M E D I C I ACOUSTIC SOLUTIONS
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Definition of sound
Sound consists of pressure waves running through the air. It can be described as energy, created by vibrations, transmitted through air or any other medium. The inner ear converts those vibrations into electric signals, which are sent to our brain, where they will be processed and perceived as the actual sound coming in.
These sound waves have two different characteristics:
Frequency (Hz) determines the tone of the sound
Decibel (dB) determines the intensity of sound
Frequency: how sound waves travel
The wavelength determines the sound frequency. It is measured as the number of repetitive vibrations per cycle per second and is expressed in Hertz (Hz).
The audible range of sound is between 20 to 20 000 Hz. The higher the frequency, the higher the tone. However, for space planning, the suggested frequency ranges from 100 to 5000 Hz.
High tones
High frequency | Short wave | 2 500 - 12 000 Hz | e.g. cellphone ring tones
Mid tones
Speech frequency | Mid length wave | 250 - 2500 Hz | e.g. speech
Low tones
Low frequency | Long wave | 50 - 250 Hz | e.g. Heating, ventilation and air conditioning
Decibel (dB): the intensity of sound
Decibel (dB) is a logarithmic unit to express the ratio of sound intensity (volume) and is important as an indicator of the background noise level. Humans can hear sounds between 0 and 140 decibels. The value of decibels has no direct or indirect correlation with the sound frequency.
For example, the ticking of a clock and the buzzing of a vacuum cleaner may have the same frequency but a different volume.
Why it matters? In today’s open-plan workspaces, employees are exposed to noise pollution. The level of noise ranges from 60 to 80 decibels, whereas recommended background noise level in an office is around 45 dB.
Noisy offices above the suggested threshold may hamper:
concentration
interfere collaboration
But there is always a way to avoid getting stressed by trying to keep focus at work. The solution could be several workplace micro-environments, designed with sound balance in mind for the activity and the people using these areas.
How loudly different sounds are perceived:
10 dB – Breathing, 20 dB – Mosquito, 30 dB – Whispering, 40 dB - Fridge, 60 dB - Conversation, 70 dB - Vacuum Cleaner,
80 dB - Truck, 90 dB - Lawnmower, 100 dB - Helicopter, 110 dB - Rock concert, 120 dB – Police siren, 130 dB - Jet plane,
160 dB - Pistol shot
Reverberation time: the time for a sound to drop dead
Reverberation time is the time needed for an original sound source to decay to 60dB and is expressed in seconds. In order to generate excellent speech intelligibility and clarity, the reverberation time should be adjusted and balanced by means of absorptive material in function of the specific acoustical issues in a given space. The reverberation time will always be influenced by
the volume of the room,
room temperature, and
existing absorptive materials in the room, e.g. materials, objects, and people.
Recommended reverberation time for different spaces:
Office: 0.75s
Meeting room: 0.60s
Cafeteria: 1.00s
Gymnasium: 1.50s
Auditorium: 1.50 to 2.00s
By measuring the reverberation time in your space allows M E D I C I to improve your room acoustics by adding sound absorbing and soundproofing materials.
Why it matters? In an office, high reverberation intensifies the existing distracting sounds, as the sound reflects from walls and tables, among other hard surfaces. For instance, reverberation may cause:
Difficulties to understand your conversations with colleagues
Distractions due to people speaking at the other end of large spaces
Reverberation and echo
There is reverberation in every room. This means that the sound is reflected, thereby hanging around in the room. To find out if a room has long or short reverberation, you can test it with a regular hand clap. The sooner you hear the sound, the shorter the reverberation of the room, which is good.
Echo is basically the same phenomenon as reverberation. It also occurs when sound is reflected by a surface, but it’s experienced the second time with such a long delay that it becomes like a separate sound. A delay of one tenth of a second is usually required for it to be perceived as an echo, which means that the reflecting surface usually needs to be at least 17 meters away. But faster echoes can occur if the sound bounces several times between two surfaces at shorter distances. This is called flutter echo and can be experienced in underpasses and the like. The echo also becomes stronger if the reflective surface is arched.
