The following is a translation and slightly expanded version of the post written in my mother tongue. However, as internet posts are living organisms, I will make little efforts to keep the german and english version totally in sync. As our master program is in English and since we do have quite a few master students from abroad, and since the problem came up particularly in the last two semesters, I think a translation might be appropriate.
You might have noticed. The link on my homepage shows my name in (german) fingerspelling. There is no way to beat around the bush. I am quite hard of hearing and have gotten into the habit of being quite open and direct about it. This is not meant to be intrusive or pushy. Rather it is the only way to avoid possible misunderstandings.
I would like to give some information concerning the communication with me. At the same time it can hardly be overlooked that there exist quite a few common misconceptions about hearing disabilities. Some of them are even fueled by misleading advertising. I will also comment on this.
Concerning terminology. In the german language there exist at
least three words for people who are
hearing impaired but emphasizing that
there is a damage (Schaden)),
hearing but often used in the context of elderly people where it is
not clear whether there is only an auditory or also a cognitive problem)
hearing disabled but probably
hearing impaired). In german I neither like
hörgeschädigt (I don't think I do have a damage, the german pun
roof damage, is a not very friendly way
to question a persons cognitive abilities) nor
(I think I am mentally still very clear).
So after these lengthy explanations I think in
English I go with
hearing impaired, as the more appropriate
hearing disabled probably sounds too foreign. I am not
particularly politically correct, so inventions like
challenged sound silly to me. I would like to emphasize, however, that I
consider myself to belong to the group of people with disabilities and that
I am particularly concerned about inclusion.
Hearing aids are (not) like glasses. The most common misconception is the belief that hearing aids are similar to eyeglasses. Someone who has poor vision buys glasses and (usually, not always ), he/she then simply sees sharp again. The advertisement of a large german hearing aid dispenser chain, with a well known face from the entertainment industry, suggests that a hearing aid completely restores hearing and that one can then even enjoy concerts again. Nothing could be further from reality than that.
A hearing aid is nothing but a crutch. A pretty good one though, but still a crutch. Nevertheless, I am of course glad and grateful to live in these times when these devices exist. Just a few decades ago, things were very different. 
We'll then just talk a little louder
This jovial, perhaps friendly meant, but nevertheless quite condescending
statement goes straight to the pit of the stomach. Being hearing impaired
has also but by far not only to do with volume. It exists at every
age and the association with the somewhat disoriented elderly
gentleman is inappropriate by all means.
In any case, the defects of the hearing system are usually very complex.
On the one hand they affect the frequencies and inevitably on the other
hand also the dynamic range. I.e. the thresholds are raised depending on
the frequency (i.e. one hears a pure tone only from a higher volume) which
automatically compromises the dynamic range (because 120db is an absolute
bound for the human ear). Even if the hearing thresholds, which is rarely
the case, are horizontal lines, linear amplification (
we are just
talking louder) is not really an option .
Counterintuitively, in case
of a hearing impairment, the thresholds of discomfort (i.e. volume levels
which are perceived as unpleasant to painful) can even be lowered. In sum,
the hearing aid must on the one hand raise the poorly heard
frequencies, but on the other hand make sure not to exceed the thresholds
of discomfort. This means that the original dynamic range gets
compressed substantially, sometimes by several orders of magnitude (note that
the db range is logarithmic). Now you should get an idea why this
cannot become a hearing pleasure. The only criterion is to restore
speech recognition, pleasure is not a category here.
The bottom line is that despite bad hearing one can be quite susceptible to noise. In particular it is not only rude but outright unacceptable to yell at a person with a hearing disability (it is unacceptable anyway).
When you turn off the hearing aid you can work in quietness. (I would be willing to give a lot if this widespread misconception were even remotely true.) Mathematicians in particular like to work quietly, so can hearing loss even be an advantage? Well, at least it does happen (I actually know a person who wears cochlear implants  and who perceives total silence if she turns them off, but this case is exceptional), but most acquired hearing loss comes with severe ringing in the ears (tinnitus) . This would be a topic for another post, which I might write later. Only so much: should you be affected by ringing in the ears, you are very welcome to talk to me for a sober advice. But you should avoid the advice which appear at the top of an internet search. With all this advice, in the end you will be rid of time, nerves and money, but certainly not of the problem.
