A soft, sustained high note floats over a musical texture. The music moves on underneath (slow, sad, troubled, tense - anything but happy examples) while the high note continues, insistently. Help me (re)find examples of this trope in pieces of classical music and solve something that's been needling me for a long time.
10-15 years ago I heard someone describe this particular compositional technique with reference to a musical example, and then heard the piece in context - which with that setup was very, very moving. I've had an ear out for the trope ever since, but have never been able to find what the original piece I heard analysed was. (My memory says this was part of a BBC documentary, but that might neither be here nor there.)
It's an extremely effective technique and used a lot in music for film and TV - imagine the soundtrack to a crime thriller at a point where someone is quietly about to discover something shocking, and how the music keeps you absolutely still and on edge until the story's next moment.
The high note is usually strings, sustained or very quiet tremolo. High woodwinds are also an option, though. Musically, the note functions as an extreme inverted pedal note
to any harmonic movement underneath it and lasts for at least several bars. It's chilling, plaintive, eerie.
The d′ ′ ′ pedal at the beginning of RVW's Fantasia on a Theme by Thomas Tallis
is very near to this (but shifting between eerie and sublime!). The e♭′ ′ (′ ) octaves which persist through most of the first five minutes of part II of Mahler 8
are definitely one example, on a very large scale.
I have a feeling I'm looking for small-ensemble music - quartets, chamber ensembles - but orchestral pieces or even choral (the 'floaty far-off angelic soprano note' effect) also count. Can you help me track down these pieces, and maybe even hit on the original which got me searching?