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Last modified January 1, 2022


Sound, Freedom & Comfort

At this site you can read a lot about unwanted sound, and its title can be easy to misinterpret: Who would want a totally silent PC? No, today's personal computer is a multimedia machine providing those of us having a good sense of hearing with exceptional experiences also in the world of sound.

One of the most important meta aspects of the writing here is freedom: The freedom to choose what sounds your ears and brain are exposed to, and the freedom to compete and profit also on acoustic comfort. Some people don't bother about the kind of sounds most other people refer to as noise: To them these sounds might actually mean acoustic comfort; emphasizing the fact that acoustic comfort, as well as noise, are subjective notions. Everyone should, with appropriate showed respect to others needs, have the opportunity to choose for themselves.

Freedom is as everybody knows a relative notion, and total freedom in the world of sound is of course not only impossible, but would similar to the effects of too much unwanted sound, also be most boring.


The Wider Perspective

a small human earNoiseless information technology equipment can naturally, but doesn't have to be put in a wider perspective: What do we want our surroundings to be like? Do we want an unintentional side-effect of our wealth-creating technology to dominate in what we listen to in all our environments, outdoors as well as indoors? How much are we, how much are you prepared to pay for to minimize this side-effect, at least in your own interiors?

Is unintentional machine and equipment sounds what our impressing ears, the amazing human attention and thought and the nature, deserve to always and everywhere stay exposed to?

Photograph of small human ear ©Tomas Risberg


Gold for Silence

Man's imperfection makes it impossible to avoid all unintentional machine and equipment sound. For optimal wealth, and comfort in other aspects than the acoustic, we most often have to accept to compromise, but probably not as much as we used to.

We now not only see an emerging market for noiseless information technology equipment, which is the main focus for this web site, but also find advertisements for quiet air conditioners, microwave ovens, vacuum cleaners, dishwashers and other kinds of technology being used close to humans.

These days every earphone maker of honor produce active noise canceling ones; intended primarily for comfortable traveling, all leading companies in the automotive industry invest a lot money in low interior noise levels and sound quality engineering, and in an issue of The Economist we see the Airbus® A340 being marketed as "The quietest cabin in the sky" (June 14th-20th 2003 p 10).


Sound comfort in the Airbus® A340 cabin

Comfort in the quiet A340 cabin. Courtesy and © Airbus S.A.S.®


New Product & Service Differentiators

Speech intelligibility and acoustic comfort are quietly - still rarely commented as a phenomenon per se by the World's business press - becomming substantial product and service differentiators. Areas that used to be the almost sole and, because of costs, often ambigously treated concerns for some industrialized nations' government authorities, are becomming big business. Here is a collection of links to this new market:

The acoustic comfort marketplace in general

The Noisy Ape - "Manufacturing CD and MP3 players, radios, TV sets and all the rest of modern sound technology is big business, but there is just as much money to be made from fighting noise..". Louise Fryer investigates our sound environment in a four-part series on BBC World Service Radio.

The noise that annoys - "The demand for quieter products has increased in recent years. Quietness adds value to consumer products, office equipment, and factory machines. Workers want equipment that makes less noise than even the levels mandated by OSHA; they want the same noiselessness in their appliances at home." A mechanical engineering magazine online article.

The global noise control marketplace for the new millenium - "Product noise is increasingly a key factor in the purchase decisions made by many people in various places, for products ranging from consumer goods to industrial and transportation equipment. The challenges of the global marketplace in the coming years will accelerate the demand for quiet products, regardless of where they are built or sold." An article by Bennett M. Brooks, Brooks Acoustics Corporation.

A Global Vision for the Noise Control Marketplace - "Since European manufacturers have more experience with noise as a competitive factor, they also have an advantage over their U.S. counterparts in U.S. markets. Therefore, U.S. manufacturers face a tough challenge from competition that is better prepared to meet the low noise demands of both domestic and foreign customers." An article published by the the Acoustical Society of America.

