Suzuki method

[Eine Alpensinfonie]

Are these unfortunates unable to sing well at the top of their range, or is it "merely" a problem with their perception? Would a bit of additional vocal training help?

Don’t get me wrong. Our sopranos are excellent in many ways. The tuning problem might not exist if the otherwise exemplary MD did something about it.
My theory is that whenever the vocal line ends a phrase dropping from the submediant to the dominant (6th degree of the scale to the 5th) they fall in pitch slightly too far. As the dominant is a very strong part of the harmony, it then results in a new flatter tonic (key note). The longer the piece, the worse it gets.

[Ein Heldenleben]

I’m only thinking of those sopranos in the choir I’m in, dragging the whole ensemble progressively flatter. Thinking about intervals via scales could be extremely beneficial.

In the choir my wife is in one of the warm ups introduced by the very experienced singing trainer was to get them to sing a chromatic scale . I have no problem singing major and minor scales but chromatic - that’s really really hard .
A musician friend of mine once said he thought tuned percussion (e.g. timps) were terrible for throwing choirs out of tune . Other problems - inaudible (or worse out of tune ) organs, the sops not being able to hear the basses , or the orchestra; or one or two people who can sing (often loudly ) but not quite in tune.
I once went to a choral evensong and naively asked my wife why the conductor kept pointing upwards - was he ,I wondered , asking them to draw greater inspiration from the Almighty ?
I can still hear the laughter !

Singers I’ve never heard out of tune - Ella Fitzgerald , Nat King Cole , Mel Tormé, the young Paul McCartney.

Singers perhaps more “challenged” Frank Sinatra, Tony Bennet, the latter years of Paul Mc ?

[Ein Heldenleben]

Don’t get me wrong. Our sopranos are excellent in many ways. The tuning problem might not exist if the otherwise exemplary MD did something about it.
My theory is that whenever the vocal line ends a phrase dropping from the submediant to the dominant (6th degree of the scale to the 5th) they fall in pitch slightly too far. As the dominant is a very strong part of the harmony, it then results in a new flatter tonic (key note). The longer the piece, the worse it gets.

Re that interesting point - would it make a difference if they could hear the basses presumably striking the root of the chord ? Sometimes in big choirs they are so far from them they can’t hear the bass line .