Audio Video Recording And Editing 4(1+3)

Lesson 03: Understanding The Components Of Sound

Rhythm

Rhythm is a recurring sound that alternates between strong and weak elements. Small blocks of wood when rapped with measured regularity may sound like a marching troop. Similarly, two coconut shells struck on a stone in a rhythmic fashion recreates the sound of a horse galloping. Done with precision, the effect would be authentic. What's more it could provide the background for a peppy song!

Sound envelope components include attack, sustain, and decay. Under­standing these concepts will help us design sound to suit a video.
Sound takes some time to reach its peak, remains so at a particular level for a short duration, and then falls acutely. The graph in Fig. 7.2 shows the typical journey of sound beginning at level A and taking some time to reach level B. This duration between A and B can be termed attack. Having reached B, it holds itself until C. This duration between Band C can be termed sustain. The sound then declines fast from C to D. The du­ration between C and D can be termed decay.

A thud on a table, a gunshot, etc. are ex­amples of fast attack. However, when you tear a piece of cloth, the attack is slow; the sound sustains for some time and decays fast. The en­ergy from the source determines how long a sound can sustain. When the energy levels begin to fall, the sound begins to decay. Suppose you have the sound of an ambulance for just 3 seconds but need it for 4½seconds. You can manipulate the duration by copy­ing the sustain part for the required time and increasing the duration to 4 ½ min­utes. You will know how to do this when you sit on the non-linear edit suite.

By increasing or decreasing the playback speed you can change the prop­erties of a sound effect. You would have noticed that on some comedy shows when two persons begin '&> argue, the speech is normal. When it goes on for a long time, the speech is contorted, lending the scene a comic effect. In this case, the speed of normal speech has been increased by at least three to four times.

Try it out when you get an opportunity to work on the non-linear edit suite. Using the components explained above, multiple permutations and combinations of sound can be created.