Building acoustics vs. Room acoustics
Building acoustics
Building acoustics and room acoustics may sound like two sides of the same coin, but don’t be fooled. We have to make a clear distinction, as the solutions to treating problems associated with either of the two are very different. As the name implies, building acoustics has to do with the building and the transmission of sound from outdoor to indoor and between structural elements of a building, e.g. floors and walls.
This is the case when:
Sound is transferred from outdoor to indoor, e.g. cars, trams, airplanes passing by
Sound is transferred between floors, e.g. footsteps from the floors above
Sound is transferred between adjacent rooms, e.g. an adjacent meeting room
Ideally, issues like these should be addressed through the insulation of windows, walls, ceilings, and floors. Another option is to remedy the transmission of sounds, so they will not escape the room, to begin with.
Room acoustics
Room acoustics, pertain to noise and sounds within a room or any given space. Rather than focusing on insulation to remedying transmission of sounds, the key to room acoustics is absorption to prevent sound waves from bouncing back-and-forth in a room.
Principles for good acoustics
To create a better acoustical environment and reduce reverberation time in a room, M E D I C I acoustic solutions are developed to perform on one or more of the following acoustic principles.
1. Absorption
Sound Waves are absorbed by any acoustically soft material they encounter.
Sound is energy, and in order to stop this energy from propagating, absorptive panels must be used to convert this energy into heat through friction. The absorption coefficient of a product will determine the level and quality of absorption. Absorption solutions can be applied to cavity of drywall, floor, fixed wall or ceiling elements, e.g.
2. Attenuation/Sound Dampening
Reducing the sound transfer within a room.
In order to reduce the sound transfer between different spaces, vertical elements will be applied to cut down sound energy, either pending from the ceiling or free-standing.
Never underestimate how attenuation or sound dampening has a positive impact on speech intelligibility and clarity. It’s no wonder that a positive acoustic experience that absorbs disturbing sounds leads to a quieter place, fosters focus and inspires effective collaboration within an energetic workspace.
3. Diffusion
Sound energy is spread evenly in a given space.
Wavelengths, which can’t be absorbed through acoustic treatment, will dissipate evenly back into the room, ensuring a better spread while maintaining a live, vivid sound. Otherwise, the sound will be reflected back in a linear way, resulting in a remaining unpleasant sound. This property can be obtained by alternating different depths of absorptive material and 3D shapes.
4. Soundproofing / Sound Blocking
Mass density vinyl (MLV) is a reliable choice for soundproofing materials. High density mass loaded vinyl is a thick barrier material that can block all annoying sounds. More importantly, it will reduce the transmission of sound without shrinking your living space. When performing noise reduction processing, you must understand all the advantages and disadvantages of different materials. For example, if you need soundproof walls, floors or ceilings, you need to know whether the material is suitable.
When you want to soundproof your home or office space, the best option is to add weight. Even for amateurs, this sounds logical. High density mass loaded vinyl is like that. However, it is also very flexible. This means that it is not difficult to install it on the floor, wall and ceiling.
Textiles are the perfect material for complementing other acoustic solutions. Especially curtains that are developed for sound absorption. Compared to other sound absorbers, they are more cost effective, flexible, and stylish too. They also perform the same functions as regular curtains. They become a part of your interior design which can screen off areas, regulate light, and create spaces in the room.
Like other sound absorbers, acoustic textiles are most effective against relatively high-frequency tones. In a workplace, for example, it could be about ventilation systems, electrical buzzing sounds, not forgetting disturbing chatter. Since conversations and especially mobile calls are some of the most disturbing things that can happen in the workplace. Our brains are programmed to find and understand a common thread. Given that we usually only hear one person on a mobile call, this makes it difficult to concentrate on anything else.
