Calibrating signal level of electronically controlled acoustic signal source for guidance system assisting blind in crossing road by detecting ambient noise level and acoustic signal from signal source at point on crossing

摘要

The method involves using a remote control device (28) which separately detects the ambient noise level and the acoustic signal from the signal source at least one point on the crossing. The ratio of the signals is determined and compared with a reference ratio. A loudness setting signal is derived from the difference between the ratios, and is transmitted to the guidance system. An Independent claim is included for a guidance system.