Have you ever wondered what the difference is between sound frequency and sound level? Do you know what the Lombard effect is? If you don’t have a clue, don’t worry, because today we’re carrying on with our Jargon Buster series.
In the last article, we broke down lighting industry jargon. This time, we’re talking about six of the most common terms used in acoustics. As always, we promise to avoid the overly complex, scientific mumbo-jumbo. Let’s start!
What is sound itself? Sound is a variation in air pressure that ears can detect. A sound source (for example, your mouth while speaking) emits air pressure changes that travel as a sound wave at a speed of approximately 340 meters per second. When energy from the sound source reaches the eardrum, sensitive bones within it vibrate, and the auditory nerve signals to the brain that we’re hearing something.
Did you know?
Sound waves travel much faster in water than they do in air. Sound travels 4.3 times faster in water than it does in air of the same temperature. That’s why water animals, like dolphins, can communicate over such long distances (up to 10 kilometers).
dB, or decibel, is the unit of measurement for sound pressure. It refers to what we perceive as “loudness.” So, when acoustics professionals talk about how “loud” a room is, they are referring to its decibel level. What’s most important to know here is that sound pressure isn’t measured on a linear scale because an ear’s reaction to changes in sound energy is not linear.
For example, in very quiet surroundings, even a tiny change in sound pressure is noticeable and enables us to hear a change in loudness. In a very noisy space, on the other hand, we need to increase a sound’s energy level much more to detect the difference. That’s why a decibel scale is not linear; it better mirrors the function and characteristics of our ears. Here’s another example: to increase the sound level by 10dB—from 40dB (a small refrigerator) to 50db (an average conversation) — we need 10 times more sound energy. A 10dB increase corresponds to a doubling of loudness.
Did you know?
The term “decibel” is derived from the name of Alexander Graham Bell, the inventor of the telephone.
When a sound wave strikes a hard surface, like concrete or glass, it is reflected and gradually loses its energy. This results in an effect called reverberation. Reverberation time is the length of time that it takes for a sound to reach complete silence after its initiation.
In rooms with excessive reverberation, we often feel uncomfortable, especially during longer conversations. Give it a try. How does a 4-way conversation in a small bathroom sound after a while? You will quickly notice that the words you hear are unclear and seem too loud. That is because different sound waves mix together as they are reflected by the hard materials in the room. Sometimes, to be heard better, you instinctively raise your voice, but it only makes things worse.
To prevent that effect and to communicate more clearly, you can make sure that office spaces, like conference rooms and rooms dedicated to making video calls, have short reverberation times.
Did you know?
The optimal reverberation time depends on the intended use of a room. For a conference room, it is recommended to keep the reverberation time between 0.5 and 1.0 seconds. In open spaces, the reverberation time should be lower, between 0.4 and 0.6 seconds, because there are more potential sound sources. Keeping the reverberation time in a big conference room too low, however, can also lead to some acoustic problems. For example, those in the back of a room might struggle to hear a speaker at the front.
Noise is a general term to describe all unwanted, unnecessary or disruptive sounds, such as background chatter, alarms, telephone conversations, buzzing electronic devices and sounds from the street. Being in a noisy environment can reduce concentration, increase workplace risks and, in the long run, even create health problems.
Did you know?
The energy of an acoustic wave can be absorbed, reflected, or transmitted. The extent to which the energy is absorbed, reflected, or transmitted depends on the barrier’s material composition. Hard surfaces (like concrete or glass) reflect acoustic energy, whereas porous materials will absorb most of it. To reduce the noise level, you have to absorb as much sound energy as possible by using specially designed porous materials.
Sound absorption is the ability of a given material to partially block the energy of a sound wave and turn it into unnoticeable thermal energy. Sound absorption is used mostly in products dedicated to limiting the reverberation time inside a room. By placing sound absorbing materials on walls, ceilings or in corners you can make your room quieter and cozier.
Absorption is measured according to the ISO 354 norm and expressed as the sound absorption coefficient αw, with a value between 0 (total reflection) and 1 (total absorption), and corresponding classes A–E. Class A represents the highest quality and E, the lowest:
Did you know?
