Audio elements of a video are of equal importance to story and image elements.
Voice-over
A voice-over is a narration or commentary that accompanies the visual elements in the video. It is called a voice-over because it is a sound commentary that is produced off screen. Voice-over is a popular convention in videos because it is an effective way to communicate verbal information in the absence of dialogue.
Dialogue
The speech of the people in the video is the most important element of the overall soundtrack. It is important to ensure that the audience can identify the person talking within any part of a sequence.
Ambient sound
Ambient sound – the sound that is naturally present within the scene – is often used in videos. Sounds within experiments, procedures or the environment may be a vital part of the production. Therefore, a good microphone should be used while recording.
In some interviews, it might be more effective to use the tone of the room, based on the reverberation of the location. Ambient sound provides a realistic background for visual elements that other audio effects cannot provide. Ambient sound can be used continuously, but is generally used in conjunction with other audio elements.
Music
Music can be used as a continuous background soundtrack. Alternatively, it can be introduced into sequences to heighten emotional awareness; create pauses; identify characters; and help make transitions from sequences, scenes or shots.
Sound effects
A sound effect is any sound that is not speech, music or ambience and is artificially injected into the soundtrack to enhance it. Many sound-effect libraries can be accessed online that have used excellent recording and postproduction tools to produce high-quality sounds. Alternatively, it might be worth creating your own sound effects for a specific scene.
Silence
Silence is a very effective audio element in videos. It might be used to focus the viewer’s attention on the visual elements on screen, or create tension within the dialogue of 2 people. The quality of the silence matters; it needs to add to the overall effect within the sequence.