Dr. med. Eckhard Hoffmann:
Hearing ability and hearing defects among young adults

Aulweg 123, D35392 Gießen, Germany

Ladies and gentlemen,

it seems every time there is a radio interview about hearing ability and hearing defects, the radio hosts come up with the same, apparently very funny joke. After one or two sentences from me they say: "I beg you pardon?"

So is this joke really an original idea of the hosts? Doesn't it rather show in an unreflected manner the deep-rooted stereotype that not being able to hear well and not understanding the message intellectually are almost exactly the same thing? Even for radio host, dealing with the topics "ear" and "hearing ability" is often coined by inconsiderateness although they use those very canals for their shows. Young people pay - and certainly rightly so - a lot of attention to their outfit. It is important that the heels of their shoes have the right height, and the brand of their jeans and the rest of their styling should be according to the latest trend. Young people keep stressing the meaning of visual reception; usually their opinion is unanimous: we live in a world that is determined by perception. Hearing on the other hand is taken for granted and on a first look doesn't seem to require a second thought. Of course music and discos play an important role, but since it is very loud in those places, young people don't care too much whether they can hear in such a situation or not.

Young people often overlook the meaning of the hearing ability for controlling the environment, to transmit information and especially for social communication.

The hearing research group at Justus-Liebig-University under the direction of Dr. Fleischer has been dealing for years with the investigation of hearing defects among young people. At the moment questions such as "What damages a primarily intact ear throughout the course of life? What are the special dangers for the ear? How can the precious hearing ability be protected in a most effective way?" are our main focus. Throughout our research we have questioned about 6000 people of various ages and tested their hearing ability. In numerous campaigns we have developed models for prevention and applied them in a practical way. For example we attended several times the international music fair in Frankfurt with a special show. The response to campaigns like the music fair in Frankfurt where every time very remarkable. For example the visitors where willing to wait for as long as an hour in order to participate in one of our hearing tests. At a techno concert in Giessen we experienced that the young visitors didn’t ignore our info table or make fun of it but rather showed interest and made use of offers such as free hearing protection devices. The key idea for all our campaigns was to give out information in an interesting manner, without a strong moralizing undertone.

So, in my opinion, the fact that a lot of times there is only a rudimentary knowledge about the own hearing ability is not so much a sign of a general indifference. Much rather it seems to be a lack of information which is presented in an interesting way and directed towards certain target groups.

The research of our group is always divided into three steps: First there is an extensive interview with a questionnaire. That is followed by a careful audiometry to determine the hearing ability. Finally there is a personal consultation. It is important to us that we don’t only receive data for our own research as we interview the people but that we also explain the results of the tests to the individuals. Consequently everybody receives a printout of their test so that he or she has the result and thus the possibility to watch the development of the own hearing ability over the course of time.

The interview is held before the hearing test in order to eliminate the possibility of the test result influencing the answers. The two-page questionnaire tries to determine the strain which noise has on the ears at work and in the free time. Since our main focus is on young people, music plays an important in the questionnaire. For example we inquire about the number of visits to a disco per month, the length of a single disco visit and the number of disco years. Of course we are also interested whether the volume of the stereo is turned up widely every now and then, which type of music is mainly listened to and how many concerts are frequented. At the same time we ask about ear sounds (tinnitus), possible acoustic traumata and ear infections.

The hearing test itself is performed in our audio-truck. This truck is the construction of our research group to enable the mobile and flexible execution of the tests. There are four soundproof cabins in the trailer which grant an excellent condition for the measurements. This makes it possible that four people can absolve the test at the same time. In the audio-truck the hearing ability in the frequency area between 125 Hz and 16 kHz is measured. The standard hearing test at a doctor’s office or at a hearing aid shop only covers the area up to 8 kHz. The extension of our examination presents a meaningful supplementation for our research. Some patterns of damage are more easily classified with the inclusion of this high frequency area. At each test, well-trained audiometrists determine carefully the threshold of the hearing ability of nearly that whole area. A real measurement of the threshold of the hearing ability is performed. In opposition to many screening tests which initially check only whether a certain sound can be heard at a certain volume, our test really measure the actual threshold at which a sound gets from the inaudible to the barely perceivable area.

