BERNE — It probably has happened to you one time or more. While you're walking somewhere in a city, you suddenly feel the desire to stay a while longer in a particular spot. And for no obvious reason. It's just a place among others, maybe a greyish alley or non-descript city square.

And yet, something invisible about that spot gives you a sense of well-being. The sound of rustling leaves. The birds singing. The lapping of a water fountain. The charm, it turns out, isn't something you can see or feel. It's what you hear — the soundscape.

"We pay a great deal of attention to building good acoustics in concert halls," notes Fabian Neuhaus, an acoustician. "But when it comes to urban design, the sound dimension is still usually overlooked. But poor acoustics in a public space cause dissonance and an annoying cacophony just like an ill-conceived hall."

Neuhaus runs a firm that specializes in "sound architecture." The company, based in Solothurn, Switzerland, mostly works on upgrading the sound quality of industrial buildings and concert halls. "But outdoor spaces also need to be properly "tuned" to produce pleasant sounds," he says. "Unfortunately, it's rarely a priority in an urban project."

The acoustician's assertion is confirmed by a 2015 report from the Swiss Federal Council. The visual aspect takes precedence with regards to design and budget; acoustics are largely ignored, and the study concluded that noise-reduction measures have to be taken later on.

But things are changing. Densification and a desire among city dwellers for a better quality of life are encouraging public authorities to take acoustic features in urban design more seriously.

The cantons of Bale and Zurich are taking the lead. Both asked Neuhaus' firm to offer guidelines for a well-designed soundscape along local roads. The way buildings are positioned and their proportions, for example, have repercussions on reverberations caused by traffic noise. The shape of buildings matters too: They shouldn't lean forward too much.

"Instead of fighting against noise pollution afterward, we should include the acoustic dimension in the project from the very beginning," the Swiss acoustician says. "Rather than enduring noises, we should control sounds."

In Zurich, urban planner Trong Maag works hand-in-hand with his associate Andres Bosshard, a musician and expert in sound architecture. Their project, called Urbanidentity, aims at identifying spaces with pleasant acoustics, analyzing their advantages and offering solutions for greater sound quality for future projects. General layout, floor surface, facades and even decorative elements all need to be taken into account, they explain.

"A path covered with gravel or sand will produce a soothing rustle while trees will act as a sound barrier, and a green wall will absorb high-pitched sounds instead of amplifying them," says Maag. "Nothing is worse than large uniform facades made of glass or steel, which are a real torture for our ears."

At the behest of the cities of Bale and Zurich, and their surrounding regions, Urbanidentity suggested 13 golden rules that establish sound quality in urban environments. But these rules would have to be applied during redesigns or at the early stage of development of new projects. Though still rare, at some point Bale and Zurich may aim to impose these rules as a condition in public tenders.

Controlling noises is not about putting up walls

Lausanne architect Blaise Arlaud, who works for the firm EcoAcoustique, agrees that acousticians should be brought in early in any urban design project. "In most cases, they are restricted to issues concerning regulatory compliance or noise control, when they could go beyond that and actually appropriate sounds," he says.

Building in accordance with sound is the dream of Pascal Amphoux, another architect from Lausanne. "Controlling noises is not about putting up walls but rather designing adequate arrangements," says Amphoux.

With structural designer Filipo Broggini, he has developed a new concept of anti-noise modular screens, with flexible acoustic correction. In his project for the viaduct of Chillon, in southwestern Switzerland, the screens are shaped like wings that unfold, following the arches and rhythm of the surrounding sounds.

Other examples where designers prioritize sound include Andres Bosshard's singing fountain, located in a schoolyard in Zurich, and the sonorous duckboard in a park in Lyon, France. The duckboard was designed by architect Cécile Regnault, a teacher at Lyon's National School of Architecture.

"In an ideal project, sound and image would be complementary," says Regnault.

For now, the rare installations that put sound as a high priority are still a touristic curiosity. In Zadar, a coastal city in Croatia, installations by the sea include the world's only marine organ: When the waves rush into an ingenious pipe system, they compose an ever changing symphony. In Switzerland, a musical bridge designed by Max Neuhaus is hiding in the streets of Berne. And in the German city of Dresden, a complex of buildings makes the rain play an orchestral score thanks to water pipes that are fixed on the facades.

"Perhaps one day acoustics will be an integral part of urban design and we will create something with sound rather than just block noises," Bosshard says. "We have to keep in mind that in a city, sound is central to our sense of well-being."