With hard metals and industrial aesthetics dominating restaurant design trends, managing acoustics has become increasingly challenging.

Concrete floors, the removal of soft furnishings and open kitchens are creating more than the typical ambient noise, and those added decibels could be taking diners elsewhere.

When people are looking to get to know their date or hold a business meeting at a restaurant, noise levels count.

In cities where non-native speaking tourists abound, acoustics are even more important, along with the need to cater for the hearing impaired.

Noise is a regular complaint according to the Zagat Dining Trends 2015 survey (US). According to those surveyed, the number one irritant when dining out was service (26 per cent), followed by noise (24 per cent), prices (17 per cent) and crowds (13 per cent).

Of course, when noise adds to the ambiance, this can attract diners, so it’s about managing the good noise.

The New York Times recently reported on the echoing design of restaurant Untitled, which is on the ground floor of the Whitney Museum of American Art.

“The primary walls are glass,” Jeff Gordinier wrote. “That back wall is concrete. The floors? Blue Catalan limestone. The cooks chop and sear in an open kitchen, and the tables don’t have tablecloths.”

Toby Stewart, an architect from Renzo Piano’s organisation, who worked on the space with Danny Meyer’s Union Square Hospitality Group, acknowledges that with the lack of soft furnishings and concrete and stone in the restaurant, acoustics was a challenge.

The refurbished Untitled. Image via The Rockwell Group

The refurbished Untitled. Image via The Rockwell Group

So Untitled has been refurbished with furniture, including red felt upholstered seats and room dividers, while the celling now features BASWAphon, an acoustic plaster.

“Reverberation has an important impact on speech intelligibility, affecting safety, health, learning, and quality of life,” BASWA’s website reads. “By absorbing sound waves, BASWAphon makes conversation clearer, even in harsh situations, by reducing reverberation time.”

While not a new form of managing noise, acoustic panels remain a key strategy and more materials are being explored, including natural wool.

UK-based The Woolly Shepherd offers panels identified as Class A sound absorbers which are made with 100 per cent natural British wool in combination with wood fibre.

According to the company, the materials “create high-performance alternatives to the standard mineral fibre and foam based products produced by almost every other manufacturer in the world.”

Last year, the company assessed and treated two rooms, a café and a puppy-training hall at the headquarters of the charity, Hearing Dogs for Deaf People, situated in Buckinghamshire.

With many volunteers already dealing with hearing impairment or hearing loss, it was vitally important that the acoustics in both spaces should be brought up to a standard more suited to these users.

Woolly Shepherd panels inside the cafe

Woolly Shepherd panels inside the cafe

According to a release, “the café, the customer’s main priority, has been reduced to a reverberation time of 0.4 seconds (125 to 4,000 hertz) using acoustic clouds right the way around the lower ceiling slopes”

The panels can also be customised in different shapes to suit the décor, though the classic cloud designs remain popular.

Australian company Pyrotek Noise Control (NC) creates sound absorption products. In 2013, Pyrotek installed its Echohush panel range in the Dux Dine Restaurant in Christchurch. These panels were designed to suit the decor and reduce noise levels in the hard-surfaced dining room, which was affected by the “Café Effect” – noise generated by customers who subconsciously raise their voices to be heard over others.

“…research into the Café Effect showed that, with an average reading of 65 dBA, restaurants had the highest average background noise levels, whilst bars and cafés had readings of 57.5 and 58 dBA respectively,” the company said in a statement. “All three of the average overall background noise levels in Christie’s research were above the recommended maximums for building interiors as set out by Standards New Zealand at 50 dBA for bars and restaurants and 55 dBA for cafés.”

Greenery can also help to manage noise. Trees and plants have been used for years in the urban environment for noise pollution and in apartment buildings for acoustic performance.

Studies have shown that the leaves of plants are able to accentuate and reflect sound depending on the number of plants in the space and where they are positioned.

Earlier this year, agriculture engineer Zaloa Azkorra of the University of the Basque Country’s Department of Thermal Engineering conducted a study on the benefits provided by green walls, including acoustic insulation and absorbing noise.

The study was carried out within a reverberation chamber in two different laboratory settings that follow international standards. A modular green wall was used.

Azkorra concluded that “the green wall showed a similar or better acoustic absorption coefficient than other common building materials, and its effects on low frequencies were of particular interest because its observed properties were better than those of some current sound-absorbent materials at low frequencies.

“The main results were a weighted sound reduction index (Rw) of 15db and a weighted sound absorption coefficient (a) of 0.40. It could be concluded that green walls have significant potential as a sound insulation tool for buildings but that some design adjustments should be performed, such as improving the efficiency of sealing the joints between the modular pieces.”

Other traditional ways to manage noise is to double-glaze glass windows and work with soft furnishings. Installing carpet or an insulating layer of flooring, window furnishings, tablecloths and fabric furniture can make a world of difference to acoustics.

In 2013, Sam Fletcher, an acoustic expert and director at Soundblock Solutions suggested strategies as simple as placing rubber caps on chair legs and managing background noise.

Speaking of background noise, 2015 study The Acoustics of places for social gatherings by JH Rindel, notes that the effects of noise greatly depend on the hospitality space. Noise can affect a diner’s experience, including what they spend.

“For the owners of the restaurants it may be interesting to know that the perception of food and drink is influenced by the ambient noise in the room,” Rindel wrote. “In a fine restaurant the noise should be kept at a low level in order to maintain the taste qualities in the food. But for the owner of a bar, where the guests mainly come for drinks, a noisy environment means that more drinks are consumed in a shorter time.

“…When music is played in restaurants or at social gatherings, it is necessary to distinguish between background music and foreground music. While foreground music is mean to catch the attention, background music should not interfere too much with the quality of verbal communication, and a sound level up to 60 dB is suggested.”