Dayton Ear, Nose
& Throat Surgeons, Inc.

John H. Boyles Jr., M.D.         James J. Howard, M.D.         William E. Rogers, M.D.

Home

The Doctors

The Doctors Hearing Service

Services

Allergy

Allergy & Environmental Medicine Articles

Forms

Reference Links

Testimonials

Contact Us, Hours
& Directions

The Audiogram

Hearing healthcare professionals categorize hearing losses in ranges designated by common terms:

  • Minimal (Borderline): 16 to 25 dB
  • Mild: 26 to 40 dB
  • Moderate: 41 to 55 dB
  • Moderate to Severe: 56 to 76 dB
  • Severe: 71 to 90 dB
  • Profound: 90dB +

In hearing evaluations, loudness and clarity of sound signals are reflected by numbers in two different scales, hertz (Hz) and decibel (dB).

The Hz scale measures the different pitches of sound the human ear can hear, a range from 50 Hz to 25,000 Hz. Pictographs on the chart show the range of some common sounds. Hearing tests are usually limited to sounds between 250 Hz and 8000 Hz, the range of speech understanding.

SPEECH DISCRIMINATION SCORES
Correct Ability To Understand Speech:

  • 100%-90% Excellent
  • 89%-80% Good
  • 79%-70% Fair
  • 69%-60% Poor
  • 59%-50% Markedly reduced

The dB scale measures loudness or softness of a certain pitch and is recorded in 10 dB increments. For every 10 dB increase in volume, the sounds’ intensity has doubled. Between 0 dB (an average of the faintest sound heard) and 140 dB (the pain threshold), there is a 10,0000,000-fold range of sound changes. Letters show the Hz and dB levels where individual speech sounds are heard. For example, the M sound occurs at about 500 Hz and 35 dB of loudness. When a person loses hearing over time (usually about 1 dB per year due to the noisy world we live in), the hearing loss is not equal across all pitches or Hz.

Degree Of Hearing Loss

Based on pure tone testing the audiologist also will determine the degree of hearing loss. Hearing loss may be classified as mild, moderate, moderately-severe, severe, or profound. These terms have precise, technical definitions for audiologists, but frequently are used by hard of hearing people in a less technical way that may not convey a clear meaning. In the same way, a statement of extent of hearing loss expressed in percentages does not have clear meaning from an audiological perspective (e.g., “I have a 70 percent loss in my left ear”). Instead, it is important to know the degree of hearing loss that occurs over the range of frequencies tested as well as the individual’s ability to understand speech with and without a hearing aid.

The following classification system is used to describe the severity of hearing loss. It is based on the average (mean) degree of hearing loss for the speech frequencies, 500 Hz., 1000 Hz., and 2000 Hz., because most of the speech sounds in the English language fall within this frequency range.

Normal hearing: (- 10 dB to 25 dB)—Hearing sensitivity within normal limits. No effect on communication ability.

Mild: (26 dB to 40 dB)—Conversation must be loud in order to be understood; problems in group situations and other difficult listening situations. Clients may need to rely on amplification.

Moderately-severe: (56 dB to 70 dB)—Will have a great deal of difficulty understanding normal conversational speech; will need to rely on amplification.

Severe: (70 dB to 90 dB)—Will not hear conversational speech; may be able to identify environmental sounds; great reliance on visual cues and amplification.

Profound: (<90 dB)—May hear some loud sounds, but will be more aware of vibration; may rely on alternate mode of communication such as sign language. Amplification may assist in speechreading, monitoring one’s own voice and increasing awareness of environmental sounds.

Speech Testing

Pure tone testing provides information about the specific frequencies affected by the hearing loss. Although this information is valuable in diagnosing the type and degree of hearing loss, it is important to understand speech under different listening conditions. In a routine audiological evaluation the audiologist will conduct several tests to assess speech understanding ability.

One test referred to as the speech reception threshold (SRT) evaluates the lowest (dB) or softest intensity level at which the individual can identify two syllable words called spondees (i.e., baseball, cowboy) with 50 percent accuracy. In addition, the audiologist will conduct additional tests to evaluate how well the individual understands words when they are presented at a comfortable listening level. This is referred to as speech discrimination or word recognition testing.

During speech discrimination testing the audiologist typically will present monosyllabic words in a quiet environment. However, to gain more insight into how well an individual understands speech in conditions that are similar to everyday situations, monosyllabic words may be presented in the presence of competing noise, cafeteria noise, or multi-speaker babble. The presentation of speech in competing noise is a more realistic approximation of typical communication functioning.

The discrimination score is a representation of how well an individual will do with hearing aids. Those with good or excellent scores are expected to do extremely well with hearing aids and will hear very much like an individual who has normal hearing. Individuals with poor discrimination scores are expected to still have some difficulties even with hearing aids. However, their ability to understand conversation with hearing aids is expected to be much better than without hearing aids.

Speech Discrimination Scores

Correct interpretation: