Bringing the Big Cinema Sound Home - Our Top Tips for Improving Your Home Cinema Sound Experience
The next time you visit your local cinema make it a point to observe and touch the surfaces of the walls of the cinema.
Acoustic treatment plays a great role in making spaces functional and proper application of acoustic design principles will ensure you create a truly immersive space in your home cinema.
Many home cinema enthusiasts keen to bring the big cinema experience home will spend thousands of pounds on the latest projectors, speakers, amplifiers and cables and completely omit the room all this equipment is going to be sat in well apart from ensuring they have the most comfy cinema like seats.
Infact many times home cinemas are built by contractors who may have great design and build skills but have absolutely no idea about how to make spaces acoustically functional for the intended use.
We would always recommend engaging an acoustics expert in advance of your build. However not many people have the luxury of new builds/extensions for their home cinemas, instead resorting to converting an existing room for this purpose. New build, extension or conversion the importance of interior acoustics is often only realised once the space is in use. Bright reverberant spaces, muddy low ends or excessive bass boom degrade the quality of sound in your home cinema and result in a poor listening experience.
If you are looking to bring the home cinema experience home here a few things you must do!
1- Reduce excessive reflections
The reason why your local cinema has absorbent walls carpets and ceilings is because excessive reflections from hard reflective spaces colours sound and impacts on the sound waves being generated by loud speakers. Home cinema 5.1 and 7.1 systems are designed to reproduce sound in a sequence that creates an immersive spacial effect to the listeners, with mirco-second delays and effects introduced to create the illusion of space and distance. In rooms that are not adequately treated these precise effects are drowned out by secondary waves reflecting off the surfaces the sound is bouncing off. Creating a listening experience which can be overwhelming and unsatisfactory.
Treating your walls
Introducing absorption is absolutely critical to improving your listening experience. Ideally you should be aiming to completely eliminate flat reflective surfaces with absorption however in many cases the practical multi-use nature of home cinema rooms makes this impractical. Users should aim for as much absorption as their interior decor will allow anywhere above 40% of the reflective spaces. Acoustic treatment for these vertical reflective surfaces doesn’t have to be thick, 30mm foam panels or 25mm fibreglass panels will more than suffice with 50mm panels strategically placed at primary early reflection points.
Treating your ceiling
For home cinema systems with atmos technology, ceiling treatment should be omitted as the speakers use the ceiling to create depth in the sound being replicated by the speakers. Ceilings in rooms where non atmos speakers are installed should look to introduce absorption equivalent to about 40% of the ceiling area. Again 30mm panels will suffice complimented by 50mm panels at primary reflection points.
Treating your floors
Avoiding hard wooden or reflective surfaces is recommended but where this i not practical then introducing medium pile rugs will help reduce reflections off the floor.
2- Control that bass
Low end rumble in movies is essential in creating an immersive cinema experience. The vibrations of the bass as it fills the room can be used to great effect. However small rooms are not particularly suited to low frequencies. The dimensions and characteristics of the room in many cases interact with sound waves creating standing waves. These waves can be more dominant than sound waves being created by your speakers, which can result in;
Muddy low ends when listening to music or rumbles that aren’t as deep as the sound designer and producer intended them to be.
Excessive boom in your room, creating points where the bass is reinforced and others where it is cancelled out. This excessive boom is created by the presence of bass modes which can degrade your listening experience.
Issues with bass propagation to neighbouring spaces and rooms causing unnecessary disturbance to occupants of neighbouring rooms.
Introducing bass traps into your home listening space will help soak up the energy of these low end modes creating a much more accurate and pleasant listening experience.
The choice of bass traps one goes for will depend on among other things budget, space and decor. At the cheaper end of the bass trap spectrum are acoustic foam bass traps and corner kits which work well and have the added advantage of being easy to mount and available in various profiles. The down side of most foam solutions is, colour options are limited and the dark grey foam creates a studio like feel in rooms which is an issue in multi-use spaces.
Fabric covered fibre glass or mineral wool bass traps perform better and are more expensive, however, offer the user a choice of colours of the fabric which can be used to complement or match existing decor. Bass traps of up 100mm thick will suffice with typical lengths of between 900 and 1200mm.
Placement of bass traps
It is a well know fact that bass energy builds up at points where two or more significant surfaces meet. The significance here being in relation to the wavelength of the bass frequencies. As such bass build up happens in corners and edges of rooms. It is important to install bass traps in or as close as possible to corners first and then work your way along the vertical and horizontal edges of the room.
Quantity of bass traps
Whatever option you choose the idea is to try and get as many bass traps into your corners and edges as are required to improve the low end in your room.
It has been said you can never over bass trap a room and this holds true for most home cinemas especially if your bass traps are concentrated at the points of maximum bass build up i.e. corners and edges.
3- Diffuse your sound
Diffusers are acoustic treatment elements that scatter sound waves that are incident on them. This has the opposite effect of absorbers in that, instead of absorbing the sound and converting it into heat energy and reduce the overall sound energy in a room. Diffusers on the other hand scatter incident sound waves reducing their significance whilst maintaining the overall sound energy in a room. Diffusers have an acoustic effect of broadening sound out creating an acoustic effect of spaces that are larger than they actually are.
Scatter plates may be combined absorption cores to create a diffuser that absorbs and scatters sound. These diffusers work really well in small spaces where both effects are desirable.
Placement of diffusers
Diffusers work best at their optimum listening distances however in our experience we have found that our diffuserflex panels are best placed in areas where the reflective surface is less than a meter away from the listener. This creates a spread of sound around the listener transforming they listening experience when compared to having absorption or no treatment on these surfaces.
Some diffuser panels can also be straddled across vertical corners, where the air gap between the panel and the corner lowers the frequency at which they start to be effective acting as bass traps.
Quantity of diffuser panels
Once the surfaces closest to the listening position have been identified a run of diffuser panels placed just above listening height or above the height of seating will suffice. If used as bass traps a vertical run from floor to ceiling works well. If used to treat early reflection points it is important to maintain symmetry in the room with panels on the left mirrored on the right.
A final word on acoustic treatment of home cinemas. It is important to note that a room that is optimally treated is a listening paradise however if done post build or retrospectively this comes at the cost of aesthetics in the room. Acoustic treatment can look clunky and industrial. The user will have to strike a balance between quality of sound in their home cinema and aesthetics, working to balance the two especially in multi use spaces.
If you are fortunate to be at the stage of embarking on building or converting a space into a home cinema then many solutions can be incorporated into the build. Bass traps, absorption panels and even speakers can be mounted flush with your walls introducing optimum acoustic treatment without intruding on the aesthetics and decor of your room.
If you would like to see how our acoustic treatment can be incorporated into your build project fill out the form below and we will be only too happy to help you.