I'm not deaf. But I want to make a clear a case that might come up to mind when discussing EA topics.

Note : I use the word « deafblind » here due to uncertainty on whether part or all of deafblind people identify as protactile. I've been encouraged by my sign language linguistics teacher to prefer « protacticle » to refer to the specific community self-denominating themselves as such, which do not encompass all deafblind people, hence my usage of the later expression.

1-The two problems

Two of the critiques of EA I've already heard is the following :

-Ilnesses should be prioritized to the extent that they imply tradeoffs, such as is mirrored by QALYs : if one were to trade, say, one or two years of life to recover from deafness, then it means that deafness is a negative experience, which implies that it oughts to be cured, rather than accepted and welcomed in society.

-What constitutes a moral patient is its ability to experience sentience, which in turn rests on different subjective experiences. Thus, deaf people count « less » than others.

Now, there is no question, for me, that both of these conclusions are clearly audist and should be worrisome if implied by EA. However, I think that they are not, and I think it is important to make clear to the deaf community that they are not, and that they should not be worried about EA. If an EA were to be headed in a country, be sure that they will not consider the deaf community as a relic of the past needing to be abandonned, replaced by ever-so functional gene therapy and hearing implents.
 

2-Preference utilitarianism

Again, as a disclaimer : I don't really consider myself a classical utilitarian. But I think that this is the view that is assigned by outsiders to EA, so I think tackling this is more important than tackling the issue with other ethics.

The first objection I'd have to these implications is preference utilitarianism. If one is to define wellbeing as being (at least in part) defined by respecting one's preferences, then it doesn't really matter what QALYs are associated with deafness from birth. What matters is what QALYs are associated with one's deafness from birth, and I deem it completely acceptable that someone would say that they are fine with their deafness and wouldn't trade their identity (let alone lifetime) for a wider auditive spectrum.

I'll suggest a parallel here (but I'm in no means saying this is equivalent in severity and hardhsip) with sexual orientation. I personally have a preference for people of the same sex and gender than me. I'd theoretically be happier if I were to be attracted by a more diverse set of people, even more so if I were living in a homophobic region of the world. However, even if I were living in a culturally homophobic area (which I did), I wouldn't prefer to trade my homosexuality for, e.g, bisexuality. It is, after all, my personal preference. If I were presented with a magical pill that allowed me to feel attracted by a larger set of person, as things stand by now, I think I wouldn't take it, because it would make me feel (very) guilty of obeying social pressures rather than being a positive force for changing them.

3-Robust wellbeing

But I'll go farther than that. I think that hedonistic utilitarianism also implies that we shouldn't automatically cure deafness at birth. There is a certain tendency among detractors of utilitarianism to think that utilitarians have a very monochromatic view of pleasure. A +45 util does not feel several possible ways, it feels only like what a +45 utils feels. I think this is misguided. As humans, we have several modal fields (vision, hearing, touch, enteroceptions...). There is virtually an infinite number of ways of experiencing a +45 utils, through one modality or a combination of several, and this diversity, utilitarians claim, has no bearing on moral imperatives when facing tradeoffs.

Still, one might say, if I were to experience +45 utils in all modalities except for audition at time T, and then experience +45 utils in all modalities including audition at time T+1, then it should not be regarded as morally wrong to « cure » someone from deafness without their explicit consent (such as is usually attempted soon after birth in countries such as France). I think that not requesting consent is generally wrong, even when considering act utilitarianism. The reason is that, as Singers points out in Practical Ethics, there is a difference between merely sentient beings and persons. Persons have their wellbeing affected by their plans, projections in the future, and the fullfilment of those. A deaf person who is proud and willing to be deaf has a continuous fulfillment of their plan to stay deaf. When transforming this person into a hearing person, one does not face a merely sentient being, and thus harms them by causing them to stop this, sometimes deeply meaningful, fulfillment.

Now, granted, they are still infants when they receive an implant. But people implanted at birth often regard back to this event with ambivalence and sometimes regret. It's not like an abortion, where the aborted fœtus cannot look back on its abortion and think about it.
 

4-Unintended consequences

Another worry an act utilitarian can legitimetaly have is that curing deafness in reality is not that effective. When implementing an intervention, such as implenting hearing aids to deaf infants without their consent, the initial cost in theory and in practice stays relatively fix -namely, it's the cost of the gear and surgical operation. However, the overall benefice in theory and in practice can widely fluctuate. After generalization, doctors can misunderstand the point of hearing aids and think that the child can be deprived from visual linguistic input without any consequences (wrong). Society can conserve its biases and wrong ideas towards deaf people. It can refuse to create adapted venues that are actually still necessary, etc.