How you hang the textiles is important
When we test our acoustic textiles, we hang them at both 10 and 15 cm away from the wall. It’s around this point that they absorb the most sound. So hang them 10-15 cm from the wall if you want as much sound reduction as possible from your acoustic curtain. In addition, the curtain muffles more noise if there are more folds in it. Also, keep in mind that the sound bounces between parallel surfaces, i.e. between walls or the floor and ceiling. So it makes a big difference even if only one of the surfaces has a sound absorber. And remember that a curtain can be used in more places than just in front of a window. For example, it could hide a dull plaster wall with poor acoustic properties, or be used as a flexible wall to create space in the room.
Reasons to choose acoustic curtains
+ Cost-effective
+ Multi-functional
+ Becomes a part of the decor rather than a necessary evil
+ Easy to place (or move)
+ Doesn’t need expensive installation
+ Effective in high-frequency areas
+ Covers large spaces and thereby absorbs a lot of sound
+ Flexible as they can be drawn together or apart
Why good acoustics are important
Good air, good light, and good ergonomics have long been standard features of workplaces, and rightly so. But good sound conditions are also important, because noise can affect us in a very negative way. It can damage our hearing even at low noise levels if it continues for a long time. And even if the noise pollution isn’t directly damaging, it can affect us indirectly in many ways. A noisy environment with long reverberation causes unnecessary stress, which in turn can lead to both physical and mental problems. Noise makes it more difficult to have a normal conversation. It makes us raise our voices, which leads to higher noise levels. Noise also affects our attention. We have a harder time concentrating, which negatively affects the work we do.
Studies show that long reverberation is the single largest factor leading to discontent and poorer health. The survey focused on teachers and shows that people who work in rooms with a long reverberation are six times more likely to look for a new job. They are less motivated and more fatigued. In addition, they experience the climate in classrooms as less relaxed and more aggressive.
With sound-absorbing textiles you reduce reverberation, which means the brain doesn’t need to process as many irritating noises that have no informative value. This gives us a greater capacity for remembering, solving problems, and managing useful information. In other words, good acoustics are a good investment - both in terms of health and from a purely business perspective.
A product's ability to absorb sound determines its sound absorption coefficient. This could be anywhere from 0.0 which means non-existent absorption to 1.0 which is total absorption. The result itself is called the alpha value and is abbreviated to ‘a’. If it says ‘ap’ it means ‘practical alpha’ which means it’s linked to a specific frequency while ‘aw’ means ‘weighted alpha’ which means independent of frequency. The alpha value in turn determines which absorption class a product belongs to. If the product has aw 0.9, it absorbs 90% of the sound and belongs to class A. If the alpha value is below 0.15, it absorbs too little to be sound absorbing-classed at all.
ABSORPTION CLASSIFICATIONS: CLASS A = 90-100%, CLASS B = 80-85%, CLASS C = 60-75%, CLASS D = 30-55%
M E D I C I ACOUSTIC SOLUTIONS (Click on any item below (in red) to visit individual web page)
Sound consists of pressure waves running through the air. It can be described as energy, created by vibrations, transmitted through air or any other medium. The inner ear converts those vibrations into electric signals, which are sent to our brain, where they will be processed and perceived as the actual sound coming in.
These sound waves have two different characteristics:
Frequency (Hz) determines the tone of the sound
Decibel (dB) determines the intensity of sound
Frequency: how sound waves travel
The wavelength determines the sound frequency. It is measured as the number of repetitive vibrations per cycle per second and is expressed in Hertz (Hz).
The audible range of sound is between 20 to 20 000 Hz. The higher the frequency, the higher the tone. However, for space planning, the suggested frequency ranges from 100 to 5000 Hz.
High tones
High frequency | Short wave | 2 500 - 12 000 Hz | e.g. cellphone ring tones
Mid tones
Speech frequency | Mid length wave | 250 - 2500 Hz | e.g. speech
Low tones
Low frequency | Long wave | 50 - 250 Hz | e.g. Heating, ventilation and air conditioning
Decibel (dB): the intensity of sound
Decibel (dB) is a logarithmic unit to express the ratio of sound intensity (volume) and is important as an indicator of the background noise level. Humans can hear sounds between 0 and 140 decibels. The value of decibels has no direct or indirect correlation with the sound frequency.
