Have you ever heard an accessible pedestrian signal at a cross walk that sounds like a chirp, intended to help people with visual impairments safely cross streets? Many
of these signals have been replaced because they were not optimally effective and
can be difficult to interpret. New recommendations include a rapid ticking or
beeping sound and/or a speech message saying the walk sign is on to help people
cross streets more safely. What aspects of complex sounds-spatial location or
timbre, loudness or pitch perception-could be used to improve these systems even
more and why?