A Hearing Loss & Late Deafened Blog

Reading Your Audiogram

This was originally published as a post in June, 2008.  We’re still getting so many views, and the info is so vital to anyone who has hearing loss, I decided to create separate page.  Hope you find it helpful!

Last month I completed a project on audiograms for a class. Realizing many people with hearing loss don’t understand what all the symbols mean, I thought I’d condense it into a blog. I am not an audiologist, nor an “expert” on audiograms. I’m just a person with hearing loss, so if something doesn’t make sense, I suggest you ask your audiologist. This is just a very short, simplified overview. I’ve also included links at the bottom for further reading.

In order to understand an audiogram, first you need to understand sound. There have been entire books written about sound alone, but I’m going for simplicity here.

Why does a frog sound different from a bird? Sounds vibrate at different speeds. Low sounds vibrate more slowly than high sounds. Here’s an illustration of low frequency sound (on the bottom) vs high frequency (on top).

frequency-wavelengthPitches tested on an audiogram may range from 125 hertz to 8000 hertz. The vertical lines of the audiogram indicate pitch. 125 hertz is a low-pitched sound, while 8000 hertz is high-pitched.piano_frequency_chart

The piano above is a great way to illustrate low-pitched vs high-pitched sounds. Of course many sounds are lower than the lowest piano key. Likewise many other sounds are higher-pitched than the highest piano key. Additionally, there are pitches between each key, and so on. Audiologists do not measure every single pitch known to man; they only measure a few pitches at certain intervals to give them an idea of how you might be affected by hearing loss.

You already know some sounds are loud and some soft. A loud bus can sound soft in the distance. It becomes louder as it gets closer. It is the same sound near or far; only the intensity has changed. The loudness of a sound (intensity) is measured in decibels (dbs). Below, the horizontal lines of the audiogram represent the loudness of sounds (decibel intensity).

audiogram sound intensityThis makes perfect sense if you think about it. When you turn the volume up on your CD player, the pitch of the music you’re listening to stays the same. You recognize a piece of music whether the volume is high or low, unless it’s too low to hear.  Intensity levels measured on audiograms range from about 5 dbs (very soft) up to 110 or 120dbs (very loud).


Putting it all together, your audiogram may look like this if you have good hearing:

audionm1 good hearing
Everything above the blue and red lines (the hearing threshold) is what you don’t hear in each ear. Everything below the lines is what you hear. The audiogram above represents good hearing because the hearing threshold falls at or above 10dbs in all the pitches tested.


Now let’s look at the “speech banana.” Most speech sounds fall in a banana shaped area of the audiogram called the speech banana.  

speech banana chartMisunderstanding speech is what sends many of us to the doctor when we first begin losing our hearing. As you can see, some sounds like ‘th’ and ‘s’ fall in the high pitch ranges, while other sounds like ‘m’ and u’ fall in the low pitch areas.  Many people have significant hearing loss in some pitches while their hearing remains good in other pitches.   Depending on your hearing loss, you may have difficulties hearing high pitched sounds or low pitched sounds.   The speech sounds you hear well may drown out the speech sounds you don’t hear.   This is why, when we lose our hearing, we may feel like we hear a lot of sound, but there may no clarity.   We are only hearing some sounds.  This is also why it seems to others that we can “hear when we want to hear.”  We can literally hear better sometimes.  Depending on what is said, there will be more or less blanks to fill in.  

Some people place the number of English phonemes at around 40, however others say it’s impossible to know how many phonemes there are because of all the different English dialects. Additionally, some people speak a blend of English dialects. Your hearing threshold and exposure to various dialects can impact understanding when you have hearing loss. Also, when you lost your hearing– if you lost hearing pre-lingually as opposed to post-lingually– makes a difference.

Further, individuals all differ in speech comprehension. Two people with the exact same hearing thresholds may not hear exactly the same way. This can be hard for some to understand, but think about runners. All feet are different. Some people have flat feet, some don’t, some people are bow-legged, some may have scar tissue from old injuries, some legs are short and others long. Many factors determine how fast you run. It’s the same with hearing. Many factors determine how well you understand the sounds you hear besides measurements plotted on your audiogram. There are differences in how all your parts work together, as well as voices you’re used to and dialects, and many other variables.