In the last container there is a doctor’s office which for one thing contains the necessary equipment for a medical examination and also offers a quiet atmosphere for the consultation. Via a computer network the result of the hearing test is directly printed out in the doctor’s office and is there explained individually to every body.

The evaluation that I would like to present to you today relates to a group of 424 young men between the ages of 19 and 21 years. These were examined by us at the beginning of their military service at the first or second day. Thus they had experienced hardly anything of their time at the German army and hadn’t touched any weapons yet. In parts the examinations apply also to a larger group of 1670 people at the age of 18 till 25years.

So what does the hearing ability of young adults look like? At the age of 20 years the threshold of the hearing ability should ideally lie on the zero-mark. In the fifties and sixties the threshold of the hearing ability of young adults of this age group was tested. People with hearing defects and an excessive noise stress where excluded. The median of the thus determined hearing thresholds became by definition the zero-mark. In this first evaluation a hearing loss of 20 dB or more will be counted as a hearing defect. Only 40% of the 424 young men were able to hear well on both ears at all frequencies. That means that their maximal hearing loss amounted every time at the most to 15 dB. 60% showed at least at one frequency at at least one ear a hearing loss of 20 dB or more. 22% of the whole group had the hearing loss at the area of the "classical audiometry" up to 8 kHz. These numbers match well with the other current scientific studies. The hearing loss affected in single cases not only the area up to 8 kHz, but there was an additional loss in the extended area of the high frequencies of 9 – 16 kHz. So a damage in the area up to 8 kHz is usually linked with a damage in the area between 9 – 16 kHz. On the other hand a good hearing ability in the area up to 8 kHz isn’t necessary a guarantee for a good hearing ability in the higher area. 38% of the people who have a good hearing ability in the normal frequency area have a hearing loss of at least 20 dB in the area of high frequency.

Are the affected aware of their hearing loss? In our questionnaires the test persons judged their hearing ability prior to being tested. The results showed that the subjective judgement of the own hearing ability and the real hearing ability often have a wide discrepancy. Thus the subjective judgement of the hearing ability is not a reliable parameter for the hearing ability. I have the example of a 17-year-old student for you. In the questionnaire she stated that she thought she had normal hearing ability. The following test revealed that this 17-year old Turkish girl was deaf on her right ear. Further investigations confirmed this result. The cause for this defect couldn’t be found. In a subsequent talk the young woman said that she didn’t have any problems due to the deafness on her one ear. Even after further questionings she maintained that she wasn’t aware of any restriction, like in a loud environment. There was a similar result with another girl of the same grade. This student had become deaf on her left ear after an infection in her early childhood. The hearing ability on her right ear was normal. During the conversation the 16-year old told that she was sitting in the first row at school because otherwise she would have difficulties following the explanations of the teachers. Especially when several people were talking at the same time she had difficulties to participate in the conversation. At home, when the cordless phone was ringing, it would take her a while to find it if it wasn’t at the usual place. If one compares the two young people, one notices how different the perceived consequences of the same medical report are.

Many hearing defects develop over the course of time. Usually a very slowly developing hearing loss is realized at a very late point by many of the concerned. Usually it is the environment that brings the loss to the attention by saying things such as "Are you deaf?" In every day life a person has hardly anything to compare the hearing ability to, if you put aside the case of a sudden hearing loss, for example one due to a sudden deafness. Thus, the personal acoustic perception seems to be always the norm to us. We usually suppose that that, what we experience in our environment, what we hear, see, smell, and feel, is encountered in a similar way by our neighbor. What justifies this assumption? Probably everybody has experienced the case where one has undergone a certain situation together and afterwards in a conversation had to realize that the perception and the interpretation of the same was very different. Possibly this was followed by a heated discussion about the "right way of seeing things". In such moments language offers us a chance to assimilate our perceptions to a certain degree. How and what our neighbor perceives from the world will always stay hidden for us for the largest extend. Also for counseling it is important to remind yourself that everybody perceives the world in an individual and unique manner. We are often tempted to force our own perception onto others. Let’s not forget: If the perception of someone else seems strange to us, then the same is most likely the case vice-versa. Unfortunately I can’t go more deeply into this very interesting topic with all its implications.

