What is this notation in Debussy's "Engulfed Cathedral"?

Question

In light of the recent portato question at What do the dots and lines underneath these chords mean?, what did Debussy mean by the tied portato on the third quarter note of the second measure of Debussy's La Cathédrale engloutie?

On one hand, portato on the piano indicates a slight re-articulation of the pitch. If that's the case, then why is there a tie between the two Gs, apparently telling us not to re-articulate?

The situation becomes stranger when we hear Debussy himself perform this (via a piano roll); he does not re-articulate this G.

What is the point of the dot above this G?

For anyone curious, the three separate scores on IMSLP all have this exact same notation.

Answer 1

As the Guest answer said, it's simply a tied note indicating the local meter is 6/4, as the tied quarter notes commonly represent a rhythm that shows the second primary beat in a 6/4 bar. (Note ties used in a similar fashion for that rhythm in the left hand in mm. 14-15 later, as well as a tied half to quarter in m. 6. All of these clearly indicate a 6/4 meter in those bars.)

I would only disagree with that answer saying it makes no "practical difference" in bar two, as it clearly implies a different "feel" for the rhythm in that bar. Debussy wrote this piece intending the meter to go back and forth between 3/2 and 6/4. If he had written the last two notes of the second bar as half notes, the meter would appear to be 3/2, and those notes would be felt "on the beat." As they are written with the tie, the rhythm is syncopated and neither of those notes is "on a beat." The practical interpretation for a performer is that the notes will not be played "straight" with a metric accent, but instead should feel "off-beat," which will likely affect microtiming of the rhythm (as well as affecting articulation/dynamic, as the notes do not line up with metric accent) in that bar.

Answer 2

There is nothing really to explain here. Articulations on tied notes are not very common, but they don't mean anything different from articulations on non-tied notes. There are different opinions about whether the articulation should be written on the first or second note of the tie, but in a published score that decision has already been made.

The reason for writing two tied quarter notes instead of one half note is simply to reinforce the fact that the initial time signature is 6/4 (two groups of three) not 3/2 (three groups of two). That doesn't make much practical difference to bar two, but it does make a difference to the way the quarter notes in bars 1 and 3 are accented.

The initial time signature shows both alternatives, which sidesteps someone thinking that the tempo relationship between 6/4 and 3/2 might be "dotted half note = half note" rather than "quarter note = quarter note" if the time signature changes were marked where they occurred. On the first page, the rhythmic notation shows there is a change to 3/2 at bar 7, and back to 6/4 at bar 13.

Answer 3

Debussy's piano music is written for a grand piano. Without the sostenuto pedal (the middle one) the quoted bars can't be played quite as he intended, though you can get close!

On the first beat of the second bar the pianist presses the sostenuto pedal. That holds ('sustains') the notes which are already sounding: the low G-D-G, plus the five-note chord E-A-E-A-E which has just been played. (The ties on all these show they are to be sustained.)

Although the sostenuto pedal is now held down until the end of the bar, it doesn't sustain any of the notes played in bar 2! That's the brilliant thing about the sostenuto pedal. Only the notes which were already sounding at the precise moment the pedal was depressed get sustained. It has no effect on notes played afterwards: staccato notes SOUND staccato! Once it's pressed no new notes get added to that sustained group. This is not at all what happens with the sustain pedal of a two-pedal upright piano!

AND of course while the sostenuto pedal is down you still have the normal sustain pedal (and the soft pedal) available, so the markings on those three LH notes really can be observed.