It was the normality of the sound which was startling: a child's voice carried in the wind. One of the opposition fighters raised his hand and the others stopped, seemingly oblivious to the shelling or the rasping rattle of the regime's helicopter gunship overhead. Then a figure appeared around the corner, stepping through the rubble and guiding us to the house.
There are very few civilians to be seen in Salheddine, whose deserted streets are filled with fallen masonry, shattered glass and twisted metal. The dead are much more in evidence, bodies lying in the open, the rising stench from the ones buried in debris.
Despite launching a mission to reclaim Aleppo eight days ago, regime troops have so far failed to break through the opposition lines in the suburb of Salheddine or at the city's Iron Gate. There has, however, been a gathering of President Bashar al-Assad's forces, and threats from Damascus that a furious assault is impending. A senior regime official was reported as saying: "What you are seeing is the appetiser: the main course is yet to come."
Britain's Foreign Secretary, William Hague, warned yesterday of "more fighting, more bloodshed", and urged a renewed diplomatic push to force Assad to stop waging war on his own people. But with Kofi Annan's UN and Arab League-backed peace plan in tatters and Damascus largely back in regime hands, the rebels are determined to hold out in Aleppo, a key battleground which could determine the outcome of the 17-month conflict.
As the fight for Syria's largest city intensifies, there has been an exodus of the residents of Salheddine. But behind the blue tin door, living through the days and nights of bombardment, was Abu Omar's family of 10; on the second floor there was another family, of eight. They stood in huddles, the young and the elderly in the darkened hallway and stairs; frightened, hungry and bewildered, living off stale food and meagre water; making as little noise as possible so as not to attract attention.
"Now we must get them out of here," said Abdul-Karim Haddad, one of the rebel fighters who stumbled across the civilians. But cousins Abu Omar and Abu Mustapha, both unemployed labourers with 11 children between them, did not want to move their families.
"We don't have anywhere to go, not here, not in the villages, and if we leave we may lose our home," said Abu Omar, whose seven-year-old son is suffering from severe diarrhoea.
What they wanted was food and water and medicine for their children. After a little argument, Abu Mustapha agreed that his 72-year-old father could be escorted out. But the old man would not budge: "I was born in this house, they can bury me in front of it."
Abu Mustapha's oldest child, 17-year-old Abdullah, is now the sole breadwinner, working as a jobbing labourer and bringing in the meagre rations the family depend on. But they have not seen him for three days. Two other civilians – Khalid Mohammed Ali and Abdullah Izzedine Mohammed – had arrived an hour earlier on their daily inspection of their homes. Mr Ali's building was still standing but Mr Mohammed's had been demolished overnight.
"Look at that," he shouted. "Twenty years, 20 years we have lived there. Now what will we do? They have done this deliberately, they are criminals."
On this occasion, it was almost certainly a shell which had landed short of its mark. A large depot of the city's post office in the street behind had been burning for many hours. The regime forces may have thought the rebels were storing supplies there. Three members of the Bakri family came to Salheddine yesterday afternoon, checking on their home and carrying away as much as possible before the place, they believe, will be destroyed.
The youngest of them, Burhan al-Halali, is going to join the Free Syrian Army in the next few days. "I shall ask to come back to Salheddine so at least if I die I shall die defending my home," he said. "But I do not think that the regime will be able to defeat us here. We believe in what we are fighting for, they are just being paid by Assad."
Ahmed Yusuf Darish, meanwhile, was placing a third padlock on his front door to try to deter armed looters from taking advantage of the chaos. His family were worried about him returning to Salheddine, not just because of the shelling, but because he was a Christian.
"My brothers are worried because there are some people with the rebels who do not like Christians," he said. By "some people" Mr Darish meant Islamist groups who are present among the revolutionaries, although not in particularly large numbers.
Most of the men are friendly, but a few are taciturn and suspicious. "One of them with a big beard found out from a neighbour that I was a Christian. He just said 'I wish you were a Muslim'," said Mr Darish.
There has been little obvious sign of sectarian violence in Aleppo, unlike in some other parts of the country. The opposition forces have been accused of killing loyalists, while members of the Shabiha, the regime-backed paramilitary, and the secret police known as the Mukhabarat have also been subject to summary judgment. The overwhelming majority of those killed, however, have been Sunnis, who comprise the vast majority of the opposition, rather than Alawites, from which the ruling minority is drawn, or Christians.
But it is difficult to ascertain who is carrying out which killing. Four dead bodies lie in a park, victims, it was claimed, of mortar rounds. But, on closer inspection two of the corpses were blindfolded.
So why did Mr Darish keep coming back to Salheddine despite the risks? "We are Arabs and to us our homes are precious, even if we are poor. That is why people are going back to Homs, to Dera," he said. "But it is true there is no point in getting yourself killed over this, then there'll be no one to look after the family."
Waiting among patients at a mosque which acted as a first-aid centre was Khalid Mohammed Ali, his left arm in a bandage. The wound from a piece of flying shrapnel was not serious, he was lucky. But surely this would stop him continuing to check his home? No, he shook his head, he will be back. "Allah will decide what happens."
There has been little obvious sectarian violence in Aleppo, unlike in other parts of the country