The measurements made last night will provide a baseline for measurements I’ll make outside the Coliseum, China Basin, and other ballparks. The decibel (dB) scale is logarithmic like the Richter scale, so 70 dB can be interpreted as twice as loud as 60 dB. (There’s a good primer on sound and noise propagation at quietsolution.com.) Last night I measured crowd noise in the bowl at three different points: Section 137 of the LF bleachers, the concourse behind Section 107, and the 4th row of Section 203. I don’t have a very sophisticated sound level meter that has real time logging or analysis capabilities, so take these measurements with a decent margin of error (± 3 dB) and several grains of salt. I used “A-weighting” for the measurements.
The ambient crowd noise in the seating bowl was in the 70-75 dB range when the crowd was idle. Drums and chants brought the noise up 5-8 dB. Between innings, the PA caused the range to be 75-82 dB. Compare that to the interior of a BART train (60 dB stopped/71 dB moving).

Readings from the bleachers (first three innings):

• Giambi intro/BALCO chant: 92 dB
• Giambi groundout to 1B: 99 dB
• Matsui HR to RF: 96 dB spike, 92 dB roar
• “Let Go ___” chant: 90 dB
• First 2-2 pitch to Sheffield: 90 dB
• Sheffield HR: 95 dB

Concourse behind 107, where a group of shrill young girls (A’s fans) were chanting back-and-forth with another group of slightly less shrill young boys (Yankees fans).

• Jeter drop/error: 101 dB
• Bradley single, 2 RBI: 104 dB
• Payton single: 104 dB
• “Let’s Go Oakland” chant: 96 dB
• Kendall beats out DP: 102 dB
• Bradley walks, scoring Ellis: 107 dB
• “Yankees Suck” chant: 95 dB
• Waiting in line for dollar dogs: 82-84 dB

Section 203. After the Scutaro single, many Yankees fans departed. The Thomas double begat a mass exodus. The readings:

• Damon grounds out to Duke: 92 dB
• “Take me out to the ballgame”: 82 dB throughout, 88 dB climax
• A-Rod K’s: 94 dB
• Giambi intro: 83 dB
• Giambi flies out: 93 dB
• Sharks highlight on DiamondVision: 91 dB
• Bradley triple: 99 dB
• Cano error, Payton safe: 104 dB
• Kendall single: 98 dB
• Scutaro RBI single: 101 dB
• Thomas double, 2 RBI: 101 dB

Other readings taken elsewhere in the stadium:

• Concourse behind the bleachers: 82 dB
• Section 103 aisle during Dot Racing climax: 95 dB (proving that Dot Racing isn’t the most cheered event at A’s games)
• BART bridge almost underneath southbound tracks before the game: 88 dB
• BART bridge before game, middle: 75 dB
• Standing platform in RF near flags, end of game: 89 dB
• BART bridge after game near saxophone player but not while he’s playing: 67 dB
• When the sax guy is playing (I really should ask him to play “Take the A Train” more often): 77 dB

It’s important to note that very few of these “events” lasted for more than 2-3 seconds. There was a slight trickle of people leaving as early as 9:00 p.m. Roughly half the crowd was left at the end.

I’ll make the next measurements in the Giants-Astros series next week, on the promenade outside the ballpark and McCovey Point (the little park across Mission Creek from the stadium). These will be important because unlike the current Coliseum, China Basin is an open design that doesn’t trap or absorb noise as well as the Coliseum.