Noise control - "The impact of noise is often overlooked in process design and engineering, and also in day-to-day operations. Governments are tightening up legislation on noise pollution and local residents are being more vociferous in seeking a quieter environment." A page by Shell Global Solutions.

Measurements and Judgments of Sound in relation to Human Sound Perception - "It is recognized that A-weighted measurements of sound pressure levels and sound power levels alone are insufficient for measurements in relation to product sound quality and noise annoyance potential. This has led to an increasing interest in objective and subjective methods giving results in closer agreement with human sound perception." A page by Danish Delta.

European Environment Information and Observation Network (EIONET) on acoustic comfort.

Aircrafts and helicopters

Neuron networks and acoustic comfort - "Up to a certain threshold, observers have noted that an aircraft passenger's acoustic comfort no longer depends uniquely on the level of noise, but also on its nature. This means that engineers had to develop a new concept, the comfort index, to help manufacturers construct more acoustically comfortable airplanes and helicopters." A page by ONERA, the French Aeronautics and Space Research Center.

Passenger's Comfort - "Noise and vibration as well as air quality and thermal environment are fundamental factors contributing to the passenger perception of cabin comfort, especially in medium and long range flights. These factors are also important for the health of passengers and crew on board." A page by CIRA, the Italian Aerospace Research Centre.

Comfort studies on aircraft interior sound and vibration - "Due to the increased frequent use within shorter and shorter distances, not only safety, maintenance and viability aspects, but rather subjective felt sensations of the passenger in the air vehicle environment have to be taken into account in aircraft design and development." A dissertation by Julia Quehl.

Aeronautics and space research

Auditory Demonstrations II: Challenges to Speech Communications and Music Listening - "Noise affects our lives in many different situations. At high sound levels, ongoing exposure can lead to noise-induced hearing loss. Even at low levels, some sounds can cause annoyance or distraction. Within this continuum lies a vast range of experiences where the chief noise complaint is usually difficulty in understanding speech. The difficulty only increases when the environment is highly reverberant and/or the listener has hearing loss." A page by the United States of America's National Aeronautics and Space Administration, NASA.


Flooring and Acoustic Systems - "The acoustics of a vehicle are critical to success in the marketplace." A page by Lear Corporation, the world’s largest automotive interior systems suppliers.

Noise and air in motion "Interior noise is an important factor for many purchasers of luxury vehicles. The passenger’s impression of comfort is determined to a large extent by the sound quality and how quiet the car is." A page by TNO TPD; part of the Netherlands Organisation for Applied Scientific Research TNO, the largest independent research institute in the Netherlands.

An annoyance meter for Squeak-and-Rattle diagnostics - "Notions of robustness, safety and product quality are more and more related to auditory sensations, notably as concerns components of automobiles and domestic appliances." A page by French Institut de Recherche et Coordination Acoustique/Musique.

Vehicle Noise Pass-by Measurement System - "On side of usual Pass-by measurements ruled by community noise standards, cabin acoustic comfort has become a major concern for car manufacturers." A page by SCS International. It seems to be an acoustic counsultancy company.

The New Volkswagen Acoustics Centre in Wolfsburg - "Acoustics and vibration have a huge influence on a vehicle's impression of comfort."

Automakers Invest in New Technologies to Lower Vehicle Noise Levels - "..Japanese automakers build the quietest vehicles in the world. Compared with cars, trucks and motorcycles produced nearly 30 years ago, manufacturers have reduced vehicle noise by 90 percent. They’ve achieved this by investing in new technologies that reduce tire and engine noise(s)." A page by Japan Automobile Manufacturers Association.

Interior Noise Reduction - Attacking sound at the source - "Customers are beginning to make greater demands for quieter automobiles, and because of this, automakers have begun to attack sound inside the passenger compartment with greater ferocity." A page by Automotive Industries; a monthly publication devoted to providing global coverage of all aspects the automobile marketplace, with an emphasis on the people, products and processes that shape the industry.


