shown in the example below, it is often possible to add a passing note to either of the inner parts at a cadence.
The correct passing note, however, is the one that makes seventh above the root of chord V. This creates a dominant seventh, which strengthens the cadence - the other passing note adds a passing ninth, which is much less characteristic (and for which you will not get a mark in your A level exam!).
You also need to be careful of is if the third of the final chord of a perfect cadence is already in the soprano part. The passing seventh must fall by step and this is impossible to achieve without doubling the third if it is in the soprano part already.