For example, the ticking of a clock and the buzzing of a vacuum cleaner may have the same frequency but a different volume.
Why it matters? In today’s open-plan workspaces, employees are exposed to noise pollution. The level of noise ranges from 60 to 80 decibels, whereas recommended background noise level in an office is around 45 dB.
Noisy offices above the suggested threshold may hamper:
concentration
interfere collaboration
But there is always a way to avoid getting stressed by trying to keep focus at work. The solution could be several workplace micro-environments, designed with sound balance in mind for the activity and the people using these areas.
How loudly different sounds are perceived:
10 dB – Breathing, 20 dB – Mosquito, 30 dB – Whispering, 40 dB - Fridge, 60 dB - Conversation, 70 dB - Vacuum Cleaner,
80 dB - Truck, 90 dB - Lawnmower, 100 dB - Helicopter, 110 dB - Rock concert, 120 dB – Police siren, 130 dB - Jet plane,
160 dB - Pistol shot
Reverberation time: the time for a sound to drop dead
Reverberation time is the time needed for an original sound source to decay to 60dB and is expressed in seconds. In order to generate excellent speech intelligibility and clarity, the reverberation time should be adjusted and balanced by means of absorptive material in function of the specific acoustical issues in a given space. The reverberation time will always be influenced by
the volume of the room,
room temperature, and
existing absorptive materials in the room, e.g. materials, objects, and people.
Recommended reverberation time for different spaces:
Office: 0.75s
Meeting room: 0.60s
Cafeteria: 1.00s
Gymnasium: 1.50s
Auditorium: 1.50 to 2.00s
By measuring the reverberation time in your space allows M E D I C I to improve your room acoustics by adding sound absorbing and soundproofing materials.
Why it matters? In an office, high reverberation intensifies the existing distracting sounds, as the sound reflects from walls and tables, among other hard surfaces. For instance, reverberation may cause:
Difficulties to understand your conversations with colleagues
Distractions due to people speaking at the other end of large spaces
Reverberation and echo
There is reverberation in every room. This means that the sound is reflected, thereby hanging around in the room. To find out if a room has long or short reverberation, you can test it with a regular hand clap. The sooner you hear the sound, the shorter the reverberation of the room, which is good.
Echo is basically the same phenomenon as reverberation. It also occurs when sound is reflected by a surface, but it’s experienced the second time with such a long delay that it becomes like a separate sound. A delay of one tenth of a second is usually required for it to be perceived as an echo, which means that the reflecting surface usually needs to be at least 17 meters away. But faster echoes can occur if the sound bounces several times between two surfaces at shorter distances. This is called flutter echo and can be experienced in underpasses and the like. The echo also becomes stronger if the reflective surface is arched.
Building acoustics vs. Room acoustics
Building acoustics
Building acoustics and room acoustics may sound like two sides of the same coin, but don’t be fooled. We have to make a clear distinction, as the solutions to treating problems associated with either of the two are very different. As the name implies, building acoustics has to do with the building and the transmission of sound from outdoor to indoor and between structural elements of a building, e.g. floors and walls.
This is the case when:
Sound is transferred from outdoor to indoor, e.g. cars, trams, airplanes passing by
Sound is transferred between floors, e.g. footsteps from the floors above
Sound is transferred between adjacent rooms, e.g. an adjacent meeting room
Ideally, issues like these should be addressed through the insulation of windows, walls, ceilings, and floors. Another option is to remedy the transmission of sounds, so they will not escape the room, to begin with.
Room acoustics
Room acoustics, pertain to noise and sounds within a room or any given space. Rather than focusing on insulation to remedying transmission of sounds, the key to room acoustics is absorption to prevent sound waves from bouncing back-and-forth in a room.
