Sound imaging is an audio jargon term used for the aspect of sound recording and reproduction concerning spatial locations of the sound source(s), both laterally and in depth. An image is 'good' if the performers can be effortlessly located; 'bad' if there is no hope of doing so. For many listeners, good imaging adds markedly to the pleasure of reproduced music. One may speculate that this is due to the evolutionaryimportance to humans of knowing where sounds are coming from, and that imaging may therefore be more important than some purely esthetic considerations in satisfying the listener. Listeners do exist who have difficulty paying attention to the musical content of a recording if the imaging is not good. Video from portable cameras is analysed to calculate the distance of obstacles and predict the movements of people and cars. This information is then transformed and relayed to a blind person as a three-dimensional ‘picture’ of sound. The concept is apparently simple and two prototypes have been successfully tested. Laser and digital video cameras become the eyes for the blind man and see the objects and activity going on around him. A blind person wears headphones and hears how sounds change as they move around. The stereo audio system makes it possible to place sounds so that the brain can interpret them as a point in space. Sounds get louder as you walk towards objects, quieter as you move away. Objects to your right are heard on your right, and if you move your head the sound moves too. And if something is heading right for you, you'll hear it coming, with a tone that tells you to get out of the way.The quality of the imaging arriving at the listener's ear depends on numerous factors, of which the most important is the original "miking", that is, the choice and arrangement of the recording microphones (where "choice" refers here not to the brands chosen, but to the size and shape of the microphone diaphragms, and "arrangement" refers to microphone placement and orientation relative to other microphones).