HOUSTON --After one of Houston's last playoff games, the opposing team told Texans' brass, they'd never played in a louder stadium.
Don't expect Saturday to be any different.
"NRG (stadium) was architecturally designed to be one of the loudest stadiums in the NFL and they accomplished that," said Rob McKinney, who worked on the stadium's sound design for the Houston Livestock Show & Rodeo.
McKinney's Houston-based company, LD Systems, also installed the sound system used on game days. At the time, it was the largest set of speakers anywhere. McKinney said even that is not enough power to be heard over the roar of an NRG crowd.
According to McKinney -- a Rice University educated Electrical Engineer -- everything about the design of the stadium contributes to the noise: The sound bounces off seats, the fast rise of the concourses, the vertical services close to the field -- and the roof. McKinney calls that 'arrrr' noise, "reflected energy."
He likens that tight fabric on the retractable roof to the head of a drum being struck by the screams of 70,000 fans all at once.
"It's a real stretched tensile structure so it's highly reflective there's a bunch of steel up there it contributes to making it a real loud stadium - a highly reflective stadium," he said.
The noise could be one reason the Texans haven't opened their roof all season.
Texans' president Jamey Rootes admits "There could be a little difference when you close the roof."
McKinney says he hasn't studied but if he had to, he could prove it. On Saturday he predicts "it will be deafeningly loud."
There are ways to combat the sound. When NRG Stadium transforms into the home of the Rodeo, organizers hang 35,000 pounds of fabric from the rafters to keep the sound from bouncing around.
That, combined with an added state of the art speaker system, makes it sound far better for a concert. The fabric isn't there on game days. It's likely not an oversight -- but the Texans don't like to talk about sound levels too much.
Last year, the Atlanta Falcons got in trouble with the league for piping crowd noise through their stadium sound system to distract opposing teams. The Texans say it doesn't happen here.
McKinney tells us it would be real easy to detect. The hundreds of speakers at NRG are pointed directly at fans and they would hear it. he explained. He added the team on the field likely hears little of the noise from the loudspeakers due to where the finely tuned system aims the energy.
The Texans say the weekly roof decision is about fan comfort, but even that contributes to noise levels. Uncomfortable fans, either too hot or too cold, wander the concourse looking for relief, McKinney said. Fans who are comfortably climate controlled stay and yell.
And all their screams bounce right off that roof.