How Speakers Create Overhead Sound from Ceiling Reflections

This patent describes a system using upward-firing speakers and special sound filters to trick your ears into hearing overhead sounds by reflecting audio off the ceiling.

What it covers

The patent describes an apparatus that uses an upward-firing speaker to bounce sound waves off a ceiling to a listener. A key component is a "virtual height filter" which applies a specific "frequency response curve" to the sound signal sent to this upward-firing speaker (Claim 1). This filter's job is to shape the reflected sound in a way that makes a listener perceive the sound as coming from above, creating a sense of "virtual height" (Claim 1). For example, it might use a "pinna filter response curve" that emphasizes certain frequencies (like a peak at 7 kHz and a dip at 12 kHz) to mimic how our ears naturally interpret overhead sounds (Claim 4). The system also includes a "crossover" that sends low-frequency sounds to a direct-firing speaker and high-frequency sounds to the upward-firing speaker (Claim 1).

What it doesn't cover

• —Does not cover speaker systems that create height effects solely from direct sound, without reflecting sound off a ceiling or upper surface.
• —Does not cover systems that do not apply a specific frequency response curve to the signal sent to the upward-firing driver.
• —Does not cover systems that lack a crossover to separate low frequencies for a direct-firing speaker and high frequencies for an upward-firing speaker.
• —Does not cover systems where the frequency response curve does not specifically aim to make the reflected sound seem like it's coming from overhead.
• —Does not cover systems that create height cues without compensating for direct sound cues in favor of reflected sound cues.

The clever bit

The clever part is precisely shaping the sound's frequency before it even leaves the upward-firing speaker, specifically to compensate for how our ears perceive sound reflected off a ceiling. This makes the reflected sound convincingly appear to come from above, rather than just sounding like it's coming from a speaker on the floor.

Why it matters

This technology is fundamental to how many home theater systems deliver immersive audio experiences, such as those found in Dolby Atmos setups. By using upward-firing speakers and sophisticated digital signal processing, it allows for a more compact and accessible way to achieve a three-dimensional sound field without requiring speakers to be mounted directly on the ceiling. This innovation helps bring cinematic sound quality into living rooms.

Real-world examples

• 1.Dolby Atmos enabled soundbars
• 2.Dolby Atmos enabled home theater speakers
• 3.Integrated TV speakers with upward-firing drivers