Performance Record of J.S. Bach – Invention No. 9 in F Minor, BWV 780

A performance record of Bach's Invention No. 9 (BWV 780), recorded in June 2025 by Reiji at age 9. In this rendition, Reiji offers a nuanced interpretation of harmonic rhythm, structural modulation, and overtone mapping—identifying shifts in tonality with precise fractional cadence tracking. This document includes detailed personal insights and acoustic observations.

Reiji's Observations

Although this piece is written in 3/4 time, I felt that the harmonic rhythm moves with a 2/4 pulse.
In other words, the beat accents flow like “1-2-3 / 1-2-3,” but the harmonic tension feels like “*1–2–*3 / 1–*2–3,” which gave me a unique sense of meter. I performed it with that feeling in mind.

I was also struck by the frequent modulations.
The home key is F minor (Fm), but the tonal center shifts several times as follows:

• 0.5th modulation: G minor (Gm) — I counted it as 0.5 because there is no clear cadence.
• 1st modulation: C minor (Cm)
• 1.25th modulation: B-flat minor (B♭m)
• 1.5th modulation: A-flat major (A♭M)
• 1.75th modulation: D-flat major (D♭M)
• 2nd modulation: Return to F minor (Fm)

I counted modulations with clear cadences as “1,” and intermediate tonal shifts without cadence as fractional steps like 0.5 or 1.25.
In this way, I interpreted the piece as modulating six times, which gave me the impression that it allows for a wide expressive range.

One particularly memorable moment was in bar 24, where the key shifts from F minor to A-flat major, its relative major.
The melodic line and harmonic shift work together to produce a very beautiful effect.

Additionally, this piece has a rich overtone structure.
For example, in bar 31, the low C2 can resonate up to the 64th overtone, and in bar 14, the high C6 produces downward partials up to the 39th overtone.
This makes it an excellent piece for practicing overtone control.

* These are personal reflections by the performer.