Principles for good acoustics
To create a better acoustical environment and reduce reverberation time in a room, M E D I C I acoustic solutions are developed to perform on one or more of the following acoustic principles.
1. Absorption
Sound Waves are absorbed by any acoustically soft material they encounter.
Sound is energy, and in order to stop this energy from propagating, absorptive panels must be used to convert this energy into heat through friction. The absorption coefficient of a product will determine the level and quality of absorption. Absorption solutions can be applied to cavity of drywall, floor, fixed wall or ceiling elements, e.g.
2. Attenuation/Sound Dampening
Reducing the sound transfer within a room.
In order to reduce the sound transfer between different spaces, vertical elements will be applied to cut down sound energy, either pending from the ceiling or free-standing.
Never underestimate how attenuation or sound dampening has a positive impact on speech intelligibility and clarity. It’s no wonder that a positive acoustic experience that absorbs disturbing sounds leads to a quieter place, fosters focus and inspires effective collaboration within an energetic workspace.
3. Diffusion
Sound energy is spread evenly in a given space.
Wavelengths, which can’t be absorbed through acoustic treatment, will dissipate evenly back into the room, ensuring a better spread while maintaining a live, vivid sound. Otherwise, the sound will be reflected back in a linear way, resulting in a remaining unpleasant sound. This property can be obtained by alternating different depths of absorptive material and 3D shapes.
4. Soundproofing / Sound Blocking
Mass density vinyl (MLV) is a reliable choice for soundproofing materials. High density mass loaded vinyl is a thick barrier material that can block all annoying sounds. More importantly, it will reduce the transmission of sound without shrinking your living space. When performing noise reduction processing, you must understand all the advantages and disadvantages of different materials. For example, if you need soundproof walls, floors or ceilings, you need to know whether the material is suitable.
When you want to soundproof your home or office space, the best option is to add weight. Even for amateurs, this sounds logical. High density mass loaded vinyl is like that. However, it is also very flexible. This means that it is not difficult to install it on the floor, wall and ceiling.
Textiles are the perfect material for complementing other acoustic solutions. Especially curtains that are developed for sound absorption. Compared to other sound absorbers, they are more cost effective, flexible, and stylish too. They also perform the same functions as regular curtains. They become a part of your interior design which can screen off areas, regulate light, and create spaces in the room.
Like other sound absorbers, acoustic textiles are most effective against relatively high-frequency tones. In a workplace, for example, it could be about ventilation systems, electrical buzzing sounds, not forgetting disturbing chatter. Since conversations and especially mobile calls are some of the most disturbing things that can happen in the workplace. Our brains are programmed to find and understand a common thread. Given that we usually only hear one person on a mobile call, this makes it difficult to concentrate on anything else.
How you hang the textiles is important
When we test our acoustic textiles, we hang them at both 10 and 15 cm away from the wall. It’s around this point that they absorb the most sound. So hang them 10-15 cm from the wall if you want as much sound reduction as possible from your acoustic curtain. In addition, the curtain muffles more noise if there are more folds in it. Also, keep in mind that the sound bounces between parallel surfaces, i.e. between walls or the floor and ceiling. So it makes a big difference even if only one of the surfaces has a sound absorber. And remember that a curtain can be used in more places than just in front of a window. For example, it could hide a dull plaster wall with poor acoustic properties, or be used as a flexible wall to create space in the room.
Reasons to choose acoustic curtains
+ Cost-effective
+ Multi-functional
+ Becomes a part of the decor rather than a necessary evil
+ Easy to place (or move)
+ Doesn’t need expensive installation
+ Effective in high-frequency areas
+ Covers large spaces and thereby absorbs a lot of sound
+ Flexible as they can be drawn together or apart
Why good acoustics are important
Good air, good light, and good ergonomics have long been standard features of workplaces, and rightly so. But good sound conditions are also important, because noise can affect us in a very negative way. It can damage our hearing even at low noise levels if it continues for a long time. And even if the noise pollution isn’t directly damaging, it can affect us indirectly in many ways. A noisy environment with long reverberation causes unnecessary stress, which in turn can lead to both physical and mental problems. Noise makes it more difficult to have a normal conversation. It makes us raise our voices, which leads to higher noise levels. Noise also affects our attention. We have a harder time concentrating, which negatively affects the work we do.
