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Audiograms - How to Interpret Your Hearing Test Results

When you have a hearing assessment, your hearing will be tested and an audiogram produced.


The audiogram shows the threshold of your hearing, it's a map of the quietest sounds you can hear. Mine is shown above (it's shockingly bad!).


Right is always red and blue is always left in audiology.


Frequency


From left to right is frequency (pitch) of sound, measured in Hertz (Hz) and Kilohertz (kHz or K). The left of the graph is the lowest frequency and the far right is the highest frequency we test. We test speech frequencies as these are most important, but you may be able to hear lower or higher frequencies than are shown on the audiogram.


Volume


Top to bottom on the graph is sound intensity (volume), measured in decibels (dB or dB HL). This is a different scale than 'true' decibels as it's made specifically for testing human hearing, so it won't necessarily match up with a different dB scale. The scale means that each frequency at, say, 10dB HL is perceived by humans at the same volume, even though it may be physically different in intensity.


So, at the top we have the smallest sounds, -10 or 0 would be supremely tiny! You may have been able to hear these tiny sounds when you were a child, or you may never have been capable of it, this is very individual. At the bottom we have 120dB which is an incredibly loud sound, as intense as a pneumatic drill in your hand. So this small chart encompasses everything from the gentlest sound to just below the point where it would cause you physical pain to listen to it. This massive scale of hearing is turned into a logarithmic scale so it fits sensibly onto a page, but what that means is that each increase of 10dB is roughly double the previous. So a small change in your hearing can be very impactful, and the difference between mild and moderate is actually rather large. Your audiologist is not kidding when they say you might need help with your hearing!


An arrow on your circle or cross (e.g. 8kHz on the above audiogram) means that the hearing is so poor that it couldn't be made loud enough for you to hear. So although you'll see a symbol at each frequency, it doesn't mean you can hear at each frequency. And even though I have a symbol at 100dB on my audiogram, it doesn't mean I have hearing. You won't normally see symbols above 100dB on the audiogram, even though it goes up to 120, because we don't always test as loud as the graph would indicate we can.


Normal vs Hearing Impaired


Most people with great hearing would show a flat line at around 5 or 10dB, meaning they can pick up very quiet sounds at every pitch. Any deviation from that imaginary flat line means you have a hearing loss. It means I had to make that particular pitch/frequency of sound louder during your test so you could pick it up. When I have established the quietest level you can hear at for each frequency, I mark it with a circle (right ear) or X (left ear).




Air vs Bone Conduction


The chevron shaped symbols on the left (blue) ear are bone conduction readings. They can also be displayed as [ or ]. We test your hearing by air conduction with headphones to measure the normal way you perceive sound, over the air and through the ear canal, eardrum, middle ear bones, cochlea. That is the longer of the red/blue lines.


At a smaller range of frequencies, we also test using bone conduction, where the sound is played directly to the cochlea (the spiral shaped organ that is the inner ear). This is a special headset which vibrates against the skull, vibrates the cochlea in its bony location. You'll perceive this as sound directly, without using your outer or middle ear.


By comparing bone conduction and air conduction readings, I can diagnose what type of hearing loss you have. If the chevrons and cross/circles on the audiogram are both greater than 20bB AND similar to each other, this means you have a damaged inner ear. It makes no difference how the sound gets to you, because it's the inner ear that is damaged.


So, the graph above shows a sensorineural (inner ear) hearing loss. This is the most common type of loss. A conductive loss would have the chevrons sitting higher up than the crosses, with a fair sized gap between them.


Most people will have an audiogram that slopes like this, from left to right, indicating a high frequency loss. If yours doesn't, ask the audiologist for an explanation of what you're seeing.


Level of Loss


The further down the page, the greater the level of hearing loss. We categorise this to make it easier to explain.



Where it gets confusing is that your hearing will most likely be different at different frequencies. So with my audiogram, I have a "profound hearing loss". But it's normal in the low frequencies, so I also have "normal hearing". I describe it as a severe high frequency loss to avoid confusion, but your audiologist might describe your test results differently. Take a look at this typical audiogram for someone with an age-related hearing loss, who is very likely in need of hearing aids...



It can be described as: normal to severe loss; moderate hearing loss; severe high frequency loss. All are 'correct'. The terminology is not as important as the impact, and when I see that audiogram, I see someone who will be struggling with speech. They'll be able to hold a conversation one-to-one easily enough, but if the speaker turns round or starts walking away, the person will start to miss the words. In a group setting, they'll get the gist, and will be ok with the person directly next to them, but will confuse a lot of words when people talk over each other. In a restaurant, with background noise/music, they'll likely be having to concentrate hard to focus on each speaker, and will miss what's being said around them due to focusing so hard. They will likely soon be avoiding going out for dinner, especially with quieter relatives, or they'll mentally check out of the conversation and only talk to the person on their immediate right/left (or directly opposite if the table is not too deep). When the waiter pops up behind them, they'll not hear what he says. Back at home, this person has had an increasingly frustrated spouse who has noticed them getting more and more deaf, and in the last few years they've really started to get annoyed by that TV being on so loud, and the fact they miss the parcel delivery or come up with excuses to avoid answering the phone!


Even a "mild/moderate" loss is enough to cause quite big problems in groups/noise. And when the 1kHz area starts to drop as well, the person suddenly notices their hearing is causing problems in all situations.


So, it's good to be able to interpret your audiogram, but it's not the important part of your journey. People who are reluctant to seek help will latch on to the 'mild' word when you say ' mild to moderate loss'. They will say "my audiologist says it's only the high frequencies that are affected". And you'll also hear people saying "it's normal for my age" (but not normal normal!).


People with any hearing loss should have it investigated, and have an honest appraisal of how it's impacting them and their loved ones. Once it starts impacting on your conversations, your choice of social activity, your enjoyment of activities, it needs to be attended to. That point may be mild on your audiogram or it might be severe, everyone is different and there are other factors involved in how well you hear, such as the affected frequencies, your central processing ability, the listening situation, accents or even just how tired you are.


Hearing Aids?


As an audiologist, the audiogram is one part of how I work out whether to recommend aids, but the verbal history from my patient (and often their partner) is the biggest indicator of whether they would benefit. Hearing goes so gradually that people mostly accept it as their new normal. When someone has a virus or an injury that results in a mild/moderate hearing loss practically overnight, they feel like their world has turned upside down. They are visibly upset, their work is suffering, they can't hear on the phone, they're embarrassed in shops because they can't hear the server. The same audigram where the hearing loss was acquired over 5 or more years gives you a very different patient! "I'd be ok if people didn't all mumble these days", and my personal favourite "audiologists just want your money, there's nothing wrong with me". ☺️


I provide copies of your test results along with a written recommendation as part of my testing fee. All audiologists can do this, so request a copy of your results every time you're tested, it helps your future audiologist keep track of how your hearing loss is progressing, and will help them make better recommendations.


This post was inspired by a question from a customer who wanted to know more about his audiogram. If you have any questions on hearing that you'd like answering, please submit them by email and I'll consider them for a blog article.

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