Five of our products have Class A sound absorption properties, which means these products offer top-quality sound absorption that effectively reduces reverberations that could cause distraction:
To put it simply, sound attenuation describes a reduction in sound volume. A product that supports sound attenuation, therefore, helps reduce the energy of a sound wave as it travels through a particular space (for example, the voice of a chatty colleague from another department in your open-plan office). The rule is simple: the more you reduce the sound in different parts of the space, the more (acoustically) comfortable the space is. This comfort supports productivity because it can reduce noise and distraction. Acoustic products like walls and partitions provide high-quality sound attenuation. Instead of absorbing sound, they capture it, acting as acoustic barriers between different areas of the room.
Did you know?
We offer a wide range of products that support sound attenuation:
The Lombard effect describes our tendency to increase the volume of our voice in a loud environment. We do so because we think that we will become more audible to others. What’s interesting is that the change occurs in both loudness and other acoustic features like pitch rate and syllable duration.
Did you know?
Research on birds and monkeys has demonstrated that the effect also occurs in the animal kingdom.
Now that you know the acoustics essentials find out how to improve office acoustics with these Mute products. Or check out our article, “Well-Being Boosters: 4 Reasons to Improve the Acoustics in Your Office”, to see how acoustic solutions can influence your team’s well-being and productivity.
Noise and distractions can be tough on employees at busy workplaces that have to focus on their tasks. Given the fact that we lose about 66% of our productivity only if we hear someone talking around us. Further studies have even found out how much time per day we lose due to distractions: 86 minutes. An unbelievable number, especially if we think of the usual 8-hour full-time job. So what are the next steps for offices now? You need to find simple solutions to catch sounds before they can be jumping around the workplace. Maybe you want to consider the following solutions.
Before you bring the entire interior to your new office, make a smart plan and consider the needs of all teams
5 Ways to Reduce Noise in a Busy Office
While you’re sitting at this really important project, you just can’t put your mind to it when you are constantly hearing others discussing a task or being in phone calls. Especially in open office spaces, it is hard to find some peace and quiet for focused work. Let us give you five simple ideas to absorb the typical office sounds.
1. Be Smart When You Arrange the Office Space
Let’s start with the basics. When you place desks for employees, consider putting the teams and people who constantly work together close to each other to communicate easily. You can separate the room into compact spaces by placing acoustic walls so one team does not disturb another.
Put printers and other office machines in a separate room. The noise of those machines can be very distracting and even annoying for employees, as the sudden sound steals their focus and reduces their productivity if they always have to find their way back into the task. Do the same with coffee machines, kettles, and microwaves. Place them ideally in the office kitchen without the cool coffee bar in the middle of the office. You can also place some sound absorbing panels in the kitchen as it is often the loudest place in the entire office.
So before you bring the entire interior to your new office, make a smart plan and consider the needs of all teams, e.g. don’t place the always bubbly and chatting creatives next to the accounting team.
2. Perfect Plant Placement
Place plants all over your office space - the bigger, the better, because bigger plants can catch more of the surrounding noise. Besides the much-needed sound absorption, plants are beautiful to look at, make the space more homey and comfortable and create good vibes. It is proven that plants have a positive impact on our mood. Not only that, but they also increase the air quality and help to keep a clear mind.
3. Create Quiet Work-zones
Some people have a more challenging time working with the surrounding noise around them than others. And sometimes, it’s just good to get away from people, voices, and sounds. If there is no meeting taking place at a conference room, this can be a short-term solution to offer a quiet place to employees. A separated space dedicated to work in peace and quiet is an even better solution and works long term. Provide rooms that allow individuals to focus appropriately on their work. Ideally they should be soundproof and comfortable to spend there even few hours.
4. Soundproof Pods for Quick Meetings, Chats & Individual Work
One of the best soundproof solutions are acoustic pods. Depending on your needs, you can choose pods of different sizes. For individual work, choose Space M, for more collective tasks or small meetings consider Space L or Space XL. Talk to your teams, ask them what they need. Locate the pods wisely and strategically, so teams have easy access right next to their office area. Additionally, you can encourage every employee to use the pods frequently. That way, conversations are kept private, and other team members are not getting distracted and disturbed. Place whiteboards inside a pod for meetings, use innovative whiteboard paint surfaces on the outside of the pod to scribble invitations to use the pod on it. If you need to make changes to increase the use and make the most of it, you can constantly adjust and relocate them.
