The methods of coupling the echo signals from a continuous-wave, frequency-modulated, echo-ranging sonar system to the human auditory system are discussed in relation to the acoustic cortical image that can be formed. The author points out that a considerable amount of blurring and distortion of the image can occur when the miniature earphones are operated remote from the meatus without a coupling tube. Because of the deleterious effect of this blurring and distortion on the perceived image, any conclusions drawn from a set of experiments involving such a coupling are questionable.
Continuous-wave frequency upconversion with a molecular optomechanical nanocavity
