What is an Audiogram and How Should I Read It?

Have you ever visited an audiologist or a hearing care expert for a professional hearing test? If yes, you must be aware of the drill. After doing a quick inspection of your ears, the hearing care expert will request you to wear headphones in relatively quieter settings and play beep like sounds of varying frequencies in each ear, one after another. If you are able to catch the sound, you will nod or raise your hand. The pitch of the sound keeps getting higher until you are unable to hear anything. The results of this exercise are used to create an audiogram, which is basically a two-dimensional plot illustrating the relationship between the volume (in decibels) and frequency of the sound (in hertz).

Overview of an Audiogram

An audiogram is essentially a graph showing a series of O’s (for right ear) and X’s (for left ear). The graph consists of values for different frequencies on the X-axis and volumes on the Y-axis. As you move from left to right on the chart, the frequencies increase from low-pitched to high pitched, while running from top to bottom, the volume of the sound amplifies. The position of O’s and X’s indicate the softest sounds heard by varying the frequencies. This is known as one’s hearing threshold. 

How to Read an Audiogram

The O’s and X’s on an audiogram indicate the threshold for a specific frequency. If the symbol is marked lower on the chart, it implies that the person is suffering from a greater degree of hearing loss at the given frequency. This essentially means that one needs a more amplified sound in order to normally hear it at a specific frequency. 

Different degrees of hearing loss are categorized as mild, moderate, severe and profound. Usually, people face difficulties in hearing high-pitched or high-frequency sounds, such as chirping of a bird, voices of females and certain alphabets. Vowel sounds (A, E, I, O, U) are lower frequency sounds, whereas certain consonant sounds have higher frequency, including F, K, TH and S. People affected by hearing loss are usually unable to hear these consonant sounds and have trouble discerning words, such as ‘cat’, ‘show’, ‘throw’ and so on. 

Various measures calculated using an audiogram:

1. Speech Reception Threshold (SRT): It is the minimum hearing level for speech, discerned by a person 50% of the time. 
2. Speech Discrimination: It is the percentage of single syllabic words recognized and reiterated by the patient at suprathreshold levels. (usually 30 dB above SRT)
3. Word Recognition Score: It is the percentage of words identified by the patient at the hearing threshold.
4. Acoustic Reflex: It measures the level of muscle contraction in a patient’s middle ear when subjected to stimulus of high intensities.
5. Tympanometry: The measure evaluates the movement of one’s eardrum (tympanic membrane) with respect to air pressure.

• Type A: Normal
• Type B: Limited Mobility / Potential damage
• Type C: Negative Pressure

Severity of Hearing Loss 

Patients are often curious about the ‘percentage’ of their hearing loss. However, there is no specific formula that can convert the logarithmic dB values to a meaningful hearing loss percentage. Normal hearing range is defined as hearing threshold of -10 to 15 decibels at all frequencies. Given below are the definitions pertaining to various degrees of hearing loss experienced by patients:

1. Slight Hearing Loss: Hearing threshold in the range of 20 to 25 dB.
2. Mild Hearing Loss: Hearing threshold in the range of 26 to 40 dB.
3. Moderate Hearing Loss: Hearing threshold in the range of 40-55 dB.
4. Moderately-severe Hearing Loss: Hearing threshold in the range of 56-70 dB.
5. Severe Hearing Loss: Hearing threshold in the range of 71-90 dB.
6. Profound Hearing Loss: Hearing threshold above 90 dB.

About Online Hearing Tests

The internet is replete with free online hearing tests which promise to provide a thorough examination of one’s hearing abilities. However, they can only help you gauge slightly into your hearing health, and are not a substitute of professional hearing tests run by audiologists or hearing care specialists. In order to get your condition diagnosed and treated properly, you need to see a professional who would not only run detailed hearing tests, but also perform a physical assessment of the ear canal. In some cases, hearing loss is reversible, and can be cured easily, like in the case of excessive build-up of earwax. The earwax might be the only reason for the inaccurate results you might obtain from an online hearing evaluation. Therefore, before coming to any conclusion, it is important that you visit a local audiologist and request for a thorough hearing examination. 

Bottom Line

Audiogram can act as a very useful tool for accessing your degree of hearing loss. The graph represents the hearing thresholds wherein you can hear sounds at the lowest possible intensity. If the symbols of O’s and X’s are in the top end of the chart, you don’t need to worry as you are not likely to experience any major hearing issues. However, if the curves shift significantly to the lower end, it could be an indication of hearing loss. An audiogram helps your hearing doctor gain a better understanding and insight into the specific type of hearing loss you might be experiencing, and therefore suggest a suitable treatment option based on the severity of the disorder. In fact, many hearing care experts suggest a custom-tailored hearing aid only after going through an audiogram, so that your specific needs are met. In addition, the type of hearing aid which would be suitable for you also depend on your lifestyle, such as whether you stay mostly indoors or spend a lot of time in a noisy environment. 

Hearing loss can bring significant amount of distress in your day-to-day life. Getting a hearing aid installed after undergoing a detailed evaluation is imperative. Hearing experts or audiologists do just that by identifying the level of damage through the use of an audiogram. However, it is important to remember that hearing aids can only enhance the intensity of sounds, and not completely reverse hearing loss or perfectly restore your hearing capacity. Therefore, you need to be patient with yourself, and continue to focus on improving your hearing ability with every passing day.