As I mentioned above, when people lose their hearing they don’t necessarily lose all their pitches equally. A common type of hearing loss is the “ski-slope” where low tones remain intact, while high tones drop. There is also a reverse ski-slope, a “cookie bite” and reverse cookie bite.

Why does this happen? If you look at the picture of the cochlea below, you will notice different areas of the cochlea are responsible for detecting different frequencies.

Cochlea_freqOften the nerves in only one area of the cochlea are damaged, while other nerves remain healthy. A similar analogy would be experiencing numbness in just one part of your leg after having a bad accident.


During sickness, parts of the cochlea may become damaged. Those parts may not react to sound unless amplified. When a hearing loss becomes severe to profound, amplification may no longer do the job adequately. A person can begin to experience pain with loud amplification while simultaneously unable to hear– especially when other parts of the cochlea still work just fine. The cochlea has become dysfunctional.

Below is an example of the common ski-slope hearing loss. The slope can be steeper or less steep. Notice the severe hearing loss at 4000 hertz, but “normal” hearing at 1000 hertz. Without hearing aids, this person will hear ‘m’ and ‘u’, but not ‘f’ or ‘s’. Listening to speech becomes a constant game of fill-in-the-blanks.


hears_to_life_188754_scan0001What do the x’s and o’s mean??

The circles indicate measurements for the right ear.

The x’s indicate measurements for the left ear.

What are the brackets on an audiogram? While the “air conduction” test determines hearing threshold (the blue line below), audiologists also perform a bone conduction test, with a vibrator placed near the cochlea. This can help the audiologist determine whether there’s a problem with the cochlea or some other part of the ear. The brackets indicate the results of the bone conduction. They usually look like this > but sometimes they look like this ].

 

Below there’s a disparity between the bone conduction and air conduction results. The cochlea seems to be working fine, as shown by the brackets. In this case, doctors determined it was due to infection of the middle ear.

conductive hearing loss

For Further Reading:

http://www.hearingresearch.org/Dr.Ross/Audiogram/Audiogram.htm

http://www.audiologyawareness.com/

http://www.drmehr.org/audiograms.html

http://www.earinfo.com/how-to-read

Pictures:

1) http://sciencedoing.blogspot.com/2012/10/sound-frequency.html

2) http://en.audiofanzine.com/dossiers_v3/making_a_studio/part2/piano_frequency_chart.jpg

3) http://www.sd47.bc.ca/auditoryoutreach/teachers/PublishingImages/audiogram.JPG

4) http://american-hearing.org/images/audionm1.gif

5) http://urbanomnibus.net/redux/wp-content/uploads/2012/10/stillspotting_bronx_chart.jpg

6) http://odonnell-wiki.cs.uchicago.edu/images/c/cc/Cochlea_freq.jpg

7) http://2.bp.blogspot.com/_waf4e8nPXCM/TCJR6pdbJCI/AAAAAAAAAAM/QIpUHLxZHs8/s1600/hears_to_life_188754_scan0001.jpg

8) http://audiologyawareness.com/hearinfo_agconduct.asp

 

 

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  1. Wow! So that’s what it all means. I’ve been taking hearing tests since childhood. (Bleh!) Now I can go back and look at all the grids and see the changes and what they mean. My grid lines are now in 60 to 100. Not a good sign. But at least I’d be able to prove and explain to my family – I am not ignoring you, I have hearing loss.

  2. Beautiful explanation!! Love this!

  3. This explanation is excellent.
    I wrote an article for our blog a few weeks ago about audiograms and hearing aids. I’m not sure how relevent it is to readers of this site, but thought I would share the link anyway.
    http://www.australiahears.com.au/Blog/tabid/78/entryid/25/hearing-loss-audiogram.aspx

  4. I’ve had ongoing problems with fluctuations with my hearing for almost a year. I found your explanation quite helpful. You may want to pop by my blog to read of my experiences (starting Jan 2010) and what efforts I have made to determine what is wrong. It has been a year long project!

  5. Great post
    Thank you

  6. Found this page by chance – finally understand what our daughters world sounds like!

    • Amen, my child is now 10 years old. However he was born with a disease that wasn’t caught at birth nor by any doctor. Finally when I caught him reading my lips at the age of 8( this is after repeating kindergarten 2x and then struggling in 1st grade in only reading. He had faked it until he made it. Bless this baby’s heart and soul. I feel his pain and if I could give him my hearing I would. No way for him to have h aids due to the disease eroded all canals, bones, etc. we are fixing to have surgery number 10. I am at a whits end and need all prayers I can get. It just won’t stop. There is no cure for said disease, nor not much research either. Why not? No clue?
      My question is why is my child being denied disability? (IT STATES BC OF MY INCOME). Well please forgive me I work and am not one that can sit on rear end all day. I am a single mother of 2 children. I bust my rear everyday to provide. But what does money have to do with a disability? Please help? Stuck in shock and confusion in state of MS.