Engineers Tread Toward Quiter Tires - "Tire noise and vibration are both a nuisance and a consumer issue because they account for much of the unwanted noise heard inside a car, as well as outside..". A page by Global Technoscan, a weekly magazine on new technology and international business.


Motorsport - "The ambient audio levels created by modern racing cars is similar to that of a jet engine and in the case of many types of single seater race cars, the driver is very close to the exhaust. It is therefore essential to have a highly efficient earplug system to minimise potential problems that may be caused by engine and wind noise. Combine this with the need to listen to radio communications it is therefore very necessary to have an in-ear solution to take care of these demands, whilst being comfortable for long periods of use." A page by Sensorcom, a company that specialises in the design and manufacture of audio communications accessories for use in difficult and abnormal conditions.

Motorsport intercom systems - "The world's leading motorsport teams have been using Peltor Intercom systems for over 20 years. This experience has given us the opportunity to design the ultimate in rally intercom systems. This durable, high fidelity system produces the best sound quality even in the most punishing of environments." Peltor® is a trademark of Aearo Company who specialises in safety products, safety prescription eyewear and specialty composites.


Quiet Revolution Motor Company, L.L.C - "The desire to develop quiet efficient engines for lightplanes has been the driving force behind our Stirling engine improvements. We expect these same advances to serve markets such as silent sailboat powerplants, silent motorhome generators, silent lawnmowers, and a host of other applications."

JAGUARDIESEL - "Continuous adjustment of Minimum Drive Pulse (MDP) means the Jaguar X404 diesel engine actually 'learns' how to be quieter the more it is driven." Tiscali.Motoring writes about the Jaguar X-TYPE 2.0D.

Heavy equipment

Helping to make your heavy equipment quieter - "Operators of heavy equipment such as graders, bulldozers, earthmovers and cranes spend their entire work day in and around equipment. A environment that provides for reduced noise levels increases operator effectiveness and improves output." A page by Technicon Industries, Inc, specialist in noise control materials.


High-Speed Trains - "As the key player in the development of the Shinkansen bullet train vehicles in Japan, Hitachi has taken part in all Shinkansen rolling stock projects. Design and production of a light aluminium body, a VVVF inverter unit, ATC control and other such instruments along with the Hitachi laboratories' outstanding engineering capacity have been brought together to make it possible to provide a comfortable moving space characterized by low noise and low vibration that is perfectly adapted to the environment through which the tracks pass." A page by

Simulator for optimising train passenger and crew environment - "Passenger and crew comfort, performance, health and safety depend on a complex combination of reactions to noise, vibration, and the thermal environment." A page by Rail Research UK.

Buildings in general

Qualification of the Degree of Acoustic Comfort in Multi-Family Buildings - "To most people, acoustic comfort is a vague concept that becomes clear only when they are dissatisfied. The vocabulary that builders use to describe the acoustic comfort from which future tenants will benefit is just as inadequate; they often refer to “superior” soundproofing, which is very difficult to define in a legal context when occupants are not satisfied and turn to the courts to exercise their rights." A text by Canada Mortgage and Housing Corporation, CMHC.

Quiet Comfort - HVAC Systems and Acoustics - "In today’s competitive economy, worker productivity is critical to success. A great deal of new technology is devoted to improving productivity, but one of the simplest and most obvious factors is often overlooked – noise." A page by


A Knowledge Based System for Comfort Aanalysis of Internal Environment of hotels - "The most important aspects of comfort analysis of internal environment of hotels are to maintain lighting comfort, acoustic comfort, thermal comfort and indoor air quality." A text by Dr Rabee M. Reffat and Mostafa M. Aref, King Fahd University of Petroleum and Minerals, KFUPM, Dharan, Saudi Arabia.

Hotel One Aldwych - London, United Kingdom: "Extremely high acoustic specification gives the guests the desired comfort, as the rooms are exceptionally quiet and protected from the busy London main road noise." A text by Bovis Lend Lease, one of the world's leading companies in the project management and construction services industry.


