The occlusion effect is the boost in low-frequency sound you hear when something blocks your ear canal, making your own voice sound unnaturally loud, hollow, or boomy. You’ve experienced it if you’ve ever plugged your ears and noticed that chewing, talking, or even walking suddenly sounds amplified inside your head. For hearing aid wearers, it’s one of the most common complaints and a frequent reason people stop wearing their devices.
Why Blocking the Ear Canal Changes What You Hear
Your ear canal is lined with soft tissue and cartilage along its outer two-thirds, transitioning to bone deeper inside. When the canal is open, vibrations from your jaw, vocal cords, and footsteps pass through these soft walls, generate tiny air pressure waves inside the canal, and simply escape out the opening. You never notice them because they dissipate before reaching your eardrum with any real force.
When something seals the canal (an earplug, earbud, hearing aid, or even a finger), those same vibrations still enter through the canal walls, but now the air pressure has nowhere to go. The trapped sound energy builds up, drives the eardrum from the outside, and adds to the vibrations already reaching your inner ear through the skull. The result is a significant boost in perceived loudness, concentrated almost entirely in the low frequencies. The softer, more flexible cartilaginous portion of the canal wall is the main contributor: it vibrates more readily than bone, pushing more energy into the sealed space.
How Much Louder Things Actually Get
The numbers are surprisingly large. A fully sealed ear canal can produce an occlusion effect of 20 dB or more at 100 Hz, which is roughly the pitch range of a male speaking voice. At very low frequencies, below about 40 Hz, the effect reaches a plateau around 40 dB. In some individual cases, researchers have measured boosts as high as 50 dB below 20 Hz. To put that in perspective, a 20 dB increase means sound perceived as roughly four times louder, and 40 dB is closer to a hundredfold increase in sound intensity.
The effect drops off sharply as frequency rises. Above about 500 Hz, it’s minimal. This is why the occlusion effect distorts the quality of your voice rather than simply making everything louder: it selectively amplifies the deep, resonant components while leaving higher-pitched sounds relatively untouched. The result is that “talking in a barrel” sensation that hearing aid users describe so consistently.
What It Feels Like
People experiencing the occlusion effect typically describe some combination of the following: their own voice sounds hollow, echoey, or boomy. Chewing becomes distractingly loud. Footsteps thud inside the head. The ears feel clogged or pressured, even when there’s no actual congestion. Some people say their voice sounds distorted, as if they’re speaking through a tube.
For hearing aid wearers, the experience is particularly frustrating because they’re already adjusting to amplified sound. Hearing your own voice at an exaggerated volume, with an unnatural bass-heavy quality, can make conversation feel exhausting. This is especially true with new hearing aids equipped with closed eartips or snug earmolds, and it’s a significant reason some users abandon their devices in the first weeks.
The Bing Test: A Quick Clinical Check
Audiologists use a simple test called the Bing test to check for the occlusion effect, and it doubles as a way to identify certain types of hearing loss. A vibrating tuning fork is placed on the bone behind your ear, and you’re asked whether the sound gets louder when the audiologist presses a finger over your ear canal opening to seal it. If you hear a clear increase in loudness, the occlusion effect is present, which indicates your middle ear is conducting sound normally. If sealing the canal makes no difference, it suggests a conductive hearing problem is already interfering with how sound travels through that pathway.
How Hearing Aid Design Reduces the Problem
The most straightforward fix is preventing the seal in the first place. Open-fit hearing aids use a thin tube or receiver that sits in the ear canal without blocking it, allowing trapped sound pressure to escape naturally. This works well for people with mild to moderate high-frequency hearing loss, since those users don’t need much low-frequency amplification and can afford to let bass sounds leak out.
When a more sealed fit is necessary (for greater hearing loss requiring stronger amplification across all frequencies), venting is the primary tool. A vent is simply a hole drilled through the earmold or dome that lets some air pressure escape. Each additional millimeter of vent diameter reduces the occlusion effect by about 4 dB. A 2 mm vent is generally considered a solid starting point for addressing the problem. Fully eliminating the occlusion effect can require vent diameters up to 5 mm, depending on the length of the vent channel. The tradeoff is that larger vents also let amplified low-frequency sound leak out, which can reduce the benefit of the hearing aid for people who need that bass boost.
As a general guideline, people with hearing loss between 20 and 30 dB benefit from vents of 3 mm or wider. For every additional 10 dB of hearing loss beyond that, the vent diameter is typically reduced by 0.5 mm to retain enough amplification.
Deep Canal Fittings
A different approach targets where in the ear canal the hearing aid sits. The outer portion of the canal, lined with cartilage and soft tissue, is the primary source of the vibrations that cause the occlusion effect. The deeper, bony portion of the canal is much more rigid and contributes far less vibration. A landmark 1988 study showed that fitting a hearing aid deep enough to contact the bony canal significantly reduced the occlusion effect. Later work confirmed that a modified deep-canal design, which minimized contact with the cartilaginous section while anchoring in the bony canal, not only reduced occlusion complaints in the majority of users but also improved high-frequency sound delivery.
Deep canal fittings aren’t suitable for everyone. The bony portion of the canal is sensitive, and not all ear canals are shaped to accommodate a device seated that deeply. But for candidates with the right anatomy, it remains one of the most effective physical solutions.
Active Noise Cancellation for Occlusion
Modern hearing aids are beginning to tackle the occlusion effect with digital signal processing rather than physical design alone. The concept borrows from active noise cancellation: a microphone inside the hearing aid detects the low-frequency buildup in the sealed canal, and the device generates a counter-signal to cancel it out. Both fixed and adaptive feedback systems have been developed, along with newer feedforward designs that predict the occlusion signal and cancel it before the wearer perceives it. These systems are particularly promising for people who need a tightly sealed fit and can’t rely on venting alone.
Beyond Hearing Aids: Earplugs, Earbuds, and Stethoscopes
The occlusion effect isn’t limited to hearing aids. Anyone using foam earplugs at a construction site or concert will notice their voice booming inside their head. Musicians wearing in-ear monitors deal with it constantly, as it changes how they perceive their own singing or playing. Even stethoscope earpieces create a mild version of the effect.
For earplug and earbud users, the solutions parallel those in hearing aids. Vented earplugs (sometimes marketed as “musician’s earplugs”) include a small channel that relieves pressure buildup while still attenuating outside noise. Some premium earbuds use open-back or semi-open designs that reduce the seal. And simply inserting a standard earplug less deeply, so it doesn’t fully occlude the canal, can lessen the effect, though it also reduces noise protection.