THX.com » Acoustics

THX Certified Cinema Reverberation Control

rhennigan — Sun, 20 Dec 2009 18:07:02 +0000

Reverberation is the presence of sound after its source has stopped – much like an echo. In a movie theater, reverberation often builds as sound reflects off surfaces such as walls, floors and ceilings.

For example, in an action film, such Iron Man, there are several instances where the movie’s hero (Tony Stark) is being chased through the sky by two fighter jets, followed immediately by quiet, more dialogue-driven moments. In a THX Certified Cinema with tightly controlled reverberation, the sound of jet engines and explosions ends immediately, never bleeding over into the next scene.

Among the methods THX uses to control reverberation is covering the rear wall of the auditorium with thick, absorptive material. This prevents the direct sound of the screen speakers from reflecting into the seating area. THX also requires the placement of absorptive materials on the sidewalls, down to the audience’s ear level. This reduces the amount of sidewall reflections.

With acoustic paneling

Acoustic paneling controls reverberation, or echo effect, in a THX Certified Cinema.

Without acoustic paneling

Sound bounces off the walls without acoustic paneling, interfering with the movie’s soundtrack.

Contact THX for additional information on the THX Certified Cinema program.

THX Auditorium Isolation

rhennigan — Sun, 20 Dec 2009 18:00:58 +0000

THX Certified Cinemas are quiet. They feature massive wall structures to isolate the cinema from the outside world—creating a pristine audio sanctuary. With these walls, audiences can focus on the movie experience in front of them, as opposed to distracting sounds from neighboring cinema auditoriums, outside traffic and lobby activity.

THX Sound Isolation Methods

Large quantity of building material
Isolating air gap
Large quantity of building material

With THX Sound Isolation

The walls in a THX Certified Cinema are constructed to provide sound isolation from other auditoriums.

Without THX Sound Isolation

Without the use of the recommended building materials, thin wall construction allows sound to pass through to neighboring auditoriums.

Contact THX for additional information on the THX Certified Cinema program.

Speaker Layout and Baffle Wall

rhennigan — Sun, 20 Dec 2009 17:54:16 +0000

Unique to every THX Certified Cinema is the THX “baffle wall.” If you were to peel away the screen at any THX Certified Cinema, you will see a massive wall of speakers housed in an acoustic baffle (speaker system enclosure).

The baffle wall is approximately the same size as the screen, providing a solid, smooth and uninterrupted surface to distribute sound throughout the auditorium. It produces a large sound image and accurately tracks sound elements with the onscreen action. This makes panning shots and off-screen sounds more believable and natural, helping to pull audiences into the storyline. Without a baffle wall, sound is uncontrolled – producing a weak, uneven image.

With the baffle wall

The baffle wall in a THX Certified Cinema controls the sound behind the screen – projecting a smooth audio experience out to the audience.

Without the baffle wall

Without the baffle wall, sound is uncontrolled behind the screen – producing a weak sound image that “jumps” across the screen.