What is a high performance high scool? - "Acoustic comfort means teachers and students can hear one another. Loud ventilation systems are eliminated, and the schools minimizes outdoor and indoor noise from reaching the classroom. " A page by CHPS, The Collaborative for High Performance Schools in California.

A new standard for Acoustics in the Classroom - "Improving the academic performance of U.S. students depends, in part, on our ability to create "learning-friendly" environments." A page by Trane, a company that provides indoor comfort systems and comprehensive facility solutions for residential, commercial and industrial building needs.

Acoustic ceilings and wall absorber systems

Ecophon - "Ecophon is the leading supplier of acoustic ceilings and wall absorber systems in over 40 countries. Our mission is to contribute to a high-quality working environment, for the eye, the ear and the mind. We build-up leadership by delivering superior end-user values in offices, educational premises and health care premises."


Tarkett® "has taken a stand against noise and proven that pure decoration and true comfort can be brought together in a laminate flooring." Tarkett is one of the largest producers and distributors of resilient floorings world-wide.

Acoustic muffling mats - "For a long time structural engineering could develop without any greater consideration to the acoustic environment. Now, we can see a totally different path where the demands on the acoustic characteristics of the building are highly prioritised. A number of acoustic demands have also been created." A page by Aprobo AB, a company that deals mainly with flooring products.


Technical Committee on Sound White Paper: Product Labeling and International Standards - Implications and Benefits of an ARI "Labeling" Procedure - "..What is new, however, is the need for a standardized “labeling” procedure to be followed when determining a sound rating number for a product that can be designed, tested and manufactured any place in the world. Without an ARI “labeling” Procedure in International HVAC Sound Standards, the sound rating information provided to the end user will not be in a comparable form between different manufacturers or locations. A document by ARI, The Air-Conditioning and Refrigeration Institute. ARI is the US national trade association representing manufacturers of more than 90 percent of North American produced central air-conditioning and commercial refrigeration equipment.

Domestic equipment

Electrolux® Ultra Silencer vacuum cleanerElectrolux pulls the plug on noisy vacuum cleaning - "Power and performance have always been accompanied by noise, but as a result of years of research and development Electrolux has been able to solve this problem and create a high performance vacuum cleaner which operates quietly."

Electrolux is the world's largest producer of appliances and equipment for kitchen, cleaning and outdoor use. Electrolux is also one of the largest producers in the world of similar equipment for professional users.

Electrolux Ultra Silencer, a powerful and yet comfortable vacuum cleaner.
Courtesy and © Electrolux®

IT equipment

Intel® Acoustic Overview - "Evidently, the acoustic performance of a system is a product differentiator. System performance, size, cost, and acoustic performance are closely related. Therefore, the acoustic design goal depends on the product positioning in the market."

Cobalt3™ - "As heat and noise have become a serious design issue in consumer electronics, Cobalt3 is currently expanding its operations by creating a diverse range of services in the design and development of thermal acoustic solutions for enterprises in the Consumer Electronic Sector."

The new growing market for noiseless IT equipment is the main focus of this web site. The Solutions page show some of all these new products.

Medical Systems

MR Specialists Opt for MR Systems Designed To Enhance Patient Comfort - "Almost ninety percent of the group, which represented both hospitals and imaging centers, said they prefer systems that significantly reduce acoustic noise and increase the patient aperture (the area within which the patient is confined during a scan)." A page by Toshiba America Medical Systems.

Sound quality engineering

The Trademark Registrability of the Harley-Davidson Roar: A Multimedia Analysis by Michael B. Sapherstein.

Product Sound Quality – from Perception to Design - "This article on product sound quality is concerned with the relationships between the work of product designers and the perceptions of consumers regarding the acceptability of product sounds." A page by Sound and Vibration, a practical engineering magazine.

