WHEN I was at music college, I dearly wanted to learn to play a rare early electronic instrument called the ondes Martenot. That career dream was thwarted by the fact I never managed to get close enough to actually try one in the flesh, but it turns out there is a small room at the Paris Conservatoire – where else? – that is home to the world’s most extensive collection of ondes Martenots. Herein reside seven of the glorious instruments, in various states of playability, but still: seven ondes. Being in their company makes me feel simultaneously giddy and guilty, like waiting years to see a wild cat then rounding a corner and meeting an entire nonchalant family.

My host here is Nathalie Forget, one of today’s leading ondistes and a featured artist at next weekend’s Tectonics festival in Glasgow. She shows me around like a protective mother, eyeing my water bottle (liquid and rare electronics: not an ideal mix) before switching on various instruments to see which one might “be in a good mood” on this given morning. An exquisite array of sounds emerge: astral swoops, angry grunts, whispered snippets of sad elegies. “Since the beginning,” she tells me proudly, "these instruments have had important fans. Messiaen, Varese, Murail. Composers in Japan and Canada. A lot of cinema and theatre makers. Pop singers. Jacques Brel, Radiohead, Kraftwerk. These ondes” – she surveys the room – “have experience in every kind of music.”

The ondes was invented by a French cellist, Maurice Martenot, who worked as a radio telegrapher during the First World War and saw the potential of using oscillating radio tubes to create sound waves via electronic pulses. He started making prototypes in 1915 but the instrument was officially born in 1928: a wonder of early electronics whose intangible, eerie-sweet voice captured the imagination of the age.

“At the beginning, the ondes had a lot of religious repertoire,” Forget explains. “It came to represent the voice of angels, most famously thanks to Olivier Messiaen. Some people found it impossible to believe in light and angels after the horrors of the war. But the composers who wrote for the ondes – they were still of mind that we should keep faith. The fact that electricity still had a magic aura also helped. It was something that many people were happy not to understand. Certainly Martenot felt there was a mystical quality about the instrument.”

It was often women who played the ondes. Martenot’s own sister Ginette was the original ondes virtuoso, producing huge amounts of vibrato and extravagant glissandos. Later Jeanne Loriod, sister-in-law to Messiaen, took up the mantel, and her name still emblazons the posters that decorate the small classroom at the Paris Conservatoire.

Meanwhile Messiaen himself wrote rapturous music for ondes ensembles (Oraison; Fete des belles eaux), for ondes and voices (Trois petites liturgies de la presence divine) and included no fewer than three ondes in the orchestration of his grand opera, Saint Francois d’Assise. By the 1950s, various of his students started to follow suit — including the spectralists Roger Tessier and Tristan Murail, who used the instrument to unveil the miraculous world of overtones and in-between tones.

Elsewhere, the sensuous, expressive voice of the ondes did not sit so well with mid-century modernists, especially given its associations of mystic, lurid Catholicism. The fierce iconoclast Pierre Boulez had worked as an ondist at the Folies Bergère cabaret at the start of his career, but later he denounced the instrument: too kitsch by miles. Even the great Loriod had trouble finding enough work in the 1960s and had to take a job in a laundry for five years to pay the rent.

Matters deteriorated in the 1970s with the arrival of the synthesiser and computer generated electronic music. When Martenot died in 1980, a legal struggle over patenting threatened the instrument to near extinction. “He refused to grant permission for it to be manufactured by anyone else,” Forget explains. “He was afraid the instrument would change. He wasn’t interested in money. He always had a spiritual vision for what the ondes should be.”

And yet, blu-tacked to the door of Forget’s classroom at the Paris Conservatoire, a list of names shows 14 current ondes students — a remarkably healthy enrolment for an instrument that nearly disappeared just a few decades ago. “Yes, the great ondes revival!” she grins, explaining several factors for the new uptake. Instrument are finally being manufactured again. “For younger generations, the old religious associations don’t matter so much,” she adds. “They are more interested in the ondes as a resistance fighter.”

Above all, she stresses a renewed socio-political relevance. “People are drawn to its fragility,” she suggests. “Because today, people are wary of bombast and power. Our society is broken. We need to admit our vulnerability and recognise that we can no longer pretend to be conquerors.”

Martenot was also the inventor of a holistic technique called Active Relaxation, also known as kinésophie, that teaches awareness of tension in the body. The instrument and the technique are not unrelated: to play an ondes well, Forget points out, you must first be in tune with yourself. “You must be sensitive and open to change. It’s a good lesson, non?”

Nathalie Forget performs Bernard Parmegiani’s Outremer (1969) and a new work by Pascale Criton, as well as hosting an ondes Martenot workshop. City Halls, Glasgow, May 5 & 6, part of the BBC Scottish Symphony Orchestra’s Tectonics festival. www.tectonicsfestival.com/glasgow