A project team may supply two acoustic figures and ask for a simple before-and-after graphic. The design temptation is to shrink a sound icon in direct proportion to the numbers. Before doing that, agree what the graphic is claiming. A numerical change in decibels is not automatically the same percentage change in sound energy, pressure or perceived loudness.
CCOHS explains the logarithmic nature of the decibel scale. A film commissioner does not need to calculate acoustic quantities to act on that distinction. The useful decision is to keep the supplied quantity as itself unless the specialist provides a valid, necessary interpretation.
Identify the message before selecting a metaphor
Does the audience need the actual figures, a specialist-approved description of the result or simply an explanation of the project objective? Those are different editorial tasks. A precise number may not be necessary if the film is only introducing the rationale for the work.
If the values are central, obtain their full labels and comparison basis. A plain pair of properly identified values can be clearer than a large animated dial. Do not replace unfamiliar technical language with a percentage merely because percentages seem easier to market.
Ask the specialist to approve any phrase such as half as loud or a stated reduction in energy. Those phrases refer to different things and should not be derived by the editor from a casual subtraction or ratio of decibel figures.
Give the chart an honest scale
A labelled decibel axis can be used when the comparison is appropriate. The axis should make its numerical scale clear, and the narration should not silently turn its bar lengths into a linear measure of perceived sound.
Avoid shrinking a speaker icon, crowd image or wave amplitude by a percentage unrelated to the supplied quantity. Such visual metaphors can make a stronger statement than the written label. The fact that the graphic includes the correct numbers does not cancel that implication.
If a qualitative illustration is preferred, make it visibly illustrative. It can establish the direction of an approved comparison without pretending to calculate the magnitude through icon size or colour saturation.
A hypothetical machinery-enclosure story
A contractor's film includes a specialist-approved acoustic comparison. The marketing draft converts the two decibel figures into a percentage by dividing one by the other and proposes an animation using that percentage.
The producer pauses the graphic brief and asks for an interpretation from the record's owner. The final treatment uses the correctly named figures and a bounded explanation, without inventing a new percentage claim.
The result may look less dramatic than the first storyboard, but it is more useful to a prospective buyer who wants to understand what was actually assessed. The contractor's contribution remains visible through the project story rather than exaggerated mathematics.
Review the visual and spoken claims together
Ask the reviewer to describe the meaning of the graphic without reading its small print. If their interpretation differs from the approved statement, change the visual rather than relying on a disclaimer to rescue it.
This check belongs before final animation and again after shorter versions are made. A cropped caption or removed axis can turn an initially careful graphic into a different claim. Keep the quantity, comparison and interpretation connected wherever the result appears.
Source and scope
CCOHS Noise: Basic Information supplies the narrow acoustic context. The filming recommendations and hypothetical example are original editorial guidance, not acoustic design or testing advice.
Discuss the project explanation with Live Images and agree the production scope and specialist review.
Prepared with AI assistance for Live Images. Planning guidance is general; suitability and production scope must be agreed for your project.