The sound was one of relief, a release of tension and angst that might even have been cathartic. When Andrew Little, a 20-year-old substitute, slid the ball over the goalline in the 90th minute, he rescued Rangers from the kind of regret that would have felt distressing, and prompted a visceral response from the home crowd.
Rangers are now 10 points ahead of Celtic at the top of the Premier League, but they had to be jolted into life here. Having lacked the wherewithal to penetrate Hearts, they found themselves a goal down after 75 minutes when Scott Robinson was first to react after Allan McGregor had parried away Lee Wallace's shot.
"A couple of lapses of concentration set us back," said the Rangers manager, Walter Smith. "We had to show good spirit to get back into the game."
Until the opening goal, the game had been cloaked in restraint. Even the sense of insurrection among the supporters was muted. A protest comprising 12 banners, complaining against the influence of Lloyds, Rangers' bankers, on the club's finances, had been expected, but only three slogans were on show, mostly lost amid the Ibrox crowd.
There was a stuffiness to Hearts, although they might have seen some early enterprise rewarded had Christian Nade not snatched at a shot from 18 yards, sending the ball over the bar. The effort was memorable for its rarity, as the visitors were mostly intent on subduing the home side.
Rangers were earnest without being adroit enough to diminish their opponents' resolve. Steven Davis almost altered the shape of the game with a free-kick from 20 yards that was artfully placed towards the bottom corner, only for Marian Kello to turn the ball wide.
Rangers continued to struggle in the second half. When Nade was sent off for receiving a second yellow card in four minutes, for kicking the ball away, it was the home side who were reduced to disarray, and Hearts who took the initiative to score.
So at the final whistle it was Csaba Laszlo, the Hearts manager, who was left to rue what might have been.