Author: Dolly Bhargava, M. Spec. Ed.
It is important to understand each specific type of hearing impairment in terms of the continuum of degree of hearing impairment. The degree or severity of impairment ranges across mild, moderate, severe and profound. Sometimes a hearing impairment may be borderline between two categories, such as “moderately severe” (Northern & Downs, 2002). Having an understanding of the student’s degree of hearing loss is useful for determining the types of supports that will be required.
It is important to note that the parameters of these categories are not universally accepted and different authorities may assign different degrees of loss to each category. However, for our purposes, degree of hearing loss will be classified using the descriptions given below. First, it is important to understand that sound is measured by its loudness or intensity (measured in units called decibels, dB). The greater the number of decibels the louder the sound. For example, a 70 dB sound is much louder than a 30 dB sound. A person without a hearing impairment can hear sounds ranging from 0 to 140 dB. A whisper is around 30 dB. Conversations are usually 45 to 50 dB and with background noise, about 60-65dB. Sounds that are louder than 90 dB can be uncomfortable to hear. A loud rock concert might be as loud as 115 dB (Marschark, Lang, & Albertini, 2002). Sounds that are 120 dB or louder can be painful and can result in temporary or permanent hearing loss.
The following information has been collected from a range of sources: Dugan (2003), Lysons (1996) and Pagliano (2005):
A. Normal Hearing
- Threshold - Children with hearing thresholds (softest sound that the child can hear) for both ears that fall between 0 to 25dB are said to have hearing within normal limits.
- Can hear – The child can hear all speech sounds.
B. Mild Hearing Loss
- Threshold - Children with hearing thresholds between 26 to 40 dB have a mild hearing loss.
- Can hear - The child with a mild hearing loss can hear sounds of 26 to 40 dB or louder. He/She will be able to hear the vowel sounds a, e, i, o, u as well as most consonants clearly.
- Hearing difficulties - Consonants, especially voiceless consonants such as p, h, f, s and th are not heard clearly. Speech that is especially faint, distant, rapid or with background noise present will be difficult to understand.
- Speech – A child with mild hearing loss learns speech through hearing. The child may have some speech production difficulties. The child will benefit from speech reading, favorable acoustics, hearing aids, and/or a personal FM system, and speech therapy (professional support for understanding and producing speech and language correctly). Speech and language may develop normally in a child with a mild hearing loss.
C. Moderate Hearing Loss
- Threshold - Children with hearing thresholds between 41 to 70 dB have a moderate hearing loss.
- Can hear - The child with a moderate hearing loss can hear sounds of 41 to 70 dB or louder.
- Hearing difficulties – The child will miss most of the speech sounds at conversational level, without a hearing aid or other technology to amplify sound. Due to inaccurately hearing sounds and missing sounds completely, children with a moderate hearing loss may have a language delay (i.e. limited vocabulary, difficulty with grammatical rules, word meanings, multiple meaning of words, and word placement in a sentence). The child will have difficulty understanding speech in group situations.
- Speech – Speech articulation of the student with moderate hearing loss may exhibit omitted and distorted consonants (Northern & Downs, 2002). The student will require sound amplification by hearing aids, assistive devices such as personal FM systems and favorable classroom acoustics. In conjunction with this, the student will require auditory training, speech reading, and speech therapy.
D. Severe Hearing Loss
- Threshold - Children with hearing thresholds between 71 to 90 dB have a severe hearing loss.
- Can hear - The child with a severe hearing loss can hear sounds of 71 to 90 dB or louder, such as a vacuum cleaner or lawn mower at close range.
- Hearing difficulties – No sounds can be heard at normal conversation level, without a hearing aid or sound amplification technology. The student may benefit from a cochlear implant. If a severe loss is not detected at birth, or shortly thereafter, language and speech will not develop spontaneously and learning difficulties may arise.
- Speech – Students will use speech reading, hearing aids and/or sign language to communicate. If a severe hearing loss is identified early, and the child is fitted with hearing aids, auditory training and speech therapy are provided, the child has a more positive outlook for speech and language development and overall learning. He/She may also use technology such as text phones, and loop systems.
E. Profound Hearing Loss
- Threshold - Children with hearing thresholds from 91 dB or more have a profound hearing loss.
- Can hear - The child with a severe hearing loss can hear sounds of 90 dB or louder such as a chain saw at close range or the vibrating component of loud sound.
- Hearing difficulties – No speech sounds can be heard without amplification by a hearing aid or other amplification technology. The student may benefit from a cochlear implant.
- Speech – The student will use speech reading, hearing aids, and/or sign language to communicate. He/She may also use technology such as text phones, FM systems and loop systems. It is essential that the student has a favorable acoustical environment. The student may also benefit from the use of a sign language interpreter and/or a notetaker in the classroom.
Chapter 1: The Spirit of Inclusion
Chapter 3: Technological and Medical Interventions
Chapter 4: Teaching Strategies and Accommodations
Chapter 5: Activities
Chapter 6: Social Skills
Chapter 7: Counseling Students with Hearing Impairment
Chapter 8: Working with Families