5. Clever Office Design
We all know the familiar clacking of high heels on tiled and stone floors. It's a sound that can be heard throughout the office. But with the right flooring, you can put an end to sound and loud noises. In the past, many interior decorators used to use carpets. But let's face it: when the coffee falls off the desk, the colleague is forever immortalised on the office floor. The care and cleaning of carpets are too time-consuming. Parquet and LVT floors offer an easy-care and versatile alternative.
A loud environment also increases the stress level of many employees
The health and well-being of office workers influence their productivity - this has been the subject of much research. Staff costs, including salaries and benefits, make up a large part of a company's operating costs. So anything that improves productivity also has a positive financial impact on an employer.
At the same time, most employees work in open-plan offices, which are not very popular, to say at least. 76 % of respondents said that they "hate" open offices. A loud environment also increases the stress level of many employees. As a result, many employees either quit their job or have a burn-out.
Common noises that decrease the well-being of teams
People can only tolerate noise for a certain amount of time before it becomes annoying and bothers them. Many workers work without realizing that noise in the office is affecting their productivity. Some sources of noise are:
→ Excessive background noise from mechanical and technical operations in the office, such as air conditioners, fans, printers, copiers, and even just typing on the keyboard.
→ Loud conversations, laughter, and the ringing of telephones.
→ Activity noises which are caused by loud footsteps, chat notifications, swearing because the PC doesn't want to do what the employee wants it to do.
→ Outside noises such as road traffic, sirens, trains, and planes. Of course, a certain amount of external noise is completely normal. But too much noise can interfere with concentration and productivity.
→ Use of speakers during a phone call.
When you reduce noise levels, you create a more pleasant environment for employees and customers alike.
4 Benefits of Acoustic Solutions
With all this noise around you, you need to find ways to reduce it to be able to work and deliver convincing results. Acoustic solutions can do a lot for you in the office. We will show you how to reach your acoustic goals.
1. You reduce stress and improve well-being
Open Office noise is one of the most critical factors that stress people at work. A constant information overload, non-stop noise, distractions – all of those points are highly stressful for employees. Moreover, it affects our productivity, stressing us even more. And if the stress is terrible on a day in the office, it can sometimes lead to quarrels and tensions between colleagues.
65% of 1000 UK-based office workers reported in a survey that noise in their workplace significantly impacted their ability to work in an accurate and timely manner. 44 % even stated that the noise affected their overall well-being. 40 % of them felt stressed due to those circumstances.
Noisy environments are one of the biggest complaints about workplaces. A lot of background noise increases stress by interfering with general hearing and concentration. When you reduce noise levels, you create a more pleasant environment for employees and customers alike. By placing some sound-attenuating walls and separators between desks, you can lower the level of noise. You can reach an even higher sound absorption in rooms and open space offices by using acoustic lamps, panels, or prints on the walls. And if you need absolute silence: Soundproof pods can be acoustic shelters. Use them any time you want to escape constant noise and distractions.
2. You provide privacy
A lack of privacy can be stressful, too. In an open space office, everyone sees how we work and what we are doing right at that moment. Hearing our colleagues’ conversations makes us less productive, tires us, and affects our mood. It's in our nature to feel comfortable only when we have some basic level of privacy. That's why the privacy issue is the biggest issue of open spaces. According to a survey performed in 2018 in the USA, almost 48% of respondents point it out as a significant problem.
Ease of communication is one of the main benefits of an open-plan office. Yet, it is sometimes necessary for staff to have private conversations. Acoustic panels or pods muffle sound and allow employees to have conversations without being overheard.
With acoustic screens like Wall, you can separate space, keep teams together and absorb the noise around them and their noise just as much, so they don't disturb other teams around them. Pods will provide solutions with even more options. Move away from everyone to have a quick phone call in Space S or have an effective 1-on-1 in one of our bigger pods.
3. You improve productivity
Plenty of researches show that the easiest way to stay productive is to get rid of distractions and focused only on one thing at a time. However, it isn't easy:
→ 52 % of respondents say they're distracted 1-20 per cent of the time during a workday
→ 43 % say they're distracted 21-75+ percent of the time
→ 5% say they're never distracted
Lower productivity is often associated with high noise levels because of the increased risk of distractions. Improving acoustics makes it easier for employees to concentrate, make and receive calls, and hold conversations at a comfortable volume without distracting other colleagues.