I think it probable that being born deaf in our time would be, in an accepting society, not much of a loss compared to being born hearing. For example, deaf signing people seem to have an expanded visuo-spatial awareness that hearing people usually lack. They have their own artforms. If we were to cure deafness, there would basically be a transfer from enjoying deaf artforms to enjoying hearing artforms, from deaf-predominant pleasures to hearing-predominant pleasure, etc. I don't think we would gain anything, and I think that the only net gains to be had are in curing reluctantly acquired deafness and in fighting audism.

5-Hypothetical wellbeing

I'll even go further than deafness in general. Suppose that, after some sort of course of event, we happen to have entirely deleted deafness, and no one remembers what it was. Then, suddenly, a deaf person is born. Through some sort of series of unprobable events, they happen to not be « cured » from their deafness. This person may experience loneliness and confusion, they may lack a sense of belonging, they may feel oppressed. All these experiences are pretty negative. It doesn't really affect me to think that this person exists or not. I think that, in an optimal society, the society itself is ready to react to that kind of events, that no matter the modal differences that characterizes one individual, it is designed in a way that takes it in account. Ideally, if a world were to be post-deafness, I think it would be wrong (in terms of potential suffering, somehow like S-risks) to not have mechanisms in place such as, as soon as a deaf person is born, then sign language education, subtitles, accessibility in general and, of course, their active contribution to shape this accessibility are automatically deployed.

I think this is true of deafness, and of any difference among individuals in general.

6-A thought experiment : the modal marginal overlords.

A philosopher whose name I forgot has made clear the speciesist bias implied by « trait » arguments throught the overlords thought experiment. I invite you to repeat this though experiment with a different kind of overlords, the modal marginal overlords. Imagine that, following a pandemic, the population is suddenly constituted of 98% of special humans. Following a life-lasting genetic mutation caused by the disease of the pandemic, these humans have developped a new modal field of experience, called plussing. Now, they can pluss bananas, sunsets, cities, and many different things that we currently lack the capacity of doing. They find this modality quite useful, and start adapting their society to incorporate it in all parts of their life, such as leisure, work, orientation, etc. They find it so convenient that it progressively replaces vision. Now, there would not be any lamps left, since plusscasters scattered everywhere allow to pluss the environment. Their facial mimics now stand still, and they would plusscast emotions directly to one another.

It would be wrong, in our current eyes, to consider the remaining 2% to be less worthy of moral consideration. No matter whether a -50 utils of information is conveyed through classical senses or an additional pluss sense, it would still be a -50 utils and would thus be bad. According to my hypothetical wellbeing paragraph above, it would also be wrong, in my eyes, to remove public lighting and render society inaccessible to plussless people. However, it would not affect the fact that plussless people who want to be plussing can be offered help in pursuing a technology that allows them to do so, and the fact that acquired plusslessness might also be a medical preoccupation. But it would be indeed absurd to require from plussless people to be implented for them to experience plussness much like plussing people do, and even more so if they experience pleasure in fulfilling their plan of staying proudly plussless, defending such artforms as traditional cinema or performing arts.

7-Deafness is a special case : laws of modal equivalence

I believe that utils are technically affected, primordially, by information. Therefore, as long as the modality one is « deprived » of (in events that keep the brain plasticity and cognitive technology required to communicate) does not prevent informational communication (this thus applies to sound, vision, and the combination of both, since tactile communication is functional), I believe that they do not affect potential utils experienced by a given sentience. I think that, if the people affected decide that they do not want to gain additional modalities, their choice should be respected as such (and I also think that, were someone desiring to lose one of their modalities, their choice should also be respected as such), even under a hedonistic act utilitarian perspective. I also believe that infants should be allowed all options at birth, whether modally restricted or not : ideally, all children should be exposed to oral, written, sign and tactile language. They can thus later decide which modality to prioritize or leave (exception being made for written language, which can be conveyed in all modalities).

Of course, in our world, given the current inequalities and ressource limitations, it is justified to focus this accessibility to children who are hearing- or additionally vision-« impaired ». This, again, ideally means that infants born deaf and deafblind should be raised bimodally. Since we do not live in an ideal world, it is justifiable to prioritize tactile (and arguably sign) languages for deafblind children and sign languages for deaf children. However, it would be wrong to prevent an infant to be exposed to any of those languages, even by motivating such a prevention by the so-called wellbeing of the child. As we saw, developping oneself in one modality rather than three is not a wrongdoing and does not affect the utils one experiences, as long as the choice of the person is respected. The joy of having a child will be the same whether the information, in all its clarity, can be conveyed by sound, sign or tactile patterns in the palm of a hand, or the three all at once.