I like some of the suggestions already here, but I strongly disagree with a point about the ADA. This is a great link, btw.
Yes - the employer absolutely has to work with you to provide a "reasonable accomodation".
But - the employer does not have to be psychic, and does not have to provide accommodations unasked for. In fact, to do so can be seen as treating employees unfairly and it can also be a huge waste of time. For example, a person with a speech impairment may sound like someone who is deaf from birth, but they may actually hear quite fine and require no hearing related accommodations - so getting them a sign language interpreter would be both useless and insulting.
To work out an accommodation you have to:
A - Choose whether you want the employer to be aware of the issue. This is a very personal choice, and relates to how much help you need, what the risks of disclosure are and how badly the lack of help will impact your performance.
B - Figure out thoughts on what options work for you and be ready to recommend them. Asking, with no offers of ideas, for an accommodation may mean that you get a suboptimal solution.
C - Realize that it's not "any accommodation" it's a "reasonable accommodation" - a company like IBM may be able to afford an interpreter on staff, and that's quite reasonable with 5-10 deaf employees around. A 10 man shop with 1 deaf employee may not be able to afford the extra salary, but may be able to get by with cheaper alternatives. So be ready to discuss alternatives and listen to counter offers
Ideas for Hearing Impairment
I went to RIT, which is colocated with NTID (the National Technical Institute for the Deaf) and I worked in student government with deaf students at all levels of interaction. I realize that the deaf to hearing communication skill set isn't a one size fits all, so ability to sign, ability to lip read, etc. go hand in hand with the individual's experience.
Things that I've seen that work, particularly for someone who can here ... some... but who has a hard time in groups or with other auditory interference:
Appoint a moderator for the meeting and follow a more rigorous speaking pattern - like Robert's Rules of Order. Pass a speaking stick if you have to - but restrict communication to a more 1 to 1 like interaction. This actually benefits the whole team - the number of time ideas get missed or skipped because the conversation got fragemented into subgroups is pretty significant.
With a moderator, it's much easier to get people to clarify their speech, speaking slower and clearer so you have a better chance of hearing it.
Have a note taker. In this day and age, it could even be possible for the note taker to touch type notes that are broadcasted via a Web Presentation or on a projector so that EVERYONE can see and agree to the notes as they are taken. For agile development, some forms of progress are documented very briefly by sticky notes, which may be OK, so long as you can see the sticky notes, see the movement and are clear on what the progress means.
Agree on SOME cases where having it written down is beneficial for the team - for example, a blurb on stories, use cases, requirements, or a specific "how-to" document may be useful for everyone, so getting the team to the habit of documenting work that helps everyone is a real win overall and not just for you.
Ask for individual communication in written form first so you can prep and respond that way as your most efficient means. And work with the team to find as many text-based mechanisms as can be supported in the company - email, wikis, IM, text message...
The trick is how much you want to make your manager and your team aware of the need for accommodation. You will be asking people to change their patterns, but they will get a more fully interactive team (with you in it!) and the benefit of your insight and support in a way that you couldn't before. That sounds like a fair trade to me and worth the effort - but it's your choice on how much you want to keep your condition private vs. asking for help.