I just did not notice that you are wearing hearing aids,
to me you appear to be hearing normally.
This is a truly poisened praise.
Firstly, I intentionally bought rather big devices because they
have more features and because the
13 battery lasts for 10 days. These devices can hardly be
Secondly, after this praise it will even be more difficult to
ask for help (tenor:
we just don't understand what his problem
is, he does understand). Thirdly and most importantly, for a hearing
impaired person speech recognition is high performance sports. People with
normal hearing just understand on the fly and effortlessly and hence can do
other tasks in parallel. For us a substantial part of the mental and
cognitive energy is absorbed by the process of speech recognition. Note that
in the end one understands with the brain and for us speech recognition
consists of the interpretation of text containing more or less gaps.
This is why after a workday one is simply exhausted, indeed quite
exhausted. Openly admitting this is not easy and doing so bears
the danger of being to ones disadvantage at the workplace.
On the other hand, trying to get along somehow sooner or later
leads to frustration and overburdening, even without noticing it
for a long time. This is also one of the reasons for making this
I prefer conversations in a quiet environment without ambient noise and in relatively small rooms without reverberation. Thanks to my equipment I do have little problems to understand in such environments. Furthermore, it helps me a lot if I can see the faces of my conversation partners. Though I can't read lips, the lip movement provides valuable additional information. The pandemic was hard enough for all of us, for the hearing impaired in particular. With the end of the pandemic I consider it just offensive if people still insist on wearing masks even while talking in a meeting.
Probably, it is just your right to show up in my office hour wearing a mask. But you should not expect me to understand much of what you will try to tell me. It is up to you whether you consider then such a conversation as meaningful .
Furthermore, it would be nice of you if you did not speak too fast. As explained above, one understands with the brain and for me this often means to interprete auditory gaps.
For a couple of years now I have been unable to understand whispering language. Don't even try to whisper something at me: I won't understand you anyway.
Making phone calls remains a challenge. In a quiet environment
I do have little problems. But a
cold call somewhere in a noisy
environment is impossible. Therefore, I prefer if phone calls are arranged
in advance by email.
Should it happen that I just do not react: bevor you think that I am rude consider the most obvious first: I just did not hear you or did not understand you. Sometimes even I am a bit shy to repeatedly ask if I did not understand you.
I usually avoid big gatherings (e.g. before the colloquium), not out of rudeness or lack of interest, but because it is acoustically meaningless.
Meetings in small groups, e.g. in the Hausdorff room are more or less unproblematic. However, if in summer the windows are open the street noise is more than annoying.
Unfortunately ideal conditions are not always possible. For me not much can be worse than the meetings in our large meeting room. The room does have a strong reverberation, the people spread out in the room and worse sometimes remain seated behind masks while talking. Honestly such inconsiderate behaviour makes me really angry, in particular since some of the actors are particularly engaged in equal opportunity issues and therefore should just know better. In such meetings I am out, in fact completely. But also the hallways in our building are difficult for me because of their strong reverberation. To try to tell me something across the hallway is pointless in most cases.
In a lecture, the lecturer speaks most of the time. Nevertheless
students might have questions, and this is a real challenge.
All our larger lecture rooms do have a difficult acoustics
and in the best case I can only understand questions
uttered from one of the first few rows. In case of questions
from further behind I usually ask that someone from the
translates for me.
In the past this has occasionally lead to irritations and
misunderstandings. I am open to better solutions. It would be better to
have a microphone to pass around.
In seminars, unfortunately, we do have the situation that regardless of where I sit down there will be participants whom I will have great difficulties to understand (e.g. because they are covered by someone or because I see them only from behind). Here we have to rely on good will and creativity to solve the problem.
In exam situations the whisper problem (see above) becomes relevant. If someone has a question he/she does not want to disturb the others and hence the normal reaction is that he/she whispers at me. I can't help, in these situations everyone else has to accept, that the conversation must take place at a subdued but essentially normal volume.
Let me be frank here. Hybrid meetings are a disaster, also because, as a taxpayer, it really annoys me what the technology costs and how little it achieves. The room microphone (sic) only transmits voices of people sitting next to it and even this in surprisingly poor quality. People sitting further away cannot be understood, unsurprisingly not by me, but I have even witnessed normally hearing people having their difficulties to understand. Occasionally, when being external referee I have asked for a script interpreter for the hybrid meetings. The excuses I have heard were interesting and show that the willingness to embrace inclusion wanes very quickly when one realizes that it costs more (not only money but also time and efforts) than to pay lip service.
