Tag Archive: sound absorption

  1. 4 Restaurants with Great Acoustic Design

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    As perceptions of what constitutes luxurious environments and trends in food service have evolved, restaurant design has more and more favored large, open spaces and hard surfaces. And this is having a serious effect on restaurant noise levels. Acousti Banners in Restaurant

    In the race to create sumptuous and modern aesthetics, many of the decorative features which used to provide organic sound absorption have fallen out of fashion. Higher-end dining environments used to be lush with carpeting, table cloths, and wallpaper, but now polished granite counters, marble table tops, ceramic or hardwood floors, open kitchens, exposed brick, and bare walls have taken over.

    The surge in highly-reflective surfaces has led to serious noise problems for restaurants and their customers. Certainly, a bustling atmosphere can be desirable and inviting – after all, nobody wants to eat in a mausoleum – but, quite often, the noise in restaurants can be literally deafening. So, it should come as no surprise that restaurant noise control is an increasingly important subject in the food and hospitality industry.

    Normal conversation works best between 55 and 65 decibels, but typical restaurants can rate as loud as 85 to 100 decibels – that’s on par with your average jackhammer or a jet taking off. Bear in mind: beyond 75 decibels conversation becomes difficult, and at 85 decibels, inner ear damage can lead to permanent hearing loss.

    For the more than 1 in 10 Americans who suffer partial or severe hearing loss, this can make dining out a non-starter. According to the 2018 Zagat Dining Survey, noise topped the list of customer complaints. In fact, many restaurant critics now bring decibel meters with them and include acoustic quality along with ambiance, service, and food quality in their restaurant reviews.

    Balancing Sound Absorption in Restaurants

    Sound absorption solutions for restaurants require a balancing act: diners want a comfortable level of noise that will allow them to enjoy conversation, while restaurant owners still want some level of noise to ensure a perception of popularity and enjoyment within their establishments.

    4 Restaurants’ Solutions for Acoustical Issues

    1. CōV Wayzata, Wayzata, Minnesota

    CōV Wayzata features an open kitchen and bar, and it could get uncomfortably noisy during peak business hours.

    To absorb and disperse sound, they raised the ceiling and installed a mix of acoustic panels and wooden slats. They’ve left the kitchen and bar open, but the noise these areas generate provides background ambiance which helps guard patrons’ conversational privacy while enabling them to speak with each other at comfortable levels.

    2. Oliveto, Oakland, California

    Oliveto also features an open layout in which both the bar and kitchen are open to the dining area. The owners didn’t want to simply reduce noise, so they employed a two-fold solution that enables them to directly control the acoustics according to how busy the restaurant is.

    First, they installed a passive acoustic system in the ceiling made from sound absorbing tiles. They also installed a combination of microphones, signal processors, and small speakers – all discreetly incorporated within image panels and complementing the overall aesthetic. Using an iPad, they can now directly shape the acoustics of the restaurant to make it sound busier at quiet times and to lower sound levels when the restaurant is busy.

    Silk Metal is another fantastic product that’s easily installed into drop-ceiling T-grids. It works on a wide range of frequencies, and it boasts an NRC of 0.80. Since it’s made out of aluminum and not fiber-based, it can also be steam-cleaned, and this should make it a very attractive option for restaurant owners since hygiene and sanitation figure so prominently for them.

    3. Untitled, New York, New York

    Untitled consists of a wide-open space with high ceilings, walls of glass and concrete, and limestone flooring. It also features an open kitchen, and there isn’t a tablecloth in sight. By all accounts, you’d expect the restaurant would reflect and amplify every sound, and yet conversation is heard crisply, without distractions from music, background noise, or voices from neighboring tables.
    They’ve coated the ceiling with a porous acoustic plaster called Baswaphon. It absorbs sound much like a sponge soaks up water, so the restaurant retains its distinct, contemporary aesthetic without descending into ear-splitting cacophony.

    Similar to Baswaphon, Microperf micro-perforated panels represent an entirely new class of decorative sound-absorbing wall and ceiling panels. These decorative panels provide exceptional acoustic performance in tandem with pleasing design features that can be easily incorporated into any aesthetic.

    4. Boba Latte, Richardson, Texas

    Boba Latte specializes in tea, coffee, and smoothies – the kind of environment that lends itself to quiet conversations or reading. Their minimalist design, however, caused unwanted echoing, and the owners wanted to create an acoustic environment which would allow for casual conversations while allowing customers to relax and enjoy their time there.

    Solving the problem required a slight change to the restaurant’s aesthetic. They installed colored acoustic tiles on a wall at one end of the restaurant that now acts as a sound absorber as well as serving as an attractive accent to the overall white-on-white color scheme.

    echo eliminatorAnother very affordable, high-performance solution in this type of scenario would be to use Echo Eliminator™ sound absorbing panels. They’re made from recycled cotton, and they can be used easily attached to wall panels or suspended from ceilings as hanging baffles. They’re as effective as fiberglass, and they contain no volatile organic compounds.

    For another great, high-performance sound blocker and absorber, try the STC and NRC rated Sound Silencer™ panels. They’re affordable, Class A fire rated, and they resist moisture, impact, bacteria, and fungi. They can be employed in both ceiling and wall applications, and they’re great for food-related environments.

    Conclusion

    Shaping restaurant acoustics is as important as establishing décor, service, and food quality, and each restaurant owner should understand the wants and needs of their prized customers. While this may be a challenge, there is no shortage of dynamic, affordable, and aesthetically attractive solutions. Visit Acoustical Surfaces to view our full range of acoustical products or to get customized solutions and products for your restaurant.