Using our soundproof pod Space M will fight all distractions. It creates spaces for individual-focused work – Quiet Zones. Also, it has been proven that even a simple change of surroundings could be a good thing to boost your creativity. That's why you should provide a variety of spaces for your employees.
4. You improve the soundscape and facilitate communication.
Acoustic solutions absorb unwanted sounds such as echoes and noise from the environment and make other sounds clearer. As a result, people in open-plan offices, restaurants, or hotel lobbies can hear and understand each other better.
A 2018 Harvard Business School study found that open-plan offices lead to a 70% decrease in face-to-face communication (Bernstein & Turban, 2018). That's because even if we talk to each other in an open space, we are not facing each other. Therefore, open office conversations are often "too casual", shallow and quick. Open office is maybe great for convenient chat, but there is a lot more to talk about at work. More serious, deeper conversations require a level of privacy that only a quiet environment can give you. That way, you can have eye-to-eye conversation without any distractions because the laptop battery is empty or the connection is low.
In that case, you need more than acoustic screens like our Wall or Cone , but a pod that provides enough space for meetings and small conferences. Using Space L or Space XL will provide quiet surroundings in an open space office. Plus, with the constant air flow you won't risk a headache and tiredness.
When you’re creating something new, it’s good to ask yourself if you are adding something interesting to the surroundings without taking too much from the environment.
– Maja Ganszyniec
Meet the figure behind our Mist family, a virtuoso of product and furniture design - Maja Ganszyniec from Studio Ganszyniec. Maja is a designer with a comprehensive approach to the design process, graduated from Design Product at Royal College of Art and Interior Architecture on Cracow Academy of Fine Arts.
Over the last ten years she has been working across Europe on projects for leading brands such as: IKEA, Leroy Merlin, Amica, Mothercare, Orange, Dupont, Camper, Comforty, PayPass, Touchideas and Bellamy. Her works had been shown on recognised exhibitions in Milan, Amsterdam, Berlin, London, and published by Domus, Icon, Abitare and Wallpaper Magazines.
Mute: The past years have been busy for you. You’ve been working on few collections for IKEA, developing your own brand and delivering projects for your long-term clients. What was the most interesting and inspiring aspect of creating Mist lamps? How do they complete your work?
Maja Ganszyniec: It’s my first project that combines two very interesting sides – acoustics and light. Until now my projects mainly focused on more classical interior design elements. However, the concept of acoustic comfort was always very close and personal to me, because noise reduction becomes a more and more challenging issue, mostly in open space offices.
M: Do you have a theory why?
MG: Partly because open space concept became so popular and has been implemented almost in every bigger office. The general idea of open plan office, developed in 50s in Germany, was meant to foster communication within the company. But lately it went the other way around. Several studies discovered that open office plan decreases number of face-to-face interactions between employees. Plenty of workers sit in a headphones or in conference rooms. It’s simply because open offices are full of noise and people observe on a daily basis that it has a negative impact on their work. On top of that people’s work is becoming more complicated, requiring more time for a focused work. Recently I’ve observed many new solutions for noise reduction in business spaces and I’m happy to add something innovative to this emerging trend.
M: So why did you find designing the acoustic lighting an interesting project if there are so many solutions already on the market?
MG: In my opinion, they are effective, yet very similar to each other. From an aesthetic point of view, they often lack of something unique that could make them an acoustic tool and also a piece of decoration. To me, it was a chance to create one of the first decorative acoustic products that could look great in modern-designed offices, in fancy restaurants, or a glamorous hotel.
M: So, the goal was to create something unique but also practical and useful?
MG: I believe that in modern interior design, every inch and square meter has to be used effectively. I’ve observed that in some offices plenty of space is taken by acoustic products with only one function. In my opinion, the era of one-function products is coming to an end as we have less and less space, and we’ve got to make the most of it. That is why the Mist Lamp is multifunctional: sound absorber, space divider, and lamp.
M: Only three functions, nothing more? :)
MG: On top of it, there is an inductive charger or USB A+C port on the surface of every Mist lamp, so we can call it a device charger as well.
M: What’s behind all these functions? What was your big idea?
