Isolation Versus Venting || The New Debate for In-Ear Design

Balvinder Singh, Chief Engineer for Stealth Sonics, discusses the benefits of a pressure release valve for in-ear monitors.

This article is Authorized by the In-Ear Monitor International Trade Organziation

Members from the In-Ear Monitor International Trade Organization share their industry knowledge about the best ways to use in-ear monitors.


February 3, 2020

Some in-ear monitor manufacturers have included venting systems into their IEM designs during the last few years. From the ADEL system, to 64 Audio's APEX  system, to Stealth Sonics' Klarity Valve™, there are now different options for end-users and different processes for manufacturers. We spoke with Balvinder Singh, Chief Engineer for Stealth Sonics, to learn more.


Isolation has been the holy grail for musicians, audio professionals, and audiophiles as they seek  the ideal IEM. However, if protecting your hearing over the medium to long-term is as important to you as it is for us at Stealth Sonics, then we need to throw isolation + venting into the mix. As a company with over 10 years of heritage in the audiology world, we understand and can’t preach enough about the importance of having proper hearing protection especially in an increasingly noisier world. Having good isolating IEMs help in that regard but that is not enough for the long-term if you need to remove them every 3 to 4 hours because you feel congested in the ears. That’s where venting and our background in audiology comes in useful.

All our IEMs — and we mean every single one —comes with our built-in one-way pressure release valve. Our one-way pressure release valve, known as the Klarity Valve™ is in the IEM shell. We decided to include the Klarity Valve™ to reduce user discomfort and fatigue, especially in scenarios where the user is experiencing changes in air pressure while wearing IEMs or has to wear IEMs for extended hours.

A good example of an environment where air pressure changes rapidly is when a plane climbs or descends, leading to a pressure imbalance between the environment and your ear. Normally, the eustachian tube (a canal that connects the middle ear to the upper pharynx, or nasopharynx) controls the pressure within the middle ear, making it equal to the air pressure outside the body. However, during a plane’s ascent and descent, the eustachian tube often can’t react fast enough to equalize the pressure, which makes your ears feel ‘blocked’. This is further exacerbated if you’re wearing earphones, ear plugs, or IEMs without the Klarity Valve™as there is nowhere for the pressure to escape and the continuous tensioning of the ear drum will cause pain and discomfort.

Another good use case for having IEMs with such venting capabilities is for the hardworking audio engineer or musician who has to use IEMs for long hours. After long hours of use with IEMs or buds without such venting features, you would normally feel ear fatigue where you find the need to just take off the IEMs for a while. In extreme cases we have seen audio professionals walking into our clinics with the early symptoms of Tinnitus which is commonly associated with the ‘ringing in the ears’, and its mainly got to do with not protecting those ears enough. With IEMs with proper venting, the pressure build up in the canal and stress on the ear drum is much reduced allowing the wearer to go on for extended sessions without ear fatigue setting in as early.


As for the concern that having a vented/ported IEM will lead to a ‘loss of seal’ or ‘bleed’, the answer is NO! As the Klarity Valve™ is designed to be a one-way valve to release pressure, higher pressure always expels to lower pressure. Once the pressure in the environment and your ear have equalized, the environmental pressure will not influence what goes on within your IEMs.

Here's why this matters.

Hi-Fi — or High-Fidelity — is the reproduction of sound at the highest quality. In order to achieve this, we have to capture as much of the audio frequency range as possible in our IEMs.

Human hearing ranges from 20Hz all the way to 20,000Hz, but the way that high and low frequency sounds propagate, dissipate and penetrate are highly varied.

Low frequency sounds dissipate much more easily as compared to high frequency sounds, and thus achieving high-fidelity is mostly about controlling the loss of the low end. A great example of low frequency loss is when you play songs on your phone’s speakers out loud, you don’t hear much (or any) bass, as it has all dissipated.

To solve this, IEMs use occlusion by filling the outer portion of the listener’s ear canal, thereby creating the perfect ‘seal’. This limits the dissipation of low frequency sounds.

Since the Klarity Valve™ is one-way only, this does not affect isolation or low-end frequency reproduction.

The above article was written by Balvinder Singh, Chief Engineer for Stealth Sonics. Balvinder holds an advanced degree in Rocket Science and when he is not engineering product enhancements, he can be found fueling his percussion addiction.

IEMITO takes no stance or position on pros or cons of venting. We remain committed to always learning more and to always sharing all aspects of the conversation.


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