Updated: May 28, 2020
The word audism first appeared in 1975 by Tom Humphries. It was coined to explain a specific kind of discrimination that Deaf and HOH (Hard of Hearing) people experience. Much like sexism, racism, and any other ism, Audism is specific in a way to Deaf people, that most Hearing people are not aware of. It typically means: 1. The notion that one is superior based on one's ability to hear or behave in the manner of one who hears. 2. A system of advantage based on hearing ability 3. A metaphysical orientation that links human identity with speech. -- (1) Tom Humphries, (2) Wellmann (1992), (3) Deaf Studies conference by Bahan and Bauman, 2000.
Some examples of Audism are:
"A Deaf administrator told me this: a [hearing] parent had come to his superior objecting to their child being placed in a classroom headed by a Deaf teacher. The superior listened for a half hour of parental concerns about speech modeling and so on, then incredulously exclaimed, 'You want to prevent your child from becoming a teacher of deaf children, too?'" -- Dianrez, 2011. 
The best educational experiences that many Deaf children have are the Deaf teachers and a few hearing teachers who are fluent in ASL and have excellent attitude toward Deaf children, such as the belief that Deaf children are as fully capable as hearing children.
A few more examples of other behaviors of audism in employment are: hiring a hearing person over a better qualified deaf person for a job position; dismissing a job application without giving a deaf person an interview when she/he may be the best worker...
Other examples of audism on language: judging a deaf person's English when not knowing that she/he may be an immigrant; judging Deaf people how well they can hear and speak when they can read and write English well at the graduate level...
It's important to know and understand that Deaf people see themselves as a linguistic-cultural ethnic group and they are all human beings with intelligence and human feelings no different from hearing people.
Some things I see in my everyday life are students speaking in front of me, to each other, while I am teaching a class. This is audist behavior, and is extremely rude when in Deaf space. Deaf space is space that is carved out specific for ASL and signing, with the presence of one of more Deaf. If you are talking in class, the teacher cannot have access to your conversation. It basically ignores and takes advantage of the Deaf person not being able to hear.
To put this into terms that Hearing people can understand, it would be as though everyone around you is signing, and you have no idea what is occurring. You will feel left-out, and imagine if this were occurring in your own house. You would be very upset! So, in future, do not leave Deaf people out. If you do not know sign, try to find a mutually beneficial way to communicate with them, such as writing, or via an interpreter. Fyi, lipreading IS NOT communication.
Lipreading is a common misconception, and an audist behavior as well. It is assumed that Deaf people can "read lips" to understand the conversation. However, lipreading is very unreliable; that is to say, only about 3 out of 10 words, or 30% of speech can be seen on the mouth. It also further places a heavy burden on the Deaf individual for communication. They must work extra hard to try to figure out what is being said. Therefore, this is not an effective way to communicate with those who are deaf.
So, where do you stand? Have you been audist in the past? How can you be mindful in the future?