Feature Story

Cisco's acoustic chamber lets you experience absolute silence

by Stephanie Chan

acoustic chamber cisco lab

How long can you last in a room of complete silence? We try to find out.

Upon entering Cisco's Acoustic Chamber deep within Building P of the company's San Jose headquarters, I was immediately hit with the sheer enormity of the room.

The Acoustic Chamber is just one section of Cisco's large array of environmental testing labs; where products are tested for regulatory compliance – including EMC, safety, NEBS (Network Equipment Building System), earthquake, and altitude. The Acoustic Lab was constructed for the purpose of testing the noise levels of routers and switches in various sizes.  

The wide space of the lab is capped off with extremely high ceilings—and every section of the room is covered with white sound-absorbing padding; acoustic foam. The visuals of the opaque-white, expansive room immediately transports visitors into a sci-fi fantasy.

My mission—along with discovering the purpose and history of one of Cisco's most exclusive testing labs—was to see how long I could withstand in a room of absolute silence. 

There had been rumors floating around I had been hearing from the employees in Building P—anecdotes like certain people being unable to stay in the lab for 30 seconds without washing over in nausea. Other stories included staying long enough in the chamber to hear the blood running through your veins.

These tales and more only fueled my desire to visit and experience the Acoustic Chamber—just me and my notebook.

The room itself is 49 feet long, 29 feet wide, and 35 feet high—plenty of room for chassis and the multitude of microphones, wires, and sound equipment needed to measure volume level of the chassis' whirring noises. The white padding in the room, which are constructed in symmetrical triangular shapes, are constructed of melamine foam.

Onder Cap, principal engineer from PDS Mechanical at Cisco and general tour guide and enthusiast of the Acoustic Chamber, tells me that the lab was completed in 2010 and has since created a stir about the exclusivity of the space.

"Cisco has impressive facilities when it comes to environmental testing," says Onder Cap, "I joke during the Acoustic Lab tour— the best acoustic lab west of the Mississippi."

The lab is accredited for formal NEBS testing, and formal acoustic testing is always witnessed by a third party independent agency, Intertek. Reports are then delivered and accepted by customers like Verizon, AT&T, and more.

NEBS compliant products need to be below the acoustic noise levels in sound power of 78 decibels, in room temperature less than 27 Celcius—and the meaning behind this is crucial.

Employees may be working 8-hour shifts in facilities with these products—and if a product's noise levels are kept below 78 decibels then these employees will not suffer hearing loss.

Because of this, the Acoustic Chamber is both an accomplishment in Cisco's dedication to the best quality assurance as well as a sight to behold. 

Before I knew it, it was time to spend some solo time in the chamber. The room, once closed, seems to lack any visible doors or exits. The team in Building P lead me into the spacious lab, and I took a seat on the ground in the middle of the room.

The first thing that surprises most people once they enter an entirely silent space is the sheer loudness of the quiet. Seemingly quite an anomaly, our ears are so used to constant noise of the everyday that absolute silence is jarring and can create a strange sense of loudness.

After what seemed like at least 15 to 20 minutes of soaking in the quiet and scribbling notes, I was ready to exit the chamber. While I wasn't sure I could hear blood running though my veins or my digestion system doing its work, I certainly noticed a persistent beat—the sound of my heartbeat in my head.

When exiting the lab, Cap and engineer Jeremy Wang smiled and told me I lasted just under five minutes.

While the mission of withstanding silence was over, I was still intrigued by the logistics and unique qualities of the lab itself. State of the art lab testing like Cisco's in-house facilities truly guarantees that products and procedures go through the most rigorous testing before going out into market.

And if you don't believe me—spend a few moments in absolute silence in the Acoustic Chamber and see for yourself.