MG: I wanted to create something that could be a practical space divider but with some subtlety to it. That’s why the context of light is so important. Most of these kinds of products are just walls. I’ve observed that every traditional space divider makes a place a little bit darker and more gloomy. I chose a delicately transparent fabric because I wanted to allow the light to shine through and penetrate the room. During the day, semi-transparent curtains ensure the lamp’s translucency, letting in the sun. After dark, a pleated curtain ensures a comforting, understated light that works beautifully in every surrounding, creating a comfortable atmosphere. On top of that, thanks to the fabric we’ve used, MIST creates a magical visual effect – when you turn on the light, it seems like the top cover of the lamp is floating gently in the air.
M: What was the main technical challenge with creating the product?
MG: The hardest part was to find a proper solution to make it look soft and transparent and, at the same time to obtain a high level of blocking and sound-absorbing quality. With cooperation with Mute’s product technologists, we’ve done that using invisible wall made of plexiglass that also creates acoustic cavities on both sides of the product. Part of the soundwaves are “caught inside,” and because of that, the lamp limits reverberation.
MG: Finally, what are the key features of well-designed products, in your opinion?
M: Lovability :) Shape, function, ease of use. And, of course, sustainability. When you think about it, the world doesn’t necessarily need more chairs or lamps. So, when you are creating something new, it’s good to ask yourself if you are adding something interesting to the surroundings without taking too much from the environment. I am glad that Mute looks at that issue the same way.
Tired eyes, a cracked psyche, mood swings, headaches - these can all be effects of the wrong lighting.
The lighting of a room influences us in our work and concentration and has a decisive effect on our productivity and well-being. Tired eyes and headaches can be consequences of wrong lighting in a room.
The right light, therefore, has a big impact on a pleasant working atmosphere. So while designing an office, thinking beyond desks and technical equipment is required. We will tell you how companies and organizations can ensure the right light environment in their offices.
The Effect of Daylight and the Right Desk Set-up on Our Health
There is no denying that daylight is important to our productivity and the efficiency of our work. But it's not just professionally crucial to work in the right setting - our health will thank us for it too. Tired eyes, a cracked psyche, mood swings, headaches - these can all be effects of the wrong lighting. As Philips makes clear in a report, sunlight and natural light, in particular, have an impact on our well-being and work performance. To support employees in their work, companies need to create a pleasant lighting atmosphere in the office.
Bell with GOLF LED creates warm ambient lighting
Line with double LEDs emits bright beam
Different Types of Lighting to Create a Perfect Environment
Different types of lightning can support employees in the way they work and help companies to provide an atmosphere that will contribute to their well-being at the workplace.
Task Lighting vs. Ambient Lighting
Ambient lighting is the general lighting of a room. It substitutes as natural light and provides the overall illumination of a room. Chandeliers, ceiling lights, and even wall lights that lighten up more than on spot create an even lighting level and a relaxing environment in offices and public areas like restaurants, receptions and hotel lobbies.
The use of task lighting is already included in its name as it is light at a specific spot that is used to be able to do certain tasks like writing or reading. This type of light helps to stimulate our brain and supports us when we have to concentrate and focus. Therefore, light sources like pendant lamps above desk areas, desk lamps and swing arm lamps, fall under the category of task lighting. They are great solutions for work stations, conference rooms and open-plan offices.
While designing spaces, companies need to ensure the necessary illumination levels for each possible area. To do so, they have to consider "Lux" and "Lumens". Lumen is the total amount of light emitted in all directions from the source. Lux is a measure of illuminance - a total amount of light that falls on a Surface. The same lamp will deliver different amounts of luxes depending on how high it is hung. At the same time different areas require different numbers of luxes. Workstations and meeting rooms need to ensure 500 lux, and reception desks need 300 lux. Entrance halls, on the other hand, only need 100 lux.
Light Colour 3K or 4K
LED lamps and luminaires are available in several colour temperatures. Lamp colour is often a personal choice that is made depending on the environment that should be created. However, most common in office and public spaces are 3000k and 4000k lights. 4000k is a cooler and whiter light that helps to keep people focused. It is mainly used for task lighting. 3000k light, on the other hand, brings a warmer light to a room but may make people a little sleepy after working in this light for a few hours.
Added Options For an Even Better Light Set-up
Additional functions of lightning can provide even more comfort. Very bright light can be dimmed thanks to a Dali dimmer. That way, you can enjoy a little break or adjust the light according to the room and the setting. The microprism diffuser provides a high level of visual comfort. It is ideal for lighting workplaces with its special prismatic structure, as it has low glare due to its special design. With it you can ensure perfect lighting conditions, especially in the workplace.
