I Don't Know Why by Roy Turk

Overview

Key: B♭ major · Chords used: 10 · Sections: 3

Form: Intro → A Section → B Section

Where these chords come from: a chord chart of this song written by a musician and shared on the iReal Pro forums, archived in the iReal Pro forum charts archived in ChoCo (de Berardinis et al., 2023). It's one musician's reading of the song, not a transcription checked against the recording. This page shows that chart as-is: the analysis below is generated directly from it by code, not written by AI. Consecutive repeats of a chord are shown once, and the piano voicings are our playable arrangement of each chord symbol, not a note-for-note transcription.

Section by section

Intro

• B♭ – G7 – Cm7 – F7 – B♭ – F7
  I – VI7 – ii7 – V7 – I – V7

A Section

• B♭ – B♭6 – Dm7 – Edim
  I – I6 – iii7 – #iv°
• Cm7 – F7 (×2)
  ii7 – V7
• B♭6
  I6

B Section

• B♭/A♭ – G7 – C9 – F7 – B♭ – C7 – Cm7 – F7 – B♭ – G7 – Cm7
  I (bass A♭) – VI7 – II9 – V7 – I – II7 – ii7 – V7 – I – VI7 – ii7
• F7 – B♭ (×2)
  V7 – I
• G7 – Cm7 – F7 – Dm7 – G7 – Cm7 – F7 – B♭
  VI7 – ii7 – V7 – iii7 – VI7 – ii7 – V7 – I

Chord vocabulary

Chord	Roman numeral	Role	Heard in
B♭	I	Home chord (tonic)	Intro, A Section, B Section
G7	VI7	Secondary dominant (V/ii)	Intro, B Section
Cm7	ii7	In the key	Intro, A Section, B Section
F7	V7	In the key	Intro, A Section, B Section
B♭6	I6	Home chord (tonic)	A Section
Dm7	iii7	In the key	A Section, B Section
Edim	#iv°	Outside the key (chromatic)	A Section
B♭/A♭	I (bass A♭)	Outside the key (chromatic)	B Section
C9	II9	Secondary dominant (V/V)	B Section
C7	II7	Outside the key (chromatic)	B Section

Harmonic highlights

• G7 acts as V/ii: it resolves to Cm7.
• C9 acts as V/V: it resolves to F7.

Sources & accuracy

• Chords: the iReal Pro forum charts archived in ChoCo (de Berardinis et al., 2023). Community chord chart “I Don't Know Why (I Just Do)” (credited “Roy Turk, Fred Ahlert”, style Latin mm120) from the forum file linked here, CC BY 4.0 via ChoCo. Performer/songwriter confirmed from Wikidata.
• Section names: from the chart's own markings: section names written on the chart (Intro, Verse, Chorus…) are kept, and rehearsal letters are shown as “A Section”, “B Section” and so on (the B of an AABA song is called the Bridge).
• Cross-check: the iReal Pro forum charts archived in ChoCo (de Berardinis et al., 2023). Community chord chart “I Don't Know Why [I Just Do] (Beloff arr.)” (credited “Fred E. Ahlert, Roy Turk”, style Ballad - Melodic) from the forum file linked here, CC BY 4.0 via ChoCo. Performer/songwriter confirmed from Wikidata. A separately posted chart of the same song; its chords match this page's closely when both are read in the same key (similarity 70%).
• Chord charts are often written in a key that suits a particular singer or band, so this may not be the key of the original recording.
• About the song: Wikipedia.
• Verified: two community charts of this song, posted in different forum threads, agree on its harmony. They're still charts, not transcriptions checked against the recording.
• Rhythm and chord durations aren't shown; each step is one chord change.