  2. What is Sound Diffusion (and Absorption)?

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    Here’s an easy definition: diffusion is the method of spreading out sound energy with a diffusor (diffuser) for better sound in a space. However, in the wide, wide world of acoustics, the sound diffusion process and tools are widely misunderstood, even by some acoustics professionals. This seems a bit odd, because it’s one of only two tools in our “Better Sounding Room” toolbox.

    That’s right – there are only two acoustical tools available to improve sound inside a room, whether that room is huge or tiny: sound absorption and sound diffusion. Both tools will improve sound perception in spaces that, if left untreated, would be a bad influence on sound. In large acoustically-designed spaces, like concert halls, diffusion is most often built into the room’s physical geometry – the shapes of walls and ceilings (floors are nearly always flat and act as large flat-surface reflectors, even if sloped).

    Keep in mind that absorption and diffusion are NOT the same as the methods used to reduce sound leakage into and out of a room, usually called “soundproofing,” which results in “less noise” (noise defined as any unwanted sound). Absorption and diffusion are called room treatments and are used for “better sound”.

    Why would we need better sound in rooms? Because most walls, floors, and ceilings are made up of hard, flat surfaces which strongly reflect sound energy intact. These strong, intact reflections cause problems when they’re-combine with the original sound, which arrives at our ears directly through air without reflecting. Because the reflections are traveling farther, they are delayed compared to the original sound (see Fig. 1).

    Multiple delays from many flat surfaces, combined with original sound, add too much echo and reverberation. Equally problematic, delays from sound reflections cause timing (or “phase”) errors – these disrupt sound-stage imaging and cause frequency additions and subtractions called “comb-filtering” (from the shape of the resulting frequency-response peaks and dips). Accurately hearing original sound, whether from voices, musical instruments, or loudspeakers, becomes difficult. Too much intact reflected sound energy causes sound in rooms to become unwanted, uncomfortable, and unavoidable noise.

    speaker sound bounce

    Figure 1 – Original sound: red lines; reflected sound: blue and green lines

    Because absorption is the one process many people think of when referring to acoustical treatments, let’s look at an easy definition of sound (acoustic) absorption before looking at diffusion: acoustic absorption is the process of reducing sound energy (see Fig. 2), as opposed to reflecting sound energy. The absorbed sound energy is not equal across all frequencies, however, usually causing a shift in tonal perception, with higher frequencies the most easily absorbed. Most often, an absorptive panel of fibrous material (fiberglass, cotton, mineral wool, wood wool) is placed in a room on hard, flat sound-reflective surfaces to reduce the energy “bounced” back into the room.

    speaker sound absorber panels

    Figure 2 – sound reflection energy reduced with absorber panels

    Manufacturers of fiber-based panels often tout them as the only solution, and in some situations, like gymnasiums, restaurants, and churches, absorber panels may be the only room treatments needed. Additionally, these panels are economical and widely distributed. In practice, though, it is possible to have too many absorbers in a room, causing a perceptual disconnect between mental expectation of what the sound in the room will be like and an “overdamped” acoustic reality. Overly-absorbent room treatments can cause their own set of problems in some spaces.

    A balance of absorption and diffusion is better for critical-listening rooms. Adding diffusion (see Fig. 3) keeps enough energy in the room to sound more natural while spreading out some of the reflected energy. Additionally, diffusion can give the impression of a larger space, which is good for smaller listening rooms. More well-trained listeners – such as recording engineers and audiophiles – usually aim for a 50% mix of absorption and diffusion.

    sound diffuser

    Figure 3 – curved-surface diffusor panels evenly spread sound energy

    As mentioned earlier, many people think absorption is the only available room treatment. Likewise, some people think there is only one type of diffusion product – the Quadratic-Residue Diffusor (QRD). QRD treatments rely on shifting the timing, or phase, of the reflected sound to spread the energy. They are most often used on the back wall of listening and control rooms, because the phase-disrupted reflections exhibit lobing (uneven frequency distribution) and create sound-stage imaging problems when used in first-reflections points on the side and front walls. Pyramid- and cube-shaped reflectors are also used as diffusion elements, but these types of reflectors are best used at a farther distance from listeners than curved or spherical diffusors due to their flat reflective surfaces.

    Which brings us to geometric shapes used as diffusors. The two best diffusor geometries are “slices” or sections of cylindrical and spherical shapes, because they evenly spread sound energy within a space. Additional benefits of these shapes are that the spread-out reflections are broadband, affecting a wide frequency range, and the evenly-reflected sound is phase-coherent, meaning the timing signatures contained in the original sound are preserved as much as possible. Cylindrical and spherical shapes have a constant radius, ensuring the sound is spread consistently regardless of the incident angle (the direction of incoming sound waves). Sphere shapes diffuse in two dimensions (height and width), where cylinder shapes diffuse in either width or height, depending on orientation.

    Diffusion is now gaining wider acceptance as an extremely useful and natural-sounding option for helping problem rooms sound much better. Affordable cylindrical diffusors are being produced from curved aluminum, offering a wide array of finish colors and styles, by incorporating fabric, automotive paints, and wood veneers (see Fig. 4). Placed on walls and ceilings at first-reflection points in listening and recording rooms, phase-coherent cylindrical sections really improve the sound – and décor – in nearly any shape of room or space imaginable.

    sound diffusor

    Figure 4 – curved-surface diffusor finish options