Mono sound uses a single channel of audio. In the world of multi-channel surround sound, it is hard to believe that mono was once the only sound format available. But mono still has its uses in hi-fi and home cinema...
MONO

Sound Formats

 

MONO

Mono sound is a single channel of audio. The first sound recordings were a mono signal and were played back through a single speaker, or through several speakers with each unit playing the same sound. Things have come a long way in the last 40 years as new sound formats using multiple audio channels and speakers have been developed for use in the cinema. Mono sound is still used as a component in some systems around today, although the use is generally due to limitations of the hardware (such as a television with a single speaker) rather than the original sound being recorded as a mono signal. The first LP's and cassettes were recorded in mono before the development of stereo recording technology. Sound in the cinema began by adding a single mono track to the filmstrip in the 1920's. The track was recorded into a strip on the film between the actual picture frame and the sprockets at the edge of the filmstrip. It was recorded as an optical signal. When the film was played through a projector, a beam of light passed through the optical track and created an image on a solar cell behind the filmstrip. This image was then converted to an electrical signal that corresponded to variations in the optical track and ultimately amplified into an audio signal.

 
   
Today, high quality hi-fi systems take advantage of the simplicity and cleanliness of the mono signal to create better sound. Using the principal that different electrical signals can interfere with each other when passing close to each other through electrical hardware, the different sound channels can be separated and amplified as individual mono components using a separate 'monobloc' amplifier stage.