Types of accessibility
Venues must be accessible to wheelchair users, but information must be accessible to persons who are Deaf or hard-of-hearing, blind or have visual impairments, and persons with various information processing difficulties (e.g. some persons with learning disabilities).
A key is to assure adequate notice so that people with disabilities can know how to request adjustments in a timely manner. Any information/publicity about an event should include information about the accessibility of an event and how to request adjustments.
Most adjustment requests will be about communication (e.g. for attendees who are deaf, hard-of-hearing, or blind), food (e.g. allergies), and physical access (e.g. arranging aisle seating or wheelchair-accessible seating).
Following is suggested wording for situations where you wouldn't want to just arrange sign language interpreters or real-time captioning without requests.