science

Occlusion effect

Occlusion effect is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Occlusion effect rather than just read about it. In short: The occlusion effect occurs when an object fills the outer portion of a person's ear canal, causing that person to perceive echo-like "hollow" or "booming" sounds generated from their voice, chewing, footsteps, or any other sounds originating in their own body. The bone-conducted sound travels to the cochlea through different pathways.

Key takeaways

Occlusion effect belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Occlusion effect to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Occlusion effect from memory before moving on to harder problems.

Reference excerpt

The occlusion effect occurs when an object fills the outer portion of a person's ear canal, causing that person to perceive echo-like "hollow" or "booming" sounds generated from their voice, chewing, footsteps, or any other sounds originating in their own body. The bone-conducted sound travels to the cochlea through different pathways. The outer ear pathway corresponds to the sound pressure generated in the ear canal cavity due to the vibration of the ear canal wall, which constitutes the source of the occlusion effect. At low frequencies, the outer ear pathway is negligible when the ear canal is open but dominates when the ear canal is occluded. The occlusion effect is thus objectively characterized by an acoustic pressure increase in the occluded ear canal at low frequencies and which can be measured with a probe-tube microphone. Considering that the vibrating ear canal wall acts as an ideal source of volume velocity (also known as volumetric flow rate), the occlusion device increases the “opposition” of the ear canal cavity to the volume velocity imposed by its wall and thus increases the amplitude of the acoustic pressure that is generated in reaction, leading to the occlusion effect. The acoustic impedance of the ear canal cavity represents its “opposition” to the volume velocity transfer and governs its reaction in terms of acoustic pressure. In other words, the occlusion effect is mainly caused by the increase of the acoustic impedance of the ear canal cavity when it is occluded. A person with normal hearing can experience the occlusion effect by sticking their fingers into their ears and talking. Otherwise, this effect is often experienced by hearing aid users who only have mild to moderate high-frequency hearing loss but use hearing aids which block the entire ear canal. The occlusion effect is also deemed to be a notable source of discomfort to workers wearing shallowly inserted passive occlusion devices such as earplugs. Active occlusion algorithms are needed to adequately help people with severe hearing loss. If a person suffers from "near-normal low-frequency hearing and mild to moderate hearing loss of up to 70 dB at mid and high frequencies," hearing aids with increased vent size or hollow ear-molds/domes are more suitable for them in lessening the extent of the occlusion effect. In the latter case, the open-fitting decreases the ear canal acoustic impedance and thus lessens the occlusion effect. For earplug users, an incomplete seal has a similar effect at frequencies lower than the Helmholtz resonance formed by the system (with the neck of the resonator corresponding to the incomplete seal at the interface of the earplug and ear canal wall, and the resonator cavity being the partially occluded ear canal). In general, deep-fitting reduces the occlusion effect because the volume velocity imposed by the ear canal wall to the occluded ear canal cavity decreases since the surface as well as the vibration amplitude of the remaining ear canal wall diminish with the insertion depth.

See also Lombard effect Seashell resonance

References

Worked examples

Example 1 — a first encounter with Occlusion effect

Start with the simplest possible case. Write down what Occlusion effect claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Occlusion effect before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Occlusion effect ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Occlusion effect

In research: Occlusion effect appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Occlusion effect in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Occlusion effect is common in secondary-school and first-year university syllabi. It links to neighbouring topics Audiology, Otology, so understanding it makes those chapters shorter.
In everyday life: Look for Occlusion effect outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Occlusion effect in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Occlusion effect means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Occlusion effect out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Occlusion effect in simple terms?

Why does Occlusion effect matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Occlusion effect?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Occlusion effect.