  7. This is interesting and I’ll re-read it a bunch so I’ll better understand it.

    I’ve studied physics at the university level (I’m a retired meteorologist), but my progressive hearing loss in my 50s and now my 60s has given me a greater appreciation for how sound behaves. Such as that high pitches are much less omni-directional than low pitches, and that high pitches don’t go around corners so well. That’s the reason it doesn’t matter where, with a subwoofer speaker system, the woofer is placed, and the little tweeters need to be wall-mounted pointing toward the listeners.

    Thanks for this article. I have not had a professional hearing test yet (where I currently live, medical services are very limited but we’re moving soon), and have only played with a couple of online tone generators. Playing with one of those, I noted that above 4KHz my hearing fell off sharply, and was practically nil above 6KHz. My wife, who has perfect hearing in one ear and is nerve-deaf in the other ear (apparently from an ototoxic medication she was given during a health crisis on which various drugs were thrown at her in the effort to save her life) yelled from the opposite end of the house “What the HELL are you doing?!”. That’s when I first realized how bad my hearing had become.

  8. There is growing evidence that the most accurate test of hearing is self report. See the recent Finnish study. I have never been sure why we need to use audiograms as a basis for correcting difficulties.

  9. This is really a helpful post and easily understandable on the topic of audiogram. Your post is spreading the awareness about the hearing test and also help people in understanding the result shown after hearing test. Thanks and keep sharing.

  10. Excellent article! Thanks! My hearing loss is, I assume, age-related… not what I’d call “profound”, but bothersome and gradually getting worse. My impairment is in the high range… practically deaf above about 4000 Hz. In the process of a major geographical move, and once moved, will seek out an audiologist in new community (health service are limited where I currently am).

  11. Thank you for posting this information. I’ve had hereditary and gradual hearing loss, as have my family on one side as far back as the late 1700s (and recorded by hearsay back to the mid 1600s). Some of it is nerve deafness, and most times it’s high frequency, though sometimes it “flips” to low frequency. I suffer from a gradually worsening CAPD, which makes any sort of background noise cause me to be completely unable to process any noises except those that are extremely different… I can’t even hear inside my own head when it’s noisy. I expect to be shopping for something that can help me sort sounds, even if all I could get would be a directional microphone and hearing aids.

    Now my daughter is suffering some hearing issues, and I was searching for a “normal” audoigraph in order to see what loss there was. Thank you for explaining these so well. Now I know that she, too, is likely to manifest some other issues along with initial loss. It seems to be located primarily in the inner ear, as the membrane tests were beautifully reactive, yet she cannot hear in some ranges very well, and has some APD evidence.

    I’m also taking the step of learning Sign as soon as I can find a good class. I will teach my father and daughter, and any other family who wishes to learn.

  12. Well done! I appreciate the explanations. I have hearing loss in upper range, What is correlation between that and background noise making it nearly impossible to hear. Also how much does Lip reading skills help, maybe I need to do that?

    • My hearing is at 45 db all the way across and has been all my life, I even produced 2 deaf little boys. The reason I shared this is so you understand where I’m coming from. The way i was taught was that the brain is what figure’s out what your hearing, the inner ear just ships it to the brain. But, if the inner ear is getting muddled signals, so it the brain. Think of it as a puzzle missing pieces, you can’t put it together so you have to guess at what the picture is by using your memory of other puzzles. If there is no other puzzles to go by you give up and quit, the brain is the same way. Does this help?
      Yes reading lips helps a lot! I’ve done it since I was little, but, you can learn it. If I was having to learn it now, I would turn off my hearing somehow like cotton ball or ear plugs and just dive in.

    • lip reading helps a lot! It really makes a difference!

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  16. […] period of time, and with higher regularity of use. This study concluded that men with steeper audiogram slopes (those with discrepancy in hearing low pitches versus high pitches) were less likely to use their […]

  17. This article explains so well, thank you.

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