Thus let’s go back to hearing defects. So where do those damages which can be seen so often come from? A distribution of the observed hearing defects into patterns of damage makes first conclusions possible. Depending on the pattern of damage, conclusions to the cause are possible. For example hearing damage in the low frequency area, as could be seen with 30%, are often caused by ear infections.

Especially chronic middle ear infections can have a negative effect on the transmission of sound in the middle ear with its components, the eardrum and the ossicles hammer, anvil and stirrup. Literature tells us that hearing defects in the middle frequency area are usually caused genetically. But not a single person that we examined here claimed that their parents or other close relatives had hearing problems from young age on. Hearing defects in the area between 3 and 8 kHz are usually considered to be caused by noise. This is especially the case when a distinct depression is to be seen in the audiogram. However, hearing defects in the high frequency area may also be seen after the intake of ototoxic (harmful for the ear) medication. Certain antibiotics and also some chemotherapeutics that are used for the treatment of cancer belong to the group of ototoxic medications, which may be injurious for the hearing ability. If possible, these medications are avoided nowadays. But if their use is required, the hearing ability is constantly checked upon.

Almost all the audiograms of the here examined young adults with a hearing defect in the high frequency area showed a typical depression. The maximum of the depression, the point of the highest hearing loss, was to be found between 4 and 8 kHz. Some of these depressions were very distinct and showed a hearing loss of more than 50 dB. Taking the known pattern of hearing loss into account, one has to suppose that the overall majority of the found hearing defects in this age group are caused by noise. Since the professional career of these young adults was yet at its beginning or hadn’t even started yet, the job couldn’t be the cause for the hearing loss at this age group. Thus, the free time activities were the main focus of the search for causes. Music is usually named first in the discussion of the possible causes for these noise-caused hearing damages of young adults. But is music really that harmful for the ear?

In our interview we asked the test persons to name their hobbies and to estimate the noise stress at a scale with 5 steps from 1 (very quiet) to 5 (very loud).

With a clear lead, visiting discos is the number one of the free time activities. This is an inevitable part of the free time culture of young people. Playing soccer, computers, car and motorcycle, biking and reading follows it.

Almost 80% of young people go to discos on a regular basis. They constitute an important meeting point, establish a suitable place to present oneself and one’s clothes and represent a location which is a little bit suspect to a lot of parents. The latter makes them even more attractive. Research has shown by the way that opposed to the general opinion, discos are not places that establish a lot of social contacts. A psychologist told that a doctoral candidate had watched for a year the visitors in a disco. She came to the conclusion that those men and women who had entered the disco by themselves usually left it alone as well.

Regarding the noise stress, discos were the number one of all free time activities. The visits to discos determine overall the noise dose of young people. Those young people that were interviewed by us stated that since their sixteenth birthday they approximately visited discos once a week. The usual length of a visit was 4 hours. The noise stress during a visit to a disco is enormous. According to our own measurements the typical noise level at a disco is 103 dB. For comparison: A pneumatic hammer produces a noise level of about 100 dB. The noise dose which a young person experiences here in 4 hours is equivalent to that of some employees at a loud working place in a whole week. At a single intensive techno weekend the noise dose can reach a caliber which is equivalent to the noise stress of half a year working with a noise stress of 85 dB.

If we compare on this slide the extreme disco visitors who, as 20 year-olds, have already spent more than 2000 hours in discos, with those people who have never or almost never visited discos, we see a surprising result. Here we see the average audiogram of both groups in the frequency areas between 250 Hz and 16 kHz. The lower the average, the worse the average hearing ability is of this group. Of course we expect that the group with the higher noise stress will have worse results then the group which doesn’t have the noise stress. The here shown comparison-group doesn’t only avoid discos but also doesn’t use Walkman and doesn’t visit concerts. If you compare these two groups you will notice that there are no differences which are worth mentioning. That means that the extreme disco visitors don’t have a worse hearing ability than those who don’t enjoy music. The interview made it obvious that the group who doesn’t visit discos now does not consist of people who do so because their hearing ability is already damaged.