I neither have a problem nor do I feel uncomfortable to talk openly about these things. On the contrary I am glad about interest in the matter. Also I would like to exchange ideas with other affected people. For more than 10 years now I have been an expert on bad hearing and I will gladly share my experiences concerning noise protection, technology, rehabilitation opportunities and support groups. Also about tinnitus I do have a certain expertise and I could e.g. provide a talk about it. However, there is one thing I certainly cannot do: to free you of it. In any case you are very welcome to come and talk to me.
Matthias Lesch, 14.07.2023, last update 26.08.2023,
 In the vast majority of cases, eyeglasses are used to correct an aberration. I do not deny that there are vision problems that cannot be corrected by glasses. Fortunately, they are rare.
 It is an inconvenient truth that hearing aids have their
price, in my case about 6000 Euro. Of course health insurances consider
this an undue luxury and refer to the most basic devices available as being
reasonable and customary. I can speak only for the german system where I do
rely on the state employee indemnity system (Beihilfe) and my private
supplementary insurance. But I do think that the phenomenon is basically a
universal one. With devices considered
reasonable and customary
by the bureaucrats I could probably exist but almost certainly
with them I could not do my job. Personally, I have no reason to complain
about finances. However, for many people a hearing problem can also become
quite a substantial financial burden; and this on top of the fact that it
severely compromises the quality of life.
 I have oversimplified here a little. In rare cases (some cases of conductive hearing loss) a linear amplification might indeed basically solve the problem. The vast majority of cases, however, concern a sensorineural hearing loss. And here one faces the difficulty that there are natural limits for amplification in order not to add damage to the already compromised ear.
 A cochlear implantat (CI) is a neuroprosthesis. The auditory perception then takes place by bypassing the outer ear by means of direct electrical stimulation of the inner ear. Speech recognition must be retrained, however, and success cannot be guaranteed.
 For me the hype about devices
as small and as
invisible as possible is hard to understand.
Unfortunately, a hearing problem is still associated with a stigma and
so the vast majority of customers want devices that are as small and
invisible as possible. The market delivers what the
customers demand, unfortunately at the expense of quality.
The next generation of devices will no longer be available with a
13 battery slot. Rechargable batteries for hearing aids,
the manufacturers are pushing for them, have to be recharged every
night, sometimes even during the day.
 As far as the tinnitus is concerned, I should probably resist to provide any links. This is a topic on which there exists a lot of misleading information on the Internet. Many people have it, the hearing impaired anyway, but also many apparently normally hearing people (me too. Most of the time I have made peace with it. But even after many years it does not always work out). Even if your neighbor should tell you something else: there does not exist the slightest approach to a causal therapy. But there are a lot of quacks out there who try to make profit on the many desperates. And of course you will always find somebody who convincingly tells you that sugar pills (you know ones without effect beyond the placebo effect but with stored information by shaking, tapping, and diluting, cp. [Böhmermann], a German invention of the 18th (!) century), a certain health practicioner, oxygen therapy, Gingko, listening to the inner me, noiser (i.e. pooring oil on the fire, the last thing the damaged ear needs is additional stress), cortison infusion (only the German's seem to believe in this), laser therapy, spiritual healing, osteopathy, traditional chinese medicine  etc. etc. has helped for sure.
I do not have to tell you that evidence cannot be deduced from hearsay. Consequently, acceptance and habituation is the gold standard. I will be glad about every email. However, protests from tinnitus quacks (excuse me ... experts) will go unread to spam, except if they come with an independent study giving evidence for an effect beyond the placebo effect. I will then happily report on this in public.
 Some of this list may be good for something. Even if only to give the patient some attention and to secure employment and income for the provider. Some of it, however, is just charlatanism. And there is one thing none of the concepts can do for you: free you of subjective tinnitus. Only you can do that. It is a shame that the health industry makes money on all the nonsense and apparently nobody really seems to care.
 Don't get me wrong. This text is written in August 2023 after all Corona measures have expired. I am not at all questioning the necessity of the Corona measures that were in effect during the pandemic.