Design Sounds - "Design not only concerns function and appearance – it is also about sound – something which so far has not been much discussed in a design context. But with our increasing everyday use of technology – such as alarm clocks, microwave ovens, hairdryers, computers, cars, tools, toys and mobile phones – sound is becoming a more and more important part of design." Design Sounds is a Swedish exhibition. You can download some most interesting documents there.

Designing Product Sounds - a page by Ingemansson, the leading expert in Northern Europe in the area of acoustics, noise and vibration.

Design News - The sound of quality: "Today, OEMs regularly perform sound quality analysis on both their own and competitors' previous successful models to determine which components are causing the "pleasurable" sounds that can be reproduced or even enhanced in future models."


Reforming the Acoustic Comfort Market Place

It can be a bit hard to understand, that even while optimized acoustic comfort most often is part of high-quality products like expensive cars, the most luxurious home and hotel environments, and ergonomic thinking in high-tech working environments where every risk for human error must be minimized, we often still have not simplified the possibility to make buying decisions on this aspect: The relative notions "quiet" and "almost silent" are still mostly not paired with comparable figures. Talking on this we must keep in mind that the notions decibel (dB) and bel (B) also are relative ones; if their figures aren't accompanied with information on how they have been obtained.

There are some international noise declaration standards that already are quite easy to understand and use, like the ISO 9296 [1] standard for IT equipment, but why should we have to learn different noise declaration interfaces for each of all product groups? A further problem to solve is that, invented already in the 1930s, the A-weighting filter still represents the only commonly used little effort to adjust dB and B figures to how humans in common apprehend different sounds: Sound quality metrics are only rudimentary covered with A-weighting.

Improved freedom in the world of sound will be achieved when we decide to reform its market place - A simple to use universal product noise declaration and labeling standard that also includes sound quality metrics awaits its invention. More on this subject can be read at the Noise Labels page.


Sound Visualization

Humans can not close their ears. For us this means that the shutting out of unwanted sound has to be made at brain and nervous system level.

The systems shutting out unwanted sound at brain and nervous system level did not evolve in the kind of acoustic environments most people in the industrialized part of the World now face. These parts of the human brain and nervous system therefore now show their weak points in that today's suboptimal acoustic environments often adverse affect us. Nontheless will most humans not be aware of these effects of unwanted sound: This because the systems shutting out the unwanted sound, primarily were intended exactly for the very task to keep useless acoustic information unconscious.

Due to the unconciousness built-in in the human sound processing system can visualization of unwanted sounds be a way to understand them better. Product noise declarations according to international standards, like the ISO 9296 [1] standard for IT equipment, can be one way to visualize unwanted sound, but there are also other means:

SoundPLAN - "It is much more economical to cope with noise problems before they arise."

Acoustic camera – listening with the eyes - "The first step in making the environment more comfortable and quieter is an efficient and detailed analysis of noise sources."


The Meaning of the Information Society Notion

Even if not as often as in the 1990s, we still say that the industrialized part of the World now is in the era of the information society or knowledge society; also named the information age. There are no accepted definitions of what the information society, the knowledge society and the information age stand for, and many have questioned the relevance of these notions. In many countries has the problem to fill these notions with content resulted in a tendency to replace them with the notion of the "IT society", ie the information technology society.

The information society notion can, however, be filled with more content than being an era where we manufacture, sell, buy and use information technology equipment: The ways our computer technology and the human brain work are often used as metaphores for each other. If we look upon the capacity of the human brain as the main difference between us and the rest of the World's animals, and tries to understand what it needs for to work as efficiently as possible, will we probably be able to better understand what we mean with the information society. This implies that we in the information society notion include a need for information to be meaningful.

Information not carrying any meaningful information can be regarded as noise; here is the word of course used in a wider sense than only acoustic noise. Meaningful information, on the other hand, can be said to be a signal. In the information society we need an as high as possible signal-to-noise ratio at every possible level. The realization of the information society thus not only requires technology cooperating as close as possible with the needs for the human brain, environments as good as possible for living, working, teaching and learning, but also humans that communicate as optimal as possible with each other.

