Air conduction hearing is the most common type of hearing whereby sound waves enter our ears and make their way to the eardrum and beyond.
Bone conduction hearing relies on the bones in your skull to pass vibrations into your inner ear.
As such, you can rely on it even if you’ve got conductive hearing loss. Another benefit is that it lets you stay aware of your surroundings. Unfortunately, even the best bone-conduction headphones have poor audio quality when compared to air conduction.
Bone-conduction headphones are becoming more common by the day, especially with athletes.
But honestly, anyone who needs to stay aware of their surroundings can benefit from them – from a cyclist who needs to hear the traffic around them to a stay-at-home parent who needs to hear what their kids are doing at all times.
But this technology won’t sit well with everyone as it is fundamentally different from the one employed in your everyday speakers and headphones.
In this manual, we will discuss how bone and air conduction function, their advantages and disadvantages, and how they contrast with each other.
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What is Air Conduction?
We don’t typically think about the mechanics of hearing, so in case you need a refresher course on ear biology, here it is:
The human ear is comprised of three distinct parts:
- The outer ear is made up of the pinna (ear shell), the external auditory canal (ear canal), and the tympanic membrane (eardrum). The function of the outer ear is to funnel sound waves into the ear canal. These sound waves vibrate the eardrum, not unlike the diaphragm of a dynamic driver.
- The middle ear is made up of ossicles and the Eustachian tube. The ossicles are three bones attached to the eardrum that vibrate with it and pass the amplified vibrations onto the inner ear. The Eustachian tube helps keep the pressure in the middle ear at an optimal level.
- The inner ear is made up of the cochlea, the vestibule, and the semicircular canals. The main function of the vestibule and the semicircular canals has to do with balance, so let’s set them aside for now.
The cochlea has got three fluid-filled canals. When these canals respond to the vibrations of the ossicles, they set in motion so-called hair cells. The movement of these hair cells causes neurotransmitters to send electrical impulses to the brain, which interprets them into sound.
To simplify it, airwaves enter through our inner ear and vibrate the eardrum, which passes the vibrations to the inner ear. The inner ear converts these vibrations into electrical signals, and then our brains decode these signals into sound.
All three parts of the ear need to function properly for air conduction to work.
This is in contrast to bone conduction, where we don’t need all three parts of the ear.
What is Bone Conduction?
Do you know how in Math class, your teacher would ask you to write out the process by which you arrived at a solution? And sometimes, your process wouldn’t make sense, but your solution would be correct.
Bone conduction is a lot like that!
When we speak, we hear our voices via air conduction. But we also hear them via bone conduction.
The vibrations caused by our vocal cords get sent through the skull directly into the inner ear. The inner ear doesn’t care how the vibrations got there. It converts them into electrical signals, passes them along to the brain, and the brain decodes them into sound.
This is why we hear our voices differently when we speak. When we listen to our voices through recordings, we only hear the air-conducted portion, which isn’t what we’re used to.
Bone conduction was discovered by Ludwig van Beethoven, the famous nearly-deaf composer. He realized he could hear his piano by attaching a rod to it and then biting on the rod while playing.
The rod would vibrate, and the vibrations would reach his inner ear through his teeth and then his skull.
It doesn’t sound like the most pleasant experience, but it works. Thankfully, contemporary bone conduction is more refined.
Currently, we distinguish between two main categories of bone conduction devices – bone conduction headphones and bone-anchored hearing systems (BAHA).
Bone Conduction Headphones
Bone conduction headphones are like regular headphones in the sense that you put them on your head and connect them to an external device to play music.
However, they use special drivers that send vibrations through your cheekbones.
These two cheekpieces, for lack of a better word, are connected via a strap that runs around the back of your head.
Bone-Anchored Hearing Systems
Bone-anchored hearing systems, or BAHA, are a special type of hearing aid.
These are not made for or meant for your average consumer. Furthermore, they often require surgical procedures to install, as instead of vibrating against your cheekbones, BAHA relies on a titanium implant that is inserted directly into the skull.
