What truths about human health, thought and behavior lie hidden in the audiogram?

What is the audiogram profile for schizophrenia? For asthma? For a skin rash? We have the answers to some of those questions. First, you need to know how to read an audiogram.

Sound arrives from any direction, so the geographical “map” of the audiogram should be 3-dimensional and stretch into the layer of air surrounding the earth (62 miles thick) and, sometimes, beneath our feet. I have heard our house shudder and roar when the vibrations of an earthquake charged through the ground from its epicenter in Quebec to the Toronto area. The loud sound was not from the ground because the person standing a few feet away from me outside the house felt the earth shake but heard no sound. The house resonated to the earth’s vibrations. How does our body resonate to the sounds that enter the brain through the ears?

With the size of the audiogram “map” in mind, let’s look at its usual use, which is to identify “hearing loss.” Hearing loss is measured at many frequencies but is not analyzed in much detail in terms of those frequencies. If you can hear any frequency at a threshold within the “normal” range, your threshold could be as quiet as a whisper, the chirping of birds, and the rustling of leaves or as loud as conversational voices. If you cannot hear whispers, birds, and leaves and can barely hear conversation, you are edging into the “mild hearing loss” zone. The “geographical” range is from 1 cm (3/8 in) to 1,000 cm (32.8 feet or 10.6 yards). If you accept some descriptions of “normal” that start in the minus-decibel range, where a person can hear the sound of snowflakes landing, you can imagine that a person with differing thresholds for particular frequencies of sound will have trouble “mapping them together” in their personal geography, even if they have been told they have “normal” or “good” hearing. Add the facts of differences between the right and left ears in the perception of those frequencies and you have another extremely important set of variables to consider, especially if the left ear is more sensitive than the right ear that should dominate the auditory process. Most of the serious learning problems, including those labeled as “mental illness,” that originate in the ear affect people whose hearing falls within the range of normal or of slight hearing loss.

Let’s look at just one of those configurations, one that is important for understanding dyslexic syndrome. The audiogram that shows where familiar sounds fall on that grid also places the sounds of letters used to form words on that grid. They are distributed across the frequency range from 250 Hz to 6 kHz. If you can hear “a, e, i, o, and u” (all the vowels), which fall into the range of lower frequencies from 250 to 750 Hz, but have “slight hearing loss” so you cannot hear the consonants “p, h, g, k, f, s. and th,” how can you distinguish “pit, pat, and pot” from “fit, fat, and fought” or from “hit, hat, and hot”? If the “f” sounds the same as “th” you may say “fick” for “thick” and “fought” for “thought.” Someone who “lisps” usually is pronouncing what she or he is hearing and, for that person, the more sensitive ear may be the left ear, which is not optimal for making meaningful distinctions with the left-brain. If you strengthen the ear so that the person can distinguish “f” from “th,” the person will quickly learn to correct the pronunciation, especially if the dyslexic tendency is caught early in childhood so that the errors do not become too strongly reinforced.

We take for granted that people do not all see the same way. To standardize vision many wear corrective lenses in front of their eyes. It is important to know that we do not all hear sounds the same way as others, even if we can carry on a conversation or have “normal” or “good” results on an audiogram. When you learn more about dyslexic syndrome, which is a right-ear problem, although the left ear is involved, you realize a child is disadvantaged in many ways by being deprived of any frequency needed for excellent hearing.

Many readers will have seen misspelled writing that nonetheless can be read intelligibly. A similar ability of the brain applies to distortions of the sounds in words. People who experience those distortions can learn to make good guesses about the words they are hearing. Some bring lip-reading and body-language reading into their interpretive skills for the bits and pieces of language they cannot quite hear. Very little attention is paid to these sorts of differences in the way people hear until the distortions between the hearing in each ear cause the symptoms of dyslexic syndrome. However, people who “know the territory” will be able to notice significant problems on an audiogram. Guy Bérard’s Hearing Equals Behavior provides sample audiograms of “bilateral [both ears] distortions.” He identified similar hearing patterns in an autistic patient. Then, in other autistic patients. He discovered the specific audiogram profiles for depression, including suicidal depression—and he altered the hearing of almost all of those patients so their behavior changed and their audiograms reflected those changes. He recognized the points of hyperacusis at 1 kHz or 1.5 kHz or 2 kHz that indicate such allergies as asthma, hay fever, or eczema that disappeared as symptoms and vanished from the audiogram following treatment (Bérard, Hearing Equals Behavior, 42).

We are beginning to diagnose and heal so-called “mental” illness by reading an audiogram profile and treating the hearing of the patient to alter symptoms and to revise that person’s responses on the next audiogram. We are changing that person’s location in his or her audio geography. When people can hear more like one another, other commonalities in thought and behavior and health appear.

The Basics*

An audiogram is a chart currently considered by audiologists to show a person’s hearing ability. A standard set of symbols represents measurements written on the chart. While testing—and the symbols used to record tests responses—are practically universal, you need to check the key on your audiogram to be sure it fits standard use.

The horizontal axis is a scale of frequencies (pitch) measured in Hertz (Hz) or kiloHertz (kHz, also khz). The vertical axis is a scale of volume of sound or loudness measured in decibels (dB). The low frequencies on the left side start at 125 or 250Hz and usually are tested at 500-Hz or 1,000-Hz intervals up to 8,000Hz or 12,000Hz. It is not unusual for an audiologist to skip some of those frequencies, such as 3 kHz, 5 kHz or anything above 8 kHz. The decibel scale is measured against several opportunities to attempt to hear the sounds because a “threshold” of hearing means “the level of sound that a person can hear on at least 50% of the tests.” It may take a few tries at higher volumes for a person to realize he or she can “tune in” to a lower volume. Ideal testing conditions are created in a sound-proof booth. Strict testing conditions may not be available to some people. Approximate tests can be made at home through computer programs if you have headphones. As I have not been able to check them against good equipment, I am not ready to recommend them.

The scale starts at 0 dB, but that does not mean there is no sound generated by the testing equipment. It is the quietest sound a person with “normal hearing” can perceive at least 50% of the time. Some people can hear sound at -10 dB or less.

Testing done with headphones are “air” thresholds as the sound must travel through the air in the ear canal to move the ear drum. Air thresholds for right ear responses are marked with “O” and for the left ear are marked with “X.” Furthermore, the right ear may be recorded in red pen and the left ear may be recorded in blue pen.

Bone-conduction hearing is tested with a vibrator that rests on the mastoid process of the skull (behind the ear). It is held in place by a narrow metal headband. It vibrates the bones, tissues, and fluids within the skull, affecting the cochlea, which is embedded in that bone. Stimulation of the cochlea is said to occur “directly,” while largely bypassing the outer and middle ear structures. Bone-conduction thresholds for the right ear responses are marked with a < symbol and for the left ear with a > symbol.