Acoustic analysis of the Sonic Guide

Abstract

The Sonic Guide is an eyeglass configured sonar-type device available for the orientation and mobility of blind individuals. It operates by emitting toward and receiving from target objects modulated stimuli whose intensity and frequency components directly result from the distance and physical properties of the target. This investigation measured the sound pressure level output, via a sound level meter, of four Sonic Guide temples, at three volume control settings, for six octave frequencies (250–8000 Hz), at six distances (35.6 cm–4.6 m) for a total of 432 measurements. Means, standard deviations, and an ANOVA were computed to investigate the consistency of output across temples and the interactions among frequencies with volume control setting and with distance. Across temples, the Sonic Guide devices were found consistent at each volume control setting, at each frequency, and for each distance measured. Higher volume control settings produced proportionally greater output in the higher frequencies than in the lower frequencies. As distance increased, the peak of the response shifted upward in frequency, although overall, targets at shorter distances produced greater intensity at lower frequencies than did the more distant targets at higher frequencies. Implications for use of the Sonic Guide by hearing-impaired individuals are discussed.