The whine of the Subaru WRX-STI is faint in the distance, but the sound grows more audible as the car approaches, churns gravel in a tight turn, thens speed away.
The occasion was a routine driving course at DirtFish Rally School, but on this sunny Thursday morning, more ears than usual were listening in.
A few hundred yards distant, consultants Matt Roe and Alan Burt of Seattle-based SSA Acoustics had planted a sophisticated microphone for a sonic study of DirtFish Rally School’s aural effect on the neighborhood.
From their vantage point, the intermittent passage of gravel trucks drowned out most of the sounds around them. But the purpose of the equipment was to gauge noise from the cars running on the skid pad.
This busy spot was only one of three listening posts on the property line of the Old Mill Adventure Park, home to DirtFish. SSA placed four remote monitoring stations at homes surrounding the site.
Starting Thursday, Aug. 4, the monitoring ran through Sunday, Aug. 7, covering three full days of activity at DirtFish.
Devices recorded the average sound level and sound spikes, logging them as a percentage of the overall picture. Based on what the technicians were picking up Thursday morning, levels appeared to below any legal sonic threshold.
Still, “Irritation is all relative,” Burt said. “If your noise floor here is 15 (decibels), if you’re 10 decibels above that, that’s usually the level where people get annoyed or disturbed. It gets to be pretty subjective.”
Noise from DirtFish has come up this summer as the city of Snoqualmie considers annexation of the property. Meadowbrook resident Barbara Beatty, who spoke at a pre-annex hearing on August 8, likens the rally school’s noise to the sound of a neighbor constantly mowing.
From a different vantage point, looking down on the skid pad from the mill’s former helipad, DirtFish President Ross Bentley pointed out the cars going through maneuvers. At one point, a water tanker trundled out to lay down the dust with spray.
Bentley said the school is making no changes to its typical operation during the study.
A full class of eight people were set to drive four rally cars over the next three days.
“This is what we do,” Bentley said. “These are paying customers. We can’t mess around with customers.”
Bentley said DirtFish’s Subarus are modified to be quiet.
“We don’t want noisier,” Bentley said—that makes it harder to teach classes.
Snoqualmie Planning Director Nancy Tucker said study will give additional information to the council. Results are expected this week.
