Description

Before we start talking about home theatre soundproofing, we need to clarify the terminology. A home theater is a dedicated space or setup in your home designed to recreate the cinematic experience. It combines high-quality video and audio equipment for immersive movie watching.

 

Such systems for residential premises typically include the following elements:

• televisions or projectors;
• video signal sources;
• AV receivers;
• Acoustics.

 

Soundproofing your home theater is essential for an immersive cinematic experience. It prevents external noise from disrupting your movie, allowing you to fully enjoy the audio. Additionally, it keeps loud sounds from disturbing others in your home or neighbors. Soundproofing also improves the sound quality within the theater by reducing echoes and reverberations, enhancing your overall audio experience

 

Let’s figure out how sound insulation differs from sound absorption. What is soundproofing? Is it sound insulation, or is it sound absorption, or, is it both?

Sound insulation

 

The complete elimination, or reduction to insignificant levels, of noise entering a room from the outside is known as sound insulation.

Sound absorption

– allows you to keep the soundtrack of what is happening in the room within its confines.

 

To solve both issues, special materials are used and a special room geometry is developed. The right combination of these two factors allows you to deal with several types of noise. Noise that enters the room from the outside or inadvertently escapes from it through unprotected walls.

Airborne sound

 

All sounds that are transmitted through the air – conversations, the noise of operating equipment, the barking of a dog, and even an attack by combat tripods from Mars are airborne sounds.

Impact noise

 

knocks that occur when objects fall on the floor, which is the ceiling of the home theatre room, or when they hit the walls, are impact noise. In the cinema itself, percussive sounds can be produced by subwoofers, and such noises are audible from outside even if the dialogues and music do not break through.

Structural noise

 

The noise that occurs during the operation of the building’s engineering systems: the hum of ventilation, the movement of the elevator along the shaft, are structural.

Acoustic noise

Acoustic noise is most often an echo, which makes it difficult to understand what is happening on the screen.

 

The most pressing noise problems for cinema audiences are the first two since they can equally be of external and internal origin.

Of course, any home theatre room uses special acoustic panels, mounted on the walls and capable of absorbing unwanted sounds. But you should not rely only on them. The area and design of even the most expensive and high-quality models are not enough to effectively solve the problem of home theatre soundproofing.

Acoustic kits for home theatre soundproofing?

Home theaters must have a powerful acoustic system. It is extremely important to achieve the effect of personal presence to ensure comfortable viewing of films or listening to favorite music. To do this, it is necessary to correctly arrange all the speakers in the room. The largest speakers should be used to sound the front channel, which is responsible for transmitting music and sound effects. Front speakers should be placed in the center line of the room, choosing the right direction so that the emitted sound streams are concentrated on the location of the audience.

Also, the acoustic system for a home theater provides for the installation of rear channel speakers that create surround sound. Such speakers often work with the Dolby Digital, DTS, and Dolby Surround standards. Such speakers are chosen to be the smallest in size, and long acoustic cables are used to connect to the AV receiver.

 

The speakers should be installed behind the viewers, above the hearing level. Thanks to this arrangement, the creation of non-directional sound is ensured, and you need to try to make the distribution of audio signals as diffuse as possible. To do this, it is advisable to direct the flow of sound waves to the walls or ceiling, since when reflected from surfaces, they will give the most natural echo effect.

Types of soundproofing materials

Reliable soundproofing of a cinema from professionals is ensured by using various materials:

• acoustic plates;
• sound-absorbing (noise-absorbing) panels;
• acoustic fabrics.

Acoustic slabs (panels) are considered universal, as they not only provide high-quality sound insulation but are also a modern finishing material. Acoustic panels come in two types: single- and double-layer. Single-layer ones are made of pressed artificial material; they are thin and affordable.

 

Sound-absorbing boards block airborne noise well; they significantly reduce the level of reverberation and vibration load from the surface of walls and floors. This material is made from glass, wood, basalt fiber, or flax. The effect of sound-absorbing plates is as follows: while the sound wave tries to pass through the smallest pores, it loses its strength.

Acoustic fabrics are used for draping frame structures. They are suitable for masking speakers located inside walls, making the acoustics in the cinema invisible to visitors.

