8 Tips on Improving Room Acoustics

How do I optimize the sound in a room / studio?  

How can I prevent booming basses or flutter echoes?

Be it for an optimal listening situation or good audio recordings: In addition to good studio monitors, the room acoustics, in particular, is crucial for a good sound. Fortunately, the room acoustics can usually be improved so that flutter echoes, wandering phantoms, and booming or too thin shots will soon come to an end. Our simple tips can help you to optimize the acoustics in the home recording studio without much cost.

Welcome SEA fans to another blog post on Tiptuesday and as promised in the previous tiptuesday post discussed on tips and common mistakes on setting up studio monitors, today we are discussing how to sound better inside a room/studio.

Improving the room acoustics often brings more sound gain than acquiring new components. Check your playback quality and improve the sound with our step-by-step instructions and free “home remedies” / ready-to-use room acoustics.

The equilateral stereo triangle between speakers and listener is secured basic knowledge. But the interaction between room acoustics and the installed hi-fi system is quite complex. It is, therefore, worthwhile to analyze the weaknesses of the listening room and to optimize them step by step.

1. Reduce the reverberation time

The more hard, reflective surfaces (stone, concrete, parquet, glass, etc.) in an open space, the more the room will echo. A good clue here is the reverberation time, which can be heard by clapping: the longer the reverberation “resonates” or even short, snarling echoes are heard, the higher the reverberation time. Materials that absorb sound, at least in certain frequency ranges, help reduce it: upholstered furniture, carpets, curtains, drapery panels, open, filled bookshelves.

But beware: Many materials such as wood and thin fabrics only significantly dampen the highs, but leave mid and bass almost unaffected. Then the reverberation appears darker and warmer, but when playing music, it can sound uncomfortably potty and blubbering. In this case, only thicker absorbers such as foams will help you out, which also dampen the mid-tone and you can hide behind pictures or ceiling coverings.

Those who prefer thicker and denser materials from the beginning – such as fabric sofas, deep pile carpets, bean bags, foam ceiling panels and heavy / multi-layer curtains – have a much better starting position.

2. Provide diffusion

From sound reflections on a single surface, which arrive concentrated and shortly after the direct sound of the listener, the ear can be irritated more than from a uniform Hall field with multiply reflected sound components. Likewise, echo-like reflections, which run back and forth in regular intervals between two walls, are significantly more disturbing than chaotically distributed in the room.

If you can equip your room from the outset with sloping walls or obliquely placed cupboards/shelves, you have the advantage. Even large open bookshelves, plants with large, hard leaves (like palm trees) or winding, open shelves sometimes work wonders. In contrast, glass showcases or cabinet systems with a smooth, continuous front are problematic.

3. Avoid echoes

Reflections that move back and forth between two parallel reflecting surfaces are harmful to the impression of spatiality. The best way to go after the “Live End / Dead End” concept: If a wall is unclad, should be designed on the other side over a large area absorbent, such as a bookshelf or porous absorber. If the ceiling is hard as sound, a large high pile carpet will help.

4. Create symmetry and reduce sidewall reflections

For the quality of the stereo reproduction, it is important that the left and right boxes are placed in a similar acoustic environment. Above all, the side walls to the left and right of the speakers as well as the floor between the box and the listening position are crucial, because this creates the first reflection that reaches the listener directly after the direct sound.

For example, if one loudspeaker is next to a large glass surface and the other is next to a free passage, a bad image and disturbed spatiality is almost always the logical consequence. A rotation on the balance control does not help here because of the distorted sound field in terms of time and frequency dependence. One should, therefore, think about how to set up the boxes as freely as possible with the same distance to the side walls.

If there is a bookshelf next to the left box, it makes sense to place an acoustically similar shelf next to the right one. If the two side walls are free of furniture, it is advisable to place a foam absorber or an absorber picture right next to the loudspeakers where the first sound reflection occurs according to the rule “angle of incidence = angle of failure”.

If the symmetry cannot be established and the mono-test does not produce a satisfactory result, rearranging the furniture and the system is often a good idea. For example, you can rotate the entire positioning 90 degrees in space.

5. Create space or cushioning behind the listener

Hearing places in front of a wall is acoustically unfavorable for several reasons: Here, not only the booming room resonances but also discrete reflections gather. A listening position with 50 centimeters, better one meter and more in front of the back wall, usually sounds more balanced clearer and more spacious. If this is not possible, a diffuser or absorber should be installed behind the receiver, or at least a bookshelf or plants with large, thick leaves.

Hope you have found the above-discussed topic useful and we are inviting suggestions/updates on improving this post as comments in the box below.

6. Wall, shelf and bass

The closer the speakers are to the wall behind them, the more the low bass is raised. At the same time, the dreaded room resonances are more stimulated when between box and back wall is only 90 centimeters or less space. The situation will become more extreme when compact boxes are placed on a shelf. If the bass is in any way too fat, droning or playing “slowly”, it means: Move boxes away from the wall until the bass becomes more precise.

Bass-compatible compact boxes belong on a stand and not on the shelf. If you are looking for the optimal positioning for the bass, you can use the bass backward trick. In extreme cases, if sufficient wall clearance is not feasible, it can also be attempted by closing one or more bass reflex tubes (compacted material or foam).

7. Stereo triangle and listening distance

For both 2-channel stereo and multichannel, the front speakers should form an approximately equilateral triangle with the listener: the distance from the listening position to the left should be identical to the distance to the right speaker (tolerance less than five centimeters), the distance between the two Boxes may vary slightly (+/- 10%). How strong and in which direction, one should find out by listening experiment.

First, it is important to find the optimum hearing distance: A smaller stereo triangle (below two meters is called the distance from the near field hearing) often ensures a very good tracking sharpness but leaves the room to appear small and limited. On the other hand, an excessively high listening distance often sounds diffuse, washed out and superficial, voices are increasingly difficult to locate. The ideal compromise can best be found with the mono-test: starting from a small stereo triangle, you determine the positioning accuracy and then move the speakers away from the listener in steps of 15 or 20 centimeters. The ideal listening distance is usually where the central location is just stable and sharp.

Owners of bundling loudspeakers such as horns or electrostatics have a better life here: they also make it possible to find a good location even at a considerable distance.

8. Angling for professionals

Should the boxes be set up parallel to the wall or be infiltrated at 20, 30 or even 45 degrees? The angling influences 3 playback criteria: the tonal neutrality, the image accuracy, and the spatiality. Most speakers emit less sound in the upper mids and highs outside the ideal 90-degree axis.

It is therefore advisable to start the experiments with an installation directed directly at the listener: If the heights are too sharp or if the overall sound is too bright, the speakers must be turned away from the listener – whether outwards or inwards, is for the timbres not decisive. A turning away to the outside to the parallel setup usually increases the impression of space, but can also worsen the locomotion and for other listeners who sit next to the main auditorium, worsen the picture in addition.

An inward angle, ie 35 to 50 degrees to the wall, often improves the tradability, but can lead to a limited space. If several people hear each other next to each other, this is almost always to be preferred in order to enable everyone to get a good central location.

Hope you have found the above-discussed topic useful and we are inviting suggestions/updates on improving this post as comments in the box below.

Happy Sound Engineering !!!

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