As an example for a representative of the group with a high noise stress I brought you the here shown audiogram. This 19 year-old man visits discos 8 times a month for 3 to 10 hours and on top of that visits 10 heavy metal concerts each year. His hearing ability is perfect. And this is not a long searched-for exception but to my own surprise rather the norm. I could show you a few more evaluations under the aspects "listening to the Walkman" and "visiting concerts". The results are comparable; the sought-after music effect was not to be found. I can assure you that at the beginning of the study it wasn’t my goal to prove that damage mechanisms of music plays only a minor role. I was very sure that I would find a music affect. For now the provisional result which can be seen is on one hand that there are a lot of hearing damages to be found with young adults, but on the other hand there is no correlation between those hearing damages and music consumption.

About half of the interviewed young adults answered the question if they had ever experienced ear noises such as ringing or whistling with yes. But for the overall majority these noises were only temporary; however for 4% of those concerned by tinnitus it was permanent. The interview showed that most of the people regarded the noises as quite normal. Several times I got this reply: It is totally normal that you have a whistling in your ear after being in a disco or at a concert, isn’t it? If it doesn’t whistle, it wasn’t a good concert. Hardly anybody gets the idea that that noise might be a warning signal of the hearing cells. Since the noises disappear usually after a short while, people don’t experience them as a threat but rather as a side effect. A clear connection between the ear noises and music can be seen. While out of the whole group 53% said that they had experienced ear noises at some point, 59% of the disco visitors, 64% of the concert visitors, 68% of the people who listen to a Walkman and 73% of people who enjoy all three activities said the same thing.

As we were searching for possible causes of the observed hearing losses we noticed that half of the interviewed people stated that they had experienced an acoustic trauma. A so-called acoustic trauma distinguishes itself by two main symptoms: Immediately after a loud bang the affected experiences a distinct hearing loss and feels either right away or some time later a ringing or whistling in the ear. As the most common causes for such an acoustic trauma fire crackers and blank pistols were named. Out of the manifold world of bangs I would like to add slaps. In some circles boxing someone’s ears is still considered an appropriate means of education. The sudden closure of the ear with the flat hand can cause a remaining hearing damage. Without regarding the other aspects of slapping as a means of education, one should refrain from using this just because of the danger of damaging a child’s hearing ability.

The audiogram that I’m showing here shows clearly the consequences of a bang. This 21-year-old high school graduate told about the explosion of a firecracker right next to his right ear. Just like most affected people he didn’t see a doctor about it. This is also a sign for the fact that most people underestimate the danger of hearing damages and the consequences of hearing damages. The audiogram for the right ear showed a very typical form of a one-sided hearing loss. The maximum of this hearing loss was found at 8 kHz, the hearing loss at this frequency was 65 dB. By including the high frequency area the depression character of the hearing loss becomes obvious. If one would have only measured the hearing ability up to 8 kHz, one would have supposed that there was a pure high frequency hearing loss.

This clearly developed hearing loss shows a strong discrepancy to the fact that a lot of people still consider it to be very funny when a fire cracker is lit in such a manner that it will explode right next to somebody’s ear.

Throughout our research we also started paying attention to toy guns. Especially at the time of Mardi Gras there are a lot of little cowboys wandering through the streets, armed with toy guns and shooting like crazy.

Since fall of last year we have started measuring the top sound levels of toy guns with a specially constructed measuring system and interviewing affected children and testing their hearing ability. We found distinct hearing damages that were caused by commercial toy guns. Some of the affected children had to stay for days in a hospital and receive infusions. A hearing loss and an in some cases permanent tinnitus remained.

Toy guns are sold for little money in every toy store with the imprint "Not for children under 3 years of age." For our measurements we imitated typical playing situations with an artificial head which was constructed for noise measurements. Here, the "worst case" is especially important: A child holds a toy gun directly at the ear of another child and pulls the trigger. You can see such a case in the graph. The toy gun was fired right next to the artificial head. The top noise level of the here shown pressure-time course is 186 dB. For comparison: A pneumatic hammer produces an enduring noise of about 100 dB, in a disco the average is about 103 dB, and a G3-rifle of the German army has at the ear of the marksman a top noise level of about 168 dB. The toy gun that we used for our measurements surpassed all these by far. And that even in concord with the presently valid norms for toys. The hearing damage is thereby approved. Of course a child wants to scare its playmate with the toy gun, but it certainly doesn’t want to permanently damage him or her. Therefor we demand reasonable threshold values for toy guns so that the children’s ears will be safe from permanent damage. Especially with young children this damages often stay unnoticed and untreated because they aren’t able yet to express themselves adequately and because a lot of times parents don’t recognize and evaluate the danger in an appropriate way.