This begs the question: If BAHA uses bone conduction as a hearing aid, can you use bone conduction headphones to that same effect?
The answer is yes! In most cases, at least.
There are only three types of hearing loss. Bone conduction headphones and BAHA only work with two of them.
The three types of hearing loss are sensorineural, conductive, and mixed.
Sensorineural Hearing Loss
Sensorineural hearing loss is characterized by problems with the cochlea (inner ear) or the nerve that connects the brain and the cochlea. This is the most common type of hearing loss, and it is most often caused by noise or old age.
Unfortunately, there’s nothing we can do about the passage of time, but if you want to keep yourself safe from noise-induced hearing loss, check out this article.
In most cases, what happens here is that the outer hair cells responsible for sending electric signals to your brain die. We also want to take this opportunity to point out that noise-induced hearing loss can also occur when you listen to bone-conduction headphones at excessively loud volumes!
Anyway, since the problem with sensorineural hearing loss lies within the inner ear, it doesn’t matter how vibrations get to it.
That’s why bone conduction won’t help against sensorineural hearing loss in any way.
Conductive Hearing Loss
Conversely, conductive hearing loss is characterized by problems in the outer or middle ear. This could be caused by anything from an ear infection, a hole in the eardrum, a problem with the ossicles, or any other reason that would prevent sound waves from reaching the inner ear.
But in these cases, the inner ear works just fine. So if you rely on bone conduction, you completely bypass the problematic part.
That’s why bone conduction is an amazing solution for anyone suffering from conductive hearing loss. Obviously, BAHA would constitute a more permanent solution in this case, but a pair of bone-conduction headphones would still get the job done.
Mixed Hearing Loss
And finally, there’s mixed hearing loss. This occurs when you’ve got both sensorineural and conductive hearing loss.
In this case, bone conduction can help, but the degree to which it will help will depend on the severity of the sensorineural part of mixed hearing loss.
Bone Conduction vs. Air Conduction
So now that we know how air conduction and bone conduction both work, let’s take a look at how they stack up against each other.
Keep in mind that this comparison is aimed toward the average consumer, so it won’t take BAHA into account.
Bones serve many functions, but listening can hardly be considered one of them. You may look to the ossicles as an exception, but even they could do their job just fine if they were made of another material. If you think about it, the ossicles don’t play a role in bone conduction.
All of this is to say that, due to the inefficiency of bones to serve this purpose, you shouldn’t expect bone conduction headphones to offer audio quality that’s nearly comparable to that of regular headphones.
Sure some models offer better audio quality than others, but even the best of them can barely measure up to the audio quality found in entry-level in-ear headphones.
You can use them for music listening, but they are at their best when listening to podcasts.
One of the main benefits of using bone-conduction headphones for athletes is the ambient awareness they provide.
However, you may need to reconsider their use in silent areas as they have audible noise escape.
Fit and Comfort
Generally speaking, you shouldn’t ever have a problem with bone conduction headphones not fitting well.
Unlike in-ear models, where you may not have appropriate ear tips or over-ear models that can lead to ear sweating or irritation, bone conduction headphones rest on your cheekbones.
The phrase “you will forget you’re even wearing them” is often used when discussing headphones, and in this case it is literally true.
At least while they’re not playing, remember, these cheekpieces have to vibrate against your cheekbones.
At moderate volumes, these vibrations shouldn’t be noticeable, but the higher the volume goes, the more noticeable and irritating the vibrations get.
Needless to say, the better the model, the less noticeable these downsides will be. Follow the link to find out which are the best bone-conduction headphones.
Which Is Better For You?
When deciding which type of sound conduction is better for you, you should always start with this question: What will you be using the headphones for?
Air conduction headphones are better for music listening and isolating yourself from the outside world. And even if you want the audio quality without the isolation, open-back headphones can do that.
Bone conduction headphones are unparalleled in staying alert to your environment, but the sound quality is below average at most.
Bone conduction headphones are also incredible if you suffer from conductive hearing loss, but for a more permanent fix, you should always consult a specialist.