You may have noticed that people who are deaf sound a little different than people who aren't deaf.
It's not easy to explain the difference, as it depends on the individual person. Deaf children growing up with cochlear implants or hearing aids -- with the help of speech training -- often develop voices that sound the same as a hearing person's. In other words, their voices cannot be identified as coming from a deaf person.
My own speech has been described as having a monotone nature. Being unable to hear exactly what normal speech sounds like, despite intensive speech therapy, meant that I grew up without learning natural inflections in speech. With effort, I can give my speech some inflection, but most of the time it is a monotone. Hearing people can tolerate listening to me for a short time, but not for a long time because a monotone voice has a droning nature that can really bother people.
Another term that has sometimes been associated with deaf speech, is "guttural." The dictionary defines guttural as being related to the throat. In other words, guttural deaf speech sounds throaty. I don't know if my own speech sounds guttural, but I have personally felt insulted if someone describes it as that way, because the word "guttural" is often used in conjunction with the word "animalistic."
In addition to what it sounds like, intelligibility (how clear the speech is) is another characteristic of deaf speech. Speech intelligibility is a frequent topic in deaf-related journals. In 2007, the Journal of Deaf Studies and Deaf Education published a report by an Israeli author who compared deaf Israeli children in special classes (group inclusion) in regular schools to deaf children who were mainstreamed (individual inclusion) into regular classes. The author's study involved 19 deaf children. Of these children, 10 were in a special class using speech and sign, and the other nine were mainstreamed and used speech only. The children were asked to rate themselves on two scales: a Loneliness and Social Dissatisfaction Questionnaire, and a Sense of Coherence Scale (Coherence meaning confidence). The Loneliness questionnaire included statements like "I have nobody to talk to in class," and the Coherence scale included statements such as "when I want something I'm sure I'll get it." Then the deaf children recorded spoken readings, and hearing children who had never heard deaf speech, were used as judges of the deaf children's speech intelligibility.
The author was looking for any relationship between speech intelligibility and how the deaf children felt about themselves. The study's results showed that there was no difference between the special classes and mainstream classes with regard to loneliness and coherence. However, results also showed that while there was no significant relationship between speech intelligibility and the children's feelings in the special classes, there was a significant relationship between speech intelligibility and children's feelings in the mainstream classes.
That backed up the author's review of the literature, which found that hearing children had better attitudes towards deaf children with better speech intelligibility. The literature review found that speech intelligibility affected the ability of deaf children to form friendships with the hearing children. Based on the literature review, the author concluded that good speech intelligibility was a necessity for friendships in mainstream classrooms.
Most, Tova. Speech Intelligibility, Loneliness, and Sense of Coherence Among Deaf and Hard-of-Hearing Children in Individual Inclusion and Group Inclusion. Journal of Deaf Studies and Deaf Education. Volume 12, Issue No. 4., May 21, 2007. http://jdsde.oxfordjournals.org/content/12/4/495.long. Accessed April 2011.