On the next slide you can see further evidence for the cause of the seen hearing damages. For the evaluation of the causes we should at first point out those 37% whose damage probably wasn’t caused by a noise event. This is true for the group that has hearing loss in the low frequency area as well as the group that has hearing loss in the middle frequency area. For the high frequency depressions that are typically believed to be caused by noise it attracts attention that the overall majority of these hearing losses occurs only on one ear. This is very typical for hearing loss caused by impulse noise because usually the ear that is closer to the bang is clearly more affected. Of course a bang can also cause hearing damage to both ears, if it is coming from the front or from behind. With discos, Walkman and concerts on the other hand one would expect to find hearing loss on both ears since the young people usually have both ears involved in that. Since the one-sided hearing damages outweigh those on both ears, one is lead to believe that the often-found hearing damages are rather caused by bangs. So one can realize that the effects of loud music to the hearing ability have often been overstressed whereas the effects of bangs were rather underestimated.

The danger of bangs is that they almost always appear unexpected and thus it is hard to defend oneself against them. In one instant a bang can cause a life-long damage to the hearing ability.

The risk for people who already have a hearing damage is especially high. For once a person who has problems hearing has a much smaller chance to locate an event which could lead to a bang. And secondly a further hearing loss can be devastating for such a person. The only positive thing is that a hearing aid can have the effect of a protection against the bang. The high peak of the pressure is weakened by the built-in limits and the ear piece of the aid can further mute the sound like an earplug. But the danger of jeopardizing the precious rest of the hearing ability can not be underestimated.

Let’s now come to the conclusions and consequences. Young people usually don’t pay a lot of attention to their hearing ability. It is a sense organ which seems to function without the need for any attention and which therefor doesn’t require any care. But without the appreciation for the own hearing ability a sensitive way of dealing with people with hearing problems is impossible. As long as a healthy ear doesn’t mean anything, the loss of the same doesn’t mean anything either. Thus an understanding of the consequences of hearing loss and the resulting restrictions for a person with hearing loss requires the confrontation with the own hearing ability. Therefore I find it a very important and essential goal to inform children and teenagers about the efficient and precious sense organ ear from a young age on. But the information is only received if it is attractive and geared for the target group. The information should already start in kindergarten because this is where especially at the time of Mardi Gras, when the little cowboys walk the streets, the first dangers are hiding. A beautiful children’s book about the ear is the result of a masters thesis. In a sensitive and informative way it tells the story of the hearing cell Hörbert. Unfortunately is hasn’t been published yet as a children’s book. The ear is not like milk teeth which will later fall out, are replaced and which give everybody a second chance when brushing the teeth. Thus it is important to guard the hearing ability at an early time.

Throughout the time of going to school the students should repeatedly be reminded of their ears with the help of good aids. One of them is a hearing test on a regular basis which is explained to the students and which gives them a feedback about their own hearing ability. The screening hearing test that is used before the children get enrolled into school does not fulfill that function.

The hearing research group has developed a simulation of hearing loss to use it for young people. It is easy to simulate the loss of eyesight by simply closing the eyelids. Our ears don’t have lids, and even ear plugs only dim a part of our acoustic impressions. In order to make it possible to directly experience what it is like to have hearing loss, we used an acoustic workstation with specially developed software. The simulation doesn’t only take the hearing loss into account, but also the changed impression of volume, the recruitment, which occurs with many people who suffer from hearing loss. Thus everyone can hear language and music with the ears of someone who has a hearing damage. We use examples of popular music from the hit parade. Young people are thus able to experience with their own music what severe consequences hearing loss has. A life simulation of hearing loss is possible if the acoustic workstation is connected with an artificial head, the loss of three-dimensional perception is thus demonstrated effectively. I have seen many thoughtful faces after these demonstrations.

My wish is that especially young people will realize the value of their hearing ability and will henceforth protect it out of their own interest and will deal responsible with their own hearing ability and that of their neighbors and thus will have an open ear for the specific problems of people with hearing loss.