Great feedback. It is proven (Adelson E. & Fraiberg, 1974) that sighted children need directed reaching (approaching, touching, feeling) to connect the visual system to movement. The same happens for echolocation, the user needs to "confirm" what he is hearing by touching it in order to establish a relationship between sound and space. Unfortunately, as you mention, many children are being limited by their parents in the process of developing this association, ultimately blocking the activation of the visual cortex and depraving the kid to develop spatial perception (which is fundamental to develop other skills). We have tried the device with kids, although it takes a time to train them, when they understand what they are feeling they start to run everywere to explore the sensation. The band has worked so far as a catalizer of exploration, but we are also in the process of developing scientific data with our current partnerships to prove that this device can accelerate the time it takes for a blind person to develop echolocation skills as well as to remove initial barriers in the process of learning the skill (fear).

Would it be possible to have headphones, bone conduction or otherwise, something they can still hear normal sounds through at least, which could convert an ultrasound "click" played by a speaker into a human audible "click" so they could use this in place of the audible clicking of human echolocation?

So a high frequency speaker on their head plays the sound, and the headphones convert the returning reflected sound in the correct frequency range into a lower frequency and the brain does the rest. Seem like if we can have active noise cancelling headphones removing sound frequencies, we can have a headphone with microphones converting a frequency.

Brilliant idea. Daniel Kish has a patent on a similar device that clicks at an audible frequency, you can adjust the clicking rate, power and pitch (different pitch provides different information).