Studies show that long reverberation is the single largest factor leading to discontent and poorer health. The survey focused on teachers and shows that people who work in rooms with a long reverberation are six times more likely to look for a new job. They are less motivated and more fatigued. In addition, they experience the climate in classrooms as less relaxed and more aggressive.
With sound-absorbing textiles you reduce reverberation, which means the brain doesn’t need to process as many irritating noises that have no informative value. This gives us a greater capacity for remembering, solving problems, and managing useful information. In other words, good acoustics are a good investment - both in terms of health and from a purely business perspective.
A product's ability to absorb sound determines its sound absorption coefficient. This could be anywhere from 0.0 which means non-existent absorption to 1.0 which is total absorption. The result itself is called the alpha value and is abbreviated to ‘a’. If it says ‘ap’ it means ‘practical alpha’ which means it’s linked to a specific frequency while ‘aw’ means ‘weighted alpha’ which means independent of frequency. The alpha value in turn determines which absorption class a product belongs to. If the product has aw 0.9, it absorbs 90% of the sound and belongs to class A. If the alpha value is below 0.15, it absorbs too little to be sound absorbing-classed at all.
ABSORPTION CLASSIFICATIONS: CLASS A = 90-100%, CLASS B = 80-85%, CLASS C = 60-75%, CLASS D = 30-55%
M E D I C I ACOUSTIC SOLUTIONS (Click on any item below (in red) to visit individual web page)
- SENSE: Class A 0.90 (90%) Sound Absorbing use: curtains or to upholster acoustic wall panels
- AKEMI: Class B 0.80 (80%) Sound Absorbing use: curtains or to upholster acoustic wall panels
- TWIN: Class B 0.85 (85%) Sound Absorbing use: dim-out curtains
- BRISA : Class A 1.0 (100%) Sound Absorbing use: upholstery and to upholster acoustic wall panels
- APHONFLEX : Class C 0.60 (60%) Sound Absorbing use: Vinyl Wall-Covering
- SONAR : Class D 0.40 (40%) Sound Absorbing use: Vinyl Wall-Covering
- CORK PANELS: Class C 0.60 (60%) Sound Absorbing & Sound Diffuser use: wall-covering, ceiling
- WOOL - FELT: Class A 0.95 (95%) Sound Absorbing use: walls, ceilings, upholstery, lighting.
- MINERAL GLASS WOOL: Class B 0.83 (83%) Sound Absorbing use: drywall cavity fill, ceiling insulation, floor insulation
- MLV FLEXIBLE NOISE BARRIER use: soundproofing for drywalls
- PET ACOUSTIC FELT 9mm : Class D 0.30 (30%) | 12mm : Class D 0.45 (45%) | 24mm : Class C 0.60 (60%) Sound Absorbing
- PET ACOUSTIC PLAIN PANELS - Sound Absorbing use: walls, screens, baffles, dividers
- PET ACOUSTIC PRINT PANELS -Sound Absorbing use walls, screens, dividers
- PET ACOUSTIC PATTERN PANELS - Sound Absorbing use: walls, screens, dividers
- PET ACOUSTIC CARVED PANELS - Sound Absorbing use: walls, screens, dividers
- PET ACOUSTIC 3D PANELS - Sound Absorbing use: walls
- PET ACOUSTIC CEILING - Sound Absorbing
- PET ACOUSTIC SCREEN: Sound Absorbing use: fixed screens for work desk or dividers
- PET ACOUSTIC FLEX-SCREEN (Speech) Class C 0.60 (60%) (Cellphone Ring Tone) Class B 0.80 (80%) Sound Absorbing use: mobile desk-screen, partition screen, wall-hanging