New or old building? home theatre soundproofing

If you are just building a new house and plan to allocate a separate room for a home theater, soundproofing should be immediately included in the project.

Modern walls, unfortunately, have good sound conductivity. To determine the level of sound transmission of different materials, the sound insulation index, measured in decibels, is used. The higher the index value, the better the material blocks sound. Thus, plasterboard walls have a sound insulation index of 40 decibels. This means that if music is playing at a volume of 110 dB in a room, the music behind the wall will be heard at a volume of 70 dB, which is quite loud. Walls with such sound conductivity are said to be paper thin.

 

In a home theater with a standard design, the plasterboard walls vibrate. The vibration is transmitted through the fasteners to adjacent walls and ceilings. So the sound that you hear from the rooms adjacent to the home theater mainly passes through the fasteners connecting the walls, or beams in the case of the ceiling. Sound also penetrates through electrical outlets. And through other unsealed openings in walls, as well as through seams and hairline cracks.

Some see the solution as adding a second layer of drywall or a layer of fiberglass and other soundproofing materials. But, the improvements will be minimal since the sound will still be mainly transmitted through the fasteners.

Another common misconception is using acoustic panels for soundproofing. Acoustic panels are designed to control sound reflections in a room but do not block sound in any way.

It seems like all the options out there aren’t delivering the desired results, so what does it take to soundproof a home theater well?

Concepts of sound insulation

 

Sound insulation is based on three concepts: mass, absorption, and separation. Varying degrees of sound insulation can be achieved by adding mass, damping wall surfaces to eliminate vibrations, and, most importantly, separating structures so they are not physically touching. Ideal home theatre soundproofing is a combination of these three parameters. Proper mass, vibration absorption, and appropriate decoupling of structures give good separation between spaces.

Let’s take a closer look at these key points.

Mass

The most common way to add mass to a wall is to add another layer of drywall. The heavier the wall, the less capable it is of transmitting sound. But, as noted earlier, simply adding a second plasterboard wall cannot completely solve the soundproofing issue.

Absorption

The idea of ​​absorption is to attenuate sound by reducing the level of vibration transmitted to the walls and ceiling of the room. Which in turn will reduce the transmission of sound through fasteners and beams to adjacent rooms. For absorption, soundproofing plasterboard is used. It uses viscoelastic compounds to absorb sound and vibration.

Acoustic drywall with insulation does a decent job of blocking mid-range sound, but it can’t handle bass.

Absorption and mass

For sound insulation, a special barrier is sometimes used, often called a membrane, which is a rubber sheet with metal particles. This layer simultaneously adds mass and absorbs sound. While drywall is a rigid material that vibrates and resonates, the membrane does not transmit vibration and is also a fairly heavy material. Typically the barrier is attached between layers of drywall. The distance between the drywall and the wall is filled with a special sound-absorbing material.

Separation

Adding mass to the walls and ceiling and reducing vibration provides a good start in soundproofing. But there’s more to it than that. It is necessary to separate the drywall and framing, preferably on the home theater side. So that the sound cannot travel throughout the house. This is quite a complex process because you will have to make two walls opposite each other with two sets of fasteners and a gap between them. Only in this case will it be possible to eliminate the penetration of bass beyond the home theater. The main purpose of this double design is to create an air gap between the outer and inner layers of drywall. This air gap prevents bass transmission. Which is why it is so important that the layers of drywall do not touch. This approach will lead to excellent sound insulation.

 

As a result, we have a soundproofing “pie”, usually ranging from 7 to 12 cm. We assembled the frame using specialized vibration-isolating structures, filled it with absorbing material, and covered it with soundproofing plasterboard. If we install a soundproof door, our efforts will not be in vain.

Soundproofing an existing home theatre

If it comes to upgrading an existing room, you should be prepared for the room to lose space due to additional walls. But the result is worth such sacrifices. In addition to excellent isolation, another benefit will be a better-sounding home theater space itself. The interior walls of your home theater will be less rigid than standard walls, so they will absorb bass instead of reflecting it, significantly reducing standing waves. This way, the problem of bass, where it is quite loud in one part and quiet in another part of the home theater, will be eliminated or noticeably reduced. As a result, you will get a room with dense, energetic bass, because the walls will no longer act as reflectors.