The right lighting is essential in modern offices. Therefore, you should focus on designing an environment that supports creativity and productivity and increases everyone's well-being. The right lighting solutions not only bring comfort and a pleasant atmosphere but are also flexible and smart and can be adjusted to individual needs easily.
We have to embrace change, take employees' needs seriously, and work with them to grow the company.
2020 has been a year of obstacles to overcome for many companies. 2021 is seen as a year of change and renewals.
A rethinking of the way we work and the design of workspaces was necessary. Now a new normal has to be applied in many office spaces.
Working as a Team in a Redesigned Office
Despite the advantages of working from home, most employees hope to return to the office after the pandemic or at least find part-time remote solutions that let them work in the office and from home. Many miss the contact with their co-workers, especially since social connections build trust and bonds in teams.
Digitalization became even more important, and many organizations developed great solutions to connect teams. Socialising cannot happen from the home office or through video calls only, and the office experience finds new value.
During the lockdown, companies had to find ways to have a proper workflow and processes while working remotely. For many, this led to an optimisation of work processes that can easily be adapted to the office's work. This also means that offices need to be redesigned in order to provide the right working spaces for team meetings, collaborations, and efficient working in privacy.
Three Advantages of a New Office
The design of a new office is connected to many advantages you will have as a company and especially for your employees to work effectively without being stressed and being under mental pressure.
1. More Privacy
Working in a large office space often takes away privacy and the possibility to work in peace. Many employees struggle with productivity and efficiency in shared areas. But new offices in 2021 will be different. With the right steps and measures, companies will be able to create privacy and develop a sense of psychological comfort and security. Ideas can spread when people feel at ease. Privacy screens or a further distance to colleagues help with the acoustics around you, and protect you from noises in adjacent workspaces. Solutions like acoustic pods will give you the ability to focus on your work and hold uninterrupted meetings.
Space XL for the biggest brainstorms
Space L Meeting for a project meetup
2. Less Working Stations More Co-working
New offices will provide more than just some desks, chairs and the usual office environment. They will be collaboration spaces. As per Workspace Utlization Index by Density 76% of the time meeting rooms are occupied by maximum 4 people and 86% of the time by maximum 6 people. This is why companies will more often choose pods instead of building conference rooms. Teams need a place to work on a large scale and complex projects without sending mails around to communicate. Sitting together they will be able to move forward with their project way faster and more efficient.
The JLL’s Global findings on workplace re-entry during COVID-19 research has shown that organizations have been increasingly allocating less square footage to individual desks. It’s clear that safely re-entering the workplace will require a reversal of that densification trend, at least for the near-term.
Space L Double for long project sessions
Space M Double for quick one-to-ones
3. Flexibility and Mobility
Future work spaces require more flexibility. Furniture and acoustic solutions you choose need to be easy to adjust to individual requirements and situations. The number of people using it may vary, so agile solutions are needed. With our pods you can change the setup and the purpose or move them around to easily rearrange office according to your needs.
Wall on coasters with whiteboard stimulates the creativity
Agility and Flexibility for a Better Work Environment
Adaptability, agility, and flexibility define the office spaces of the future. We have to embrace change, take employees' needs seriously, and work with them to grow the company. In 2020 companies were in a short period of hibernation. This year many are working full speed on new solutions to adapt to the new needs of employees and a work environment that is important for our mental and physical health.
Moisture can slowly penetrate materials and permanently damage them. At Mute, we are committed to our products' longevity and therefore started using the vapor control layer in all our pods on January 1st, 2021. This layer stops moisture from flowing between zones inside the pod walls.
The vapor barrier layer sits between the outer wall and the inner wall that is filled with a proprietary composition of sound isolating and absorbing materials. Thus, the vapor barrier layer performs the function of moisture regulation inside the wall.
→ Moisture from the outside cannot penetrate during transportation and use.
→ Fungus and mold growth inside the walls are prevented. This increases the safety of use.
The robust and flexible vapor control layer produce a reliable permanent internal barrier in our pods' walls and help create a pleasant environment and guarantee the longevity of our products.
Thanks to the vapor barrier, we can create a healthy environment in offices and for your employees.