An Appeals Court judge in my home state ruled this month that police officers cannot give out speeding tickets based solely on the sound of a passing vehicle, unless they have some kind of specialist’s credentials as listeners. The ruling overturned two previous decisions against Daniel Freitag, who got a ticket in 2007 while driving on business in his Navigator SUV. The full ruling is here.

The officer in the case, Ken Roth, was unable to make a reliable radar reading, but he claimed that he could tell simply by listening that Freitag’s vehicle was speeding.

According to the decision:

Ptl. Roth testified at trial that he was parked in his patrol car along the side of U.S. 42 at 9:16 p.m. on October 8, 2007, when he heard a vehicle he could not yet see. He testified that, based on the sound of the vehicle, he believed it was traveling in excess of the 35 m.p.h. posted speed limit. The officer testified that he “audibly heard the speeding, not the speed of the vehicle.” Ptl. Roth clarified: “As it approached I could hear the vehicle on the roadway which based on my training and experience it is consistent with a vehicle that was in excess of the posted speed limit.”

Fascinatingly, Roth distinguishes between the sound of speeding and the sound of moving at any specific speed. The sound of speeding is marked, presumably, by aggressive engine noise. We’ve all heard vehicles that sound like this. Often enough, it’s a jock move.

But, by hearing alone, what would distinguish a normal engine working hard enough to speed from an inefficient engine working just hard enough to drive the limit? Or an engine in a car with a broken muffler?

Nothing could distinguish them. Or, rather, doing so would require an ear trained to identify engine types, and to be able to hear precisely how these engines were operating. The officer’s claim, that he’d heard lots of speeding cars before, did not convince the judge that he was qualified to make such an assessment.

From her opinion:

It is simply incredible, in the absence of reliable scientific, technical, or other specialized information, to believe that one could hear an unidentified vehicle “speeding” without being able to determine the actual speed of the vehicle. The officer offered no testimony regarding how he might have been trained to audibly distinguish various speeds, let alone to distinguish the speeds of various makes and models of vehicles.

What’s intriguing about this ruling is that, thinking beyond conventional empirical evidence (namely, the radar gun), the judge alludes to the possibility of a hypothetical listener skilled enough to be able to do exactly what Officer Roth only imagined he could – to listen as well as the radar sees. This would, admittedly, be a type of listening disciplined by visualism inasmuch as it would be burdened with the task of identification, which is a visual metaphor. But it would still be an impressive technique.

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