By Stephen Eisenhammer

RIO DE JANEIRO (Reuters) - The Brazilian crowd was one of the quietest ever for their national soccer team, but it was still not quiet enough when the ball came into the box in the 29th minute.

With Brazil trailing Morocco 1-0 on Friday, the noise rose effortlessly from a nervous crowd used to cheering on their own, and striker Nonato, unable to hear the jingling bell inside the ball, missed.

"Silence please," the referee called to the stands once more. Brazil's coach shook his head in despair.

Blind five-a-side soccer, where players follow the ball by the rattling it makes as it rolls, may be the only sport at the Olympic and Paralympic Games in Rio de Janeiro where the raucous home crowd is a liability rather than a boon.

From judo to tennis and golf, Brazil's fans ripped up traditional crowd etiquette and brought a loud soccer culture to Olympic sport. Opposition athletes were often booed and chants from an army of yellow shirts deafened venues.

But this arena is different, as green signs asking for quiet attest. The players are totally or almost totally blind and wear eye masks to make sure no one has an advantage.

As the crowd wrestled with how to show their support, the "shhhhs" of fans demanding quiet were often louder than the cheers they were hoping to stop.

"It's so difficult. We're trying but we really want to shout," said Sonia Lima, 54, at half time when the noise level rose with collective relief that silence was, for a few minutes at least, not necessary.

Watching with four friends all dressed in Brazil shirts and waving flags, Lima said the silence felt unnatural. "When they get near the goal I just want to scream: 'Take a shot dammit.'"

Fortunately for the excitable crowd, Brazil overcame the noise to find their rhythm in the second half and clawed their way to a 3-1 win with stunning strikes from Ricardinho and Jefinho.

After the match, a relieved Jefinho tried not to discourage the crowd as he asked them to quiet down.

"That energy (of the crowd) is very important for us on the pitch. Silence is needed, but the support that comes from them is really important for us too," Jefinho, who is widely considered the greatest player to grace blind five-a-side soccer, told reporters.

The defending Paralympic champions hope the crowd learns the right way to show their support before Brazil play Turkey on Sunday.

"Over time the crowd will get used to our game and will start being quieter," Jefinho said.

(Reporting by Stephen Eisenhammer; Editing by Cynthia Osterman)