Research -- are there really Situations of Uncertainty and Situations of Confidence?
In 2006, Dr. Rob Wall Emerson from Western Michigan University and I asked 22 blind people with normal hearing to sit in my mother's lawnchairs at 3 different sites, and raise their hand when they heard something that they thought might be a vehicle approaching them.
We studied primarily 4 things:
The sites we chose to study (pictured below) were all two-lane, quiet intersections with a speed limit of 25 mph (I'll explain later what I mean by "quiet intersections").
- Detection-to-arrive time -- how many seconds passed from when one of the subjects first heard a vehicle until the vehicle arrived?
- Level of ambient sound -- when the subjects heard the vehicle, was there any masking noise and if so, how loud was it?
- Speed of vehicles -- how fast was the vehicle coming?
- Sound level of vehicles -- how loud was the vehicle when it passed?
Site 1 was a street that is straight and clear of obstructions for at least a block in each direction, so the vehicles approached in what we called the "straight" approaches.
On half the trials at this site, we put up a barrier to block the sound (the "baffle" approach).
Site 2 was the same crossing that Linda Sussman showed me and that you saw in the video on page 7.
The street has a severe bend to the right (the "severe bend" approach)
and a minor bend to the left (the "minor bend" approach).
Site 3 had a steep hill to the right (the "hill" approach)
and trees to the left (the "trees" approach).