Philip Glass’ ability to draw an audience of massively varied age groups is impressive. The event in question, which ran for two nights, certainly addressed the Edinburgh International Festival 2013’s theme of how artists engage with technology.

The starting point in the process was Jean Cocteau’s 1946 film La Belle et la Bête (“Beauty and the Beast”), based on the fairy-tale by Jeanne-Marie Leprince de Beaumont. Glass created his opera/film by removing the dialogue and Georges Auric’s original film score, and then composing music for six-piece ensemble and four singers, tasked with the challenge of singing the original French dialogue. Such are the differences between the rhythms of spoken and sung language that the intention can surely never have been perfect lip-synching. However, the outcome was amazingly close to that and all the more impressive for the absence of headphones, click-tracks and the like. The impressive timing was the result of Glass’ score and Michael Riesman’s conducting. In his own programme note, Glass confessed that, without previous experience of scoring films, he “would not have attempted it at all”. The musicians’ focus and stamina was laudable, providing a seamless score for the film’s 96-minute duration.

The plot has in common with Cinderella a pair of cruel, vain sisters. Despite her positive name, Belle is effectively the family servant, the household also featuring her father and brother. Avenant, Belle’s suitor, is never far.

Straying into La Bête’s lair when lost, Belle’s father plucks a rose for her. This near-fatal flaw results in a choice: death, or a daughter taking his place – not in death but in possible life with the beast. Belle steps up. Being of good heart, she comes to no harm but shrinks from repeated offers of marriage to the beast who, we discover, is also essentially of good heart. Her return from compassionate leave coincides with Avenant’s bid to slay the beast. Avenent is shot down by a talented statue and the beast assumes his form. Happiness ensues.

I was intrigued to read later (and can’t claim to have divined at the time) that the father’s visit to the beast’s domain represents that part of the creative process where the artist delves into the unconscious. I was reminded of many Hammer House of Horror moments where hospitality and harm go hand in hand: doors magically open; candelabra are extended by living arms through portholes in the walls; drinks are served by disembodied hands. Unlike traditional horror movies, this tapping of the unconscious felt like it could go either way, rewarding the venturer with either enrichment or derailment. I should point out the film also contains many humorous moments and there was great mirth in the audience.

But what of the music? The performance appeared to be immaculate. The singers gave committed and dramatic portrayals. Hai-Ting Chinn, in the near-omnipresent role of Belle, put across the warmth of a character happier to serve others than to seek personal happiness. Marie Mascari conveyed the greed and vanity of both sisters without straying near the penny-dreadful villain. Peter Stewart was very convincing across both generations of Belle’s male relatives – a loving, if not self-sacrificing father and a loveably roguish brother. Gregory Purnhagen, his palate of roles the most widely varied, furnished a conflicted Bête, an enamoured Avenant, and two other characters too. I would venture to suggest that many in the audience would be so taken with the subtitled film as to be unaware of the provenance of every sung line. The singers’ black clothes and concert performance delivery suggest that this was the intention.

My problem was the music itself: a couple of passages of genuinely puzzling meter aside, regular pulse reigned; despite the harmonic surprise of some “unrelated chords”, genuine key-threatening chromaticism seemed absent. I certainly don’t have a problem with Glass’ preference for undeveloped themes, in the western symphonic sense of the word.

What I struggle with is the preponderance of triads. These three-note building blocks of western harmony, when adulterated by neither addition nor subtraction, soon bore me. I don’t even require triads to be present at all; I’m happy to go with pretty much any combination of sounds. But, I’m quickly wearied by the simple triad’s confining lack of ambition and surprise, and I can’t buy the notion that they avoid distraction from the film, because they certainly distracted this listener, not least in their inability to reflect the film’s narrative arc. Had the instrumental line-up been more varied than three keyboards and three wind instruments (all magnificently played) would this have made a difference? I don’t think so. It’s simply some kind of musical dietary deficiency in me. I seem to require supplements, or fasting. Nevertheless, I enjoyed the overall experience, and the audience loved it.