physics of Holoplot’s “Wave Field Synthesis” : how they can make a sound seem like it’s whispering in your ear?

To understand how Holoplot makes a sound “whisper in your ear” from 100 feet away, we have to stop thinking about loudspeakers and start thinking about holograms.

The physics relies on a concept called the Huygens-Fresnel Principle, which states that any large sound wave is actually made up of thousands of tiny, overlapping spherical waves.

Holoplot reverses this principle. Instead of one big speaker pushing air, they use thousands of tiny, individually controlled drivers to reconstruct sound waves shape-by-shape.

1. The Physics: Synthesizing the Wave

In a traditional setup, sound radiates from the speaker like ripples in a pond. If you are far away, the ripples are weak and wide.

In Wave Field Synthesis (WFS), the computer calculates exactly when each of the 7,000+ tiny speakers needs to fire to create a specific shape in the air.

• The Virtual Source: By firing the outer speakers slightly later than the center speakers, the system creates a curved (concave) wavefront.
• The Convergence: These waves don’t spread out; they converge (focus) toward a specific point in the air, similar to how a magnifying glass focuses light into a hot dot.

2. The “Whisper” Effect (Focused Source)

The “whisper in your ear” effect occurs when the system places that focal point inside the audience, right next to your head.

• Point of Origin: Your brain locates sound based on where the wave curvature originates. Because the sound waves physically converge at a point inches from your ear before expanding again, your brain perceives that point as the source of the sound.
• Private Audio: If the focal point is tight enough, the person sitting two seats away might hear nothing, or only a faint murmur, because the sound waves haven’t reached them or have already scattered.

3. Beamforming vs. WFS

It is important to distinguish between the two technologies mentioned in the announcement, as they do different jobs:

Technology	What it controls	The Physics
3D Beamforming	Volume & Coverage	“Steers” the sound energy like a laser beam to ensure the back row gets the same volume as the front row.
Wave Field Synthesis	Location & Space	“Sculpts” the wavefront to trick the brain into thinking sound is coming from a specific point in 3D space (e.g., a whisper in your ear).