Audio- means related to hearing. Audio communication is communication by voice. Telephone talk is the best example of audio communication. Listening to Radio programmes is also receiving audio communication.
Visual-means related to seeing something. Visual communication is communicating by picture, drawing, writing etc.
When we talk face-to-face it is mostly audio-visual communication. This is because,while hearing the voice we also see the person, moving lips, gesticulations etc.
Television newscast with photos and drawings and live interview is the best common example of audio-visual communication. Similarly movies and other projecting communication with commentary are audio-visual communication.
We receive a communication through one or more of our sense organs. The communication comprehension and retention will be fast and stable when the communication is originated and received by more than one sense organs. In telephone conversation, the emotional status of the person who talks has to be assessed by the variation in the voice. But when see face to face while talking, we can see the difference in the body language, lips, colour change of face or shivering etc. Similarly a mention of a serous incident in radio will not impact he listener as the news clip of the incident shown in TV.
In the same line if a communication uses in addition other senses like touch, smell, taste etc it will be still more effective. Just try by whistling to call some one, whistling and gesticulating, and whistling, gesticulating and nudging all at same time. You will now the inkstand difference.(Please try only on very close people who will not misunderstand you)
The recent developments of 3D and 4D theatres which use the movement(touch) and the smell by spreading odour are more effective and enjoyable.
An audo-visual communication be made effective by using all the pleasing features in the audio and visual side. Good songs, melodic tunes,baritone voices, nature' sounds etc as suitable to the situation. Visuals can be made effective when they are not blurred, when the do not strain the eyes, when they are moving at a pace which the eye and mind can follow easily and retain. Not to say that the medium of language of verbal communication used should be easy to follow for all.
To make an effective communication the first step is to place ourselves as the recipient and think back to see what we got and what we did not understand in some similar situations. We would have yearned for something more then. hat 'something more' is what is to be added for effective communication.