Chabot's Baseball Stadium's score board

Noise Study Reveals Mixed Results for College Baseball Stadium

While sound-absorbing panels installed in Chabot’s batting cage have lowered average noise levels, instantaneous readings still surpass city code.

The Chabot College Baseball Stadium’s recent noise mitigation efforts have yielded mixed results, according to a presentation given to the Board of Trustees meeting on Sept. 10. Vice Chancellor Owen Letcher and consultant David Brinkerhoff from Forensic Analytic Consultants shared noise study findings from before and after installing sound-absorbing panels on the stadium’s batting cages.

The study, prompted by concerns of residents residents, evaluated noise levels at the fence line between the batting cages and nearby homes.s. Brinkerhoff explained that Hayward’s municipal code limits noise to 70 decibels during the day and 60 at night for commercial and industrial properties.

Baseball players practicing batting in batting cage
Photo by Samantha Valencia

The initial assessment recorded an average of 60.1 decibels over a 24-hour period at the fence line before the sound-deadening materials were installed. A follow-up study after the installation showed a reduction to 53.4 decibels.

Brinkerhoff emphasized the complexity of noise measurement, noting that the decibel scale is logarithmic rather than linear. “If I have an increase of three decibels, that converts to a sound pressure increase of twice as much sound pressure,” he explained.

The study used different measurement methods, including the community noise equivalent level (CNEL), which puts more emphasis on nighttime noise more. Using this metric, the pre-mitigation level was 61.2 decibels, dropping to 56.7 decibels after the sound-absorbing panels were installed.

“When we look at sort of our instantaneous readings, they exceed the code, the 60 or 70, all the time,” Brinkerhoff said. “During the daytime, during the nighttime, whether they’re in the batting cage or whether they’re not.”

Chabot baseball player practicing batting in front of sound absorbing panels
Photo by Samantha Valencia

The consultant argued that some form of averaging is necessary to interpret the data meaningfully, as common environmental noises often exceed the city’s limits. For example, Brinkerhoff noted that the board chair’s gavel measured 77 decibels during the meeting.

When averaged over 30-minute periods, the noise levels consistently fell below the city’s thresholds, both before and after the sound mitigation efforts. “The code doesn’t tell us how to do that averaging,” Brinkerhoff acknolwedged. “We need to use a little bit of common sense.”

Vice Chancellor Letcher explained that most of the baseball field components remained in their original locations after a 2020 construction project. The primary change was the installation of sound-absorbing panels on the batting cages, extending from ground level to 16 feet high.

As the college continues to balance its athletic program needs with community concerns, the noise study results present a nuanced picture. Although average noise levels have decreased, persistent high readings suggest that further discussion and more mitigation efforts may be needed to address neighborhood concerns.

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