By now in Donetsk, everyone from children to pensioners can differentiate between the sound of incoming and outgoing fire, or identify a mortar or Grad rocket from its pitch. At the Donbass Opera, however, people are given very different choices to stimulate the senses: Verdi or Puccini; Strauss or Bizet.

In a city where armed men in camouflage ride down the main street in tanks, more than half of the residents have fled and most shops and restaurants are closed, opera should perhaps be the last thing on anyone’s mind. But remarkably, and against all the odds, the city’s opera house has remained open, despite the fact that none of the troupe have been paid in months, all four conductors have left town and the singers take a risk every time they travel to work. It is a risk, however, that they say is worth it.

“Even if people don’t come, they know the theatre is open, and that in itself is a big boost: it makes things seem more normal,” said baritone Sergei Dubnitsky, who last Sunday sang the lead in Die Fledermaus, Johann Strauss’s hammy comedy of mistaken identities. In addition to taking on leading operatic parts, he has learned to conduct and picked up the baton to conduct La Traviata at the weekend.

“Whenever you perform, you can sense from the stage what kind of connection you are making with the audience, whether the audience is engaged. Of course there are productions that are better or worse than others, but overall it has become much easier to find those connections, people are much more engaged.”

Lidia Kachalova, former leading soloist at the Donetsk opera and ballet theatre

It may seem odd to hum along to operatic farce when just a few miles away there are frontlines, but the audience appears genuinely delighted as the singers prance around the stage during Die Fledermaus. The production radiates lightheartedness and innocence – qualities in short supply in today’s Donetsk.

“When you are surrounded by ugliness, beauty becomes something you cherish even more,” said Galina, a 42-year-old nurse, who had brought her two teenage children to the theatre to cheer them up.

When you are surrounded by ugliness, beauty becomes something you cherish even more Galina, 42, nurse and theatregoer

A striking, Stalinist neoclassic building on Donetsk’s main thoroughfare, the theatre was opened in April 1941, months before the Nazi occupation of Stalino, as the city was called. The 960-seat auditorium has a sense of grandeur; the ornate foyer features busts of Russian and Ukrainian literary greats Alexander Pushkin and Taras Shevchenko.

So far, none of the theatre employees has been among the more than 5,000 people who have died since the conflict between local separatists backed by Russia and Ukrainian forces loyal to Kiev began. But the troupe has not escaped unscathed. Last weekend a shell caused serious damage to the apartment of one of the leading soloists. In September, the theatre’s warehouse on the outskirts of town was hit by a shell. The stage decorations for a number of productions, including The Flying Dutchman, the theatre’s calling card, were destroyed.

Before the new season in October, Vasily Ryabenky, who had led the theatre for more than two decades, gathered the collective and asked whether they could carry on. Everyone said they should and they agreed to put on Die Fledermaus on 4 October.

“Tickets were free and there were hundreds of people queuing,” said the deputy director, Natalia Kovalyova. “People were upset they couldn’t get in. In the end we had people sitting on the steps, standing in the wings, we crammed in as many as we could. Two old ladies were in tears, on their knees and kissing his hands in gratitude that he had opened the season.”

Visitors take pictures with a statue of Alexander Pushkin during the intermission

Three days later, Ryabenky, 55, collapsed and died from a heart attack his colleagues are convinced came about through the stress of keeping the theatre open in such trying conditions. He was replaced by a local museum director, and the rest of the collective decided they had to go ahead with the season.

Due to the security situation, performances now only take place during daylight hours and only on weekends. Last weekend, the Saturday performance of La Bohème was cancelled due to a day of mourning for eight people killed when a trolleybus stop in Donetsk was attacked with mortars two days previously.

The Sunday performance of Die Fledermaus was also in danger of cancellation, after mortar damage to the local power station cut power to the opera house an hour before the 2pm start time. But at 2.29pm, amid the rumbling of artillery in the distance, the lights flickered back on and the 200 or so people waiting outside let out a cheer. The actors warmed up, got into their costumes and had their makeup put on in the space of 15 minutes, and the show began.

“There have been a couple of occasions when the shelling has got close to the centre and we’ve had to get everyone into the bomb shelter in the basement,” said Igor Ivanov, the deputy director of the theatre. “But it’s never happened in a performance – everyone is too busy listening to the music.”

Indeed, music is not just a balm for the soul, it is also a way of shutting out the endless sound of artillery.

Svetlana Taran-Maleeva, soloist, applies makeup next to a window. The electricity was cut before a performance of Die Fledermaus

“At home, the walls are always shaking,” said 80-year-old Lidia Kachalova, who has been at the theatre since 1958, first as a soloist and now as a stage manger. She lives near Donetsk’s railway station, an area that has seen heavy fighting in recent months, and refuses to leave the city even though most of her family have gone to western Ukraine.

“My life is here, my apartment is here, my husband’s grave is here. How I can I leave the place where my husband is buried? My son calls me and tells me to leave, to come and stay with him. But I’m not going to leave my own apartment. I just put on some good music, turn up the volume, and think good thoughts.”

Dubnitsky has thought about leaving many times. “Maybe it sounds pretentious, but I think we have a certain moral obligation to stay,” he said. “We have our performances, our audience, our city to think about. You can treat wounds with medicines, but art is medicine for the soul.”

Maybe it sounds pretentious, but I think we have a certain moral obligation to stay Sergei Dubnitsky, baritone

Anna Netrebko, the Russian soprano, caused a political storm when she donated 1m roubles (about £9,500) to the theatre in December, mainly because she handed it to one of the separatist political leaders, and then posed with a flag of Novorossia, the self-declared political entity encompassing much of eastern Ukraine.

Netrebko said she did not know what the flag was until it was too late, but that has not stopped her from garnering criticism, and she was accosted by a man waving a Ukrainian flag as she basked in applause at the curtain call at the Metropolitan Opera in New York on Friday.

But in Donetsk there is gratitude for the money, which was delivered to the theatre in a sack, in cash. Everyone from the general director to the cleaners were given 3,000 roubles as a one-off payment, said Kovalyova, and the remainder was used to pay for medicines.

Artists have received only one, reduced, salary payment in the past half a year, so the money was acutely needed. Others have offered donations, but the theatre is unable to accept them, as, like everyone else in Donetsk, they are unable to access its bank account. Many find themselves unable to pay for basic needs, but go on performing.

Inside the troupe, people try not to talk about politics, but it is clear that here too there are divisions. One of the leading sopranos travelled to Kiev to receive an award from President Petro Poroshenko in November, while another group of singers performed a hospital concert for wounded separatist fighters last Thursday, wishing them a speedy recovery and exhorting them to victory.

Viktoria Volchenko, soloist. In Donetsk, music is not just a balm for the soul, it is also a way of shutting out the endless sound of artillery

“I don’t know who is right and who is wrong, maybe only in heaven they know. All I know is that this shouldn’t happen,” said Kachalova, shaking her head. “Everyone supposedly has brains, everyone appears to be educated, and everyone is an adult. What is the problem, then? How can they let this happen?”

Her solution to the madness is musical: “You leave the house in the morning, and there’s ice on the ground, wind in your face, snow falling, and the sound of bombs exploding everywhere. What can be better than to walk along and sing Strauss to yourself?”