If echoes do come back, then the closer the obstruction the faster the succession of bleeps and the deeper the pitch of each bleep, Without needing a constant companion to guide him.

• 假如真有回波到来，则障碍物越近连续的信号声越快，强度也越高。通过实践盲人可以借助超声电筒的帮助过一种比较正常的生活枣无需一个固定伙伴来引导他。