Why exactly is CenturyLink Field so loud?


Average ambient street noise on San Francisco's Embarcadero is about 68 to 70 decibels. In Seattle Sunday, the Niners may be exposed to 135 to 140 decibels. And, there might be something hinky going on, too.

Imagine 60,000 mutually screeching fans and you'll get a sense of what the 49ers face in Seattle's CenturyLink Field on Sunday. Hence, the loud speakers at recent 49ers practices and the earplugs worn by opposing players in Seattle's stadium because to hear the Seahawks tell it, they designed their place to be deafening and reflect sound.

It has clamshell roofs with parabolic shapes. It has cantilever construction that they say keeps the sound inside. And, it has 40 rows of aluminum bleachers. It's all designed for maximum volume.

A few weeks ago, fans in Seattle set an NFL sound record of almost 138 decibels on the peak scale, which would violate federal OSHA standards, we might add. That level of sound is deafening, literally.

So are they lying?

Charles Salter knows just a little about sound and architecture. He designs buildings and teaches acoustics at UC Berkeley. And while yes, he says a structure can focus sound, he says it can only focus so much.

And that leads to suspicions. "The optimum amplification for natural sound is maybe 3 to 5 decibels, and then you can start amplifying the signal to get it louder and louder using loudspeakers," he explained.

They don't do that. Do they?

"I don't know," Salter said.

Do you think they might?

"Possibly," Salter said.

Not that we're accusing Seattle of cheating. After all, those laws of physics were meant to be broken, right?

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