Man's imperfection and the fact that we live in an imperfect World makes all this hard to accomplish, but we have the power to improve.


Soundscapes & Acoustic Ecology

The word "soundscape" was coined by R. Murray Schafer in connection with the World Soundscape Project that he established in the late 1960s at the Simon Fraser University, Vancouver, Canada. The goal was to understand our sound environment.

Schafer, a musician, composer and former professor of communication studies suggested that we should try to hear our acoustic environment as a musical composition and further, that we own responsibility for its composition.

Schafer's thoughts was the beginning of a new field now known as "acoustic ecology".

Further reading

The World Soundscape Project: an article on the history, thoughts, ideas and visions behind the project.

Is Acoustic Ecology About Ecology?


Man's First Soundscape

Humans start their hearing life in their mothers' wombs. A fetus as young as 20 weeks is capable of hearing. In scientific articles the intrauterine sound environment is often labeled as a noise environment. Here think about the fact that noise is defined as unwanted sound.

It seems we still know very little about Man's first sound environment, even if it isn't that complicated to study it.


PC Sound Links

E-MU 1212M sound card

The high ranked E-MU® 1212M sound card.

The E-MU® 1212M internal sound card has October 2004 been choosen one of the best internal sound cards ever evaluated by the Swedish sound conscious hardware reviewing PC magazine Mikrodatorn.

Audacity is a free audio editor released under the GNU General Public Licence. You can record sounds, play sounds, import and export WAV, AIFF, and MP3 files, and more. Audacity is available in Windows®, MacOS® and Linux/Unix® versions. - "The objective is to build up a knowledge base around new ways of listening to music using a computer and discovering and sharing the advantages of it."

SawStudio "combines both high-tech virtual mixing and hard disk editing technologies into one power-packed application. The look and feel of a fully controllable console, coupled with an all new high powered 24-bit hard disk engine make this product one of the most intelligent choices for the serious audio professional."

The Musician's Guide to Home Recording: "This site is for those of you who want to make your own demo recordings at home, and have them sound just as good as $50 to $75 an hour project studio productions."

Afrotech's Hard-disk Sound System: "Why pay 500$ for Klipsch's latest speaker system? You can make something that looks way cooler for the price of a DIY amplifier and some HDDs out of a dumpster." A SlashDot discussion about it.

AUDIOTRAK: "The goal of AUDIOTRAK is providing professional quality DTMP (Desk Top Music Production) to musicians who just started hard-disk recording and theater-quality DTHT (Desk Top Home Theater) to the movie goers, who want to build a theater system around their computer." Tom's Hardware has reviewed the AUDIOTRAK Maya 7.1 Gold sound card and concludes: "At a dynamic range of 90 dB(A), Maya provides some of the clearest signal quality of all sound cards available. On-board AC97 solutions usually provide between 75 and 85 dB(A), which is simply not enough for everybody who wants crystal clear recording or playback at almost all volume levels."

Linux Audio-Quality-HOWTO

Soundcard tips and facts

Sound Builder is a sound synthesizer for Mac OS X: "You can use your sounds as alert sounds for Macintosh, sound effects for multimedia works and music projects, or can edit with other sound editor, because you can save the sounds as AIFF files."

KinkyBeep is a Macintosh shareware program to create ones own system sounds. It's intended for MacOS 9.x and below.


Miscellaneous Sound Links

EWALD - Exciting World of Acoustical Links from Denmark: A comprehensive collection of interesting sound links.

Associazione Italiana Fonomatori - "AIF, Associazione Italiana Fonoamatori, is a cultural national organization, which was born in Parma in 1967, aiming at gathering together all those people who are interested in sound recording both from the technical point of view and from the artistic-creative one, without making a profession of it or beside theirs."

Grooved Whale: "The following pages contain thoughts and ideas I have gathered on the physics, philosophies and peculiarities of listening underwater."



1. International Standard ISO 9296:1988 (E) "Acoustics -- Declared noise emission values of computer and business equipment"


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