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Sennheiser on Headsets & Hearing Damage: What You Should Know


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March 23, 2006

Sennheiser on Headsets & Hearing Damage: What You Should Know

By Stefania Viscusi, Assignment Desk Editor


As developments in headset design continue to advance, wearing a headset, especially for extended periods of time, has become more comfortable. But what many users fail to understand is that wearing a headset "comfortably" means more than not feeling like its being worn. In fact, without the right protection, wearing a headset can expose users to a number of hearing related difficulties.
Most recently, headsets were given attention in the news for the possibility that they could damage hearing when used for listening to music at loud, lengthy intervals. For call center workers however, the risk is even greater.
Because call center workers usually wear headsets for a much longer period of time, they are much more likely to experience the dangers associated with hearing loss, such as Acoustic Shock Syndrome and Excessive Noise Exposure.
Recognizing the seriousness of this danger, many headset manufacturers are stepping up to develop products that protect users. Sennheiser Communications, provider of headsets for the telecommunications industry, is one such company offering protection specifically for call center agents.
TMCNet had a chance to speak exclusively with Bjarne Nordahl Hansen,  Market Manager Sennheiser Americas about acoustic shock syndrome and what Sennheiser is doing to prevent headset users from the damaging effects.
How serious is the problem of hearing loss in relation to noise exposure?
During the course of a day, headset users may be exposed to hazardous incoming noises that can be dangerous to the hearing. The sudden high-pitched signal of an alarm sounding at the other end of the line, for example, can be more than frightening – it can actually cause irreversible damage and pain. Technically referred to as an acoustic burst, a sudden and unexpected variation in sound level can potentially cause long-lasting damage to the human ear. This can lead to acoustic shock, which can cause symptoms such as headaches, tinnitus, and even loss of hearing.
This is a serious problem especially for frequent headset users who are exposed to high levels of noise exposure on a daily basis such as, in call centers or other telecommunication jobs it is almost certain in these situations that over a period of time a person will experience hearing problems because of excess noise exposure. 
Can you briefly explain the dangers associated with Acoustic Shock and Excessive Noise Exposure?
Sound intensity, or loudness, is measured in decibels (dB)-- a logarithmic scale. To take into account the frequency sensitivity of the ear, workplace noise intensity measurements are usually given in dB (A)-- where 0 dB (A) is the threshold of hearing. Pain is felt at around 140 dB(A).
-Normal conversational speech: 60 dB(A)
-A classroom of primary school children: 74 dB(A)
-Heavy road traffic: 85 dB(A)
-A pneumatic drill: 100 dB(A)
-A jet taking off 100 meters away: 130 dB(A)
In call centers, and other workplaces, workers can be exposed to acoustic shock. Defined as a sudden increase in high frequency noise transmitted through a headset, this noise can be caused by interference on the telephone line. Exposure to these shocks can cause pain and harm to the ear, as well as being a factor in work-related stress.
Unexpected high-level sounds have been reported to cause a variety of symptoms. Symptoms that have been reported during the exposure include discomfort and pain. In the few minutes after the exposure, symptoms include shock and nausea. Occurring for sometime after the exposure are: headaches, nausea, tenseness, and hypersensitivity (discomfort) to loud sounds that would previously have caused no problems.
The mechanism causing the adverse symptoms is not known with certainty. It seems highly likely, however, that the sound exposure elicits an acoustic startle reflex. When startle occurs, numerous muscles in the upper limbs, shoulders, neck, eye and ear (the stapedius muscle and the tensor tympani muscle) are activated. If the noise exposure is loud, or if the person is in an aroused state (e.g. anxious, fearful) prior to the startle, the magnitude of the muscular response is heightened. It seems likely that the ongoing symptoms are the after-effects on the muscles and ligaments caused by the muscles being tensed to an unusual degree.
What has Sennheiser done specifically to address this issue?
To safeguard users from these imminent dangers, all Sennheiser Communications telecommunications headsets are equipped with ActiveGard technology.
This built-in, patented technology safely compresses potentially dangerous sound levels, whereas traditional systems simply clip off high noise peaks. ActiveGard allows headset wearers to work more relaxed in the knowledge that their headsets are equipped with this technology to help ensure their safety.
Before an undesirable incoming signal even reaches your ears, the ActiveGard technology acts as an automatic control in your headset to instantly lower the volume of unacceptably loud, high, or deep sounds. Using sophisticated electrical circuits, the energy of the acoustic burst is actually removed and not just reduced. At the same time, the sound itself is compressed without distorting it. When the volume reaches acceptable standards again, it is allowed to return to the original, comfortable level. The automatic guard then returns to surveillance mode.
What is the European Noise Directive and how is it affecting the present and future standards involved in headset design?
The European Union’s Noise at Work Directive, effective since February 15, 2006, lays down new rules for protecting hearing on the job and draws increased attention to these problems worldwide.
The directive basically deals with two types of noise induced hearing damages: Acoustic Shock and Excessive Noise Exposure throughout a working day.
The directive defines two critical levels for noise exposure throughout a working day. For up to 80dB(A) the employer has no obligations. Between 80dB(A) and 85dB(A) the employer should offer hearing protection and education. For levels exceeding 85dB the employees must be provided with and wear hearing protective equipment.
The directive also sets a limit to the sudden loud sounds associated with acoustic shock. The limit is 135dB(A), which is comparable to standing next to an airplane taking off.
In my opinion, the effect this has on the development and design of headsets today and in the future is not great, however. These developments do not seem to have a large impact because other companies are still continuing to create headsets that use traditional systems for noise cancellation.
 Are there certain rules involved in protecting people’s ears?
Yes. For example the European Noise Directive, is a law that all EU member states must follow.   Standards are set by the European government for countries to abide by. This means that in factories, building sites, offices and other practices laws have been made concerning the noise levels in certain areas. 
Various other regulations apply to noise or include specific provisions on noise, including: the Management of Health and Safety at Work Regulations 1999; the Provision and Use of Work Equipment Regulations 1998, the Supply of Machinery (Safety) Regulations 1992 and the Agriculture (Tractor Cab) Regulations 1974.
The same rules apply to concerts and other public events where noise can be a problem. In public areas frequent tests are done to measure noise levels, this is done to see whether people surrounding the event are not bothered with excess noise pollution and also to see whether people at the event are exposed to large noise levels.
Where do you see the future of headset design in relation to protection from noise exposure?
Protection from noise exposure will play an important role in sales of headset products. The actual design of headsets will not be affected greatly. As I mentioned the technology used by Sennheiser Communications to reduce noise outbursts is so small that the design of the product will not be compromised.
The quality of the sound and speech are very important aspects when consumers make their decision in buying a particular headset. The design plays an important role as well but being able to hear and speak clearly to the person on the other side of the phone is just as important.
Sennhesier also provides a SafetyZone on their website, this area gives consumers the opportunity to find out what the latest laws and regulations are concerning noise levels and the solutions for these regulations.
Sennheiser Communications uses Oticon technology that specializes in hearing aids audio logy. Specifically, at Sennheiser technicians are testing and using Oticon technology in their products. This gives Sennheiser products a competitive advantage to its competitors because of the know-how that is supplied by Oticon.
In this way, Sennheiser can continue to focus on the design and aesthetic aspects of their products while still providing superior hearing and sound technology.   
Stefania Viscusi is an established writer and avid reader. To see more of her articles, please visit Stefania Viscusi’s columnist page. 

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