Eartips – How They Affect IEM Sound

Anyone who has ever owned a pair of IEMs would undoubtedly have noticed that eartips are a fundamental ingredient to the product. However, many people (especially new-comers to the audio world) seem to assume that they serve a purpose no more significant than allowing the IEM to fit correctly to a person’s ear (in terms of sizing), and perhaps to add some colourful style. They’re not entirely wrong, but there really is a lot more to it than that. As the title of this article implies, these seemingly insignificant little silicone/foam pieces actually can and do play a significant role in the entire IEM experience, and in particular to how they sound.

Comfort

Of course, eartips are available in a variety of sizes, mainly because no 2 persons’ ears are the same size, and so in order to create a proper seal within the ear canal, each person would require a set of eartips that fit them well.
However, even if an eartip happens to be sized absolutely perfectly for a particular person’s ear, the eartip’s material and design will affect the sound, as well as comfort. Comfort plays a huge role in how we experience an IEM’s sound. Whilst comfort itself doesn’t have a direct impact on the sound, an uncomfortable feeling will be a constant source of distraction, and this won’t allow you to be in a comfortable mindset where you can simply sit back and enjoy the sound. The Dunu DK-3001 is a fantastic example of this.
Whilst the Dunu’s source of discomfort has to do with the design of the IEM’s body rather than the eartips used, it just goes to show that an IEM could technically be a great sounding product, but if it’s uncomfortable to wear for extended time periods, it simply won’t be as enjoyable as it should be.

IEM Design

An IEM’s design can also (to some extent) dictate what eartip is required, specifically in terms of size. This is because an IEM which has, for example, been designed to have a shallow insertion depth (into the ear canal) would require a larger eartip, as opposed to an IEM with a deeper insertion depth which would require a smaller eartip.
For this reason it’s important to remember that you might very well require different sized eartips if you plan on having a collection of IEMs.
My personal favourite eartips, for example, are the JVC Spiral Dots. But the required size really does depend entirely on how the IEM has been designed. To put this in perspective, for the ProPhile 8 I required the Small size, whereas the Pinnacle P1 called for the Medium Large size to be used. This also largely ties into the comfort of the IEM, but equally important is that the eartips are also directly responsible for the seal created within the ear canal (more on this shortly).

Material

When it comes to eartips, there are 2 types of materials used – silicone and foam. The material is an important factor to consider, as this has a direct impact on both comfort and sound. Sometimes these can even be combined to give a silicone-foam hybrid eartip (as in the case of the Symbio tips)
Comply eartips, for example, are exclusively made of a memory-type foam which aims to create a more “custom fit” type of feeling for the user, but can also be less comfortable than silicone for some people too. Also, foam does degrade over time, and so will need to be replaced at some point.
In general these eartips do tend to increase isolation between the ear canal and the outside world, and as such also tends to elevate an IEM’s bass response too. Also, because of the structure of the foam, the sound often is “dampened”, and so can sometimes come across a little “muffled”. This is by no means a set-in-stone rule, though, and so this effect will vary from eartip to eartip.
Silicone eartips, on the other hand, are far more common, and are usually the material of choice for the eartips that are included with an IEM. There also seems to be a much wider variety of after market eartips made of silicone, from the likes of JVC (Spiral Dots), Spinfit, Sony (hybrids), etc.
Usually, silicone eartips tend to offer less isolation than foam eartips. Also, silicone tends to be the more convenient eartip, as memory-type foam eartips require you to first compress the tip, then insert it into the ear canal, and then wait for it to expand. Silicone, on the other hand, just pops in. But again, this isn’t a set-in-stone rule, and as such will be influenced by a person’s preference, the eartip’s design, as well as the IEM’s design.

Check Comply Foam Products Shop on Samma3a

Eartip Design

Whilst the material used for an eartip does tie into the design, the actual shape needs to be considered as well. Over the years we’ve seen some pretty interesting designs; from the tradition single-flange designs, double-flange designs, as well as even triple-flange designs that are so popular on Etymotic‘s IEMs. These design elements all influence the fit and comfort of an IEM, the isolation (which affects sound), as well as the frequency response of the IEM.
Then there’s also the “tuning” of the eartip. In the case of silicone eartips, this comes down to how the manufacturer chooses to mix and match various thicknesses of silicone, how soft it is, as well as the bore diameter. Usually the “dome” of the eartip would be thinner than the stem. This is because you need a stiffer portion for the stem in order to keep it firmly in place on the IEM nozzle, but it also needs to have just the right amount of flexibility so that it can conform somewhat to the person’s ear canal. However, if the stem is too soft, it could collapse when inserted into the ear, which could muffle or even completely block the sound from reaching the person’s ear drum.
As mentioned, the bore diamter of the stem is also important to consider. If you’ve ever dipped your toes into the world of DIY CIEMs (custom in ear-monitors), you may very well have learned what effect the diameter and length of acoustic tubing has on the frequency response. In the case of eartips, the same rules apply for the diameter of the stem. A wider diameter will usually give you a reduction in the bass frequencies, whilst at the same time giving an extension in the upper registers. And then the inverse is true for a smaller diameter bore.
Now this is usually what we can expect to see (in terms of bore diameter), but there are a number of factors that will affect the final frequency response. In the case of the Spiral Dots, for example, we would expect to see an increase in the higher frequencies, and a reduction in the bass region due to the very large bore diameter. But instead we usually see the Spiral Dots producing a more linear frequency response by increasing sub bass and smoothing out higher frequency peaks. This is perhaps due to how well the Spiral Dots seal, and perhaps also due to the actual spiral dot design within the stem.

Isolation

For the most part, the main function of the eartips is to create a seal within the ear canal. If you have a set of IEMs, try breaking that seal even just lsightly, and you’ll be bound to quickly find out how that reduction in seal dramatically affects the sound. You’ll be left with a tinny, perhaps even shrill and bass-less sound.

However, this seal also affects how isolated the ear becomes to the outside world, as well as the perceived sound stage.
When eartips provide a good seal but still allow ambient sounds to “leak in”, the user might feel the need to increase volume as the ambient noises and the music coming out of the IEM “fight” against each other.
Let’s also consider open-back headphones for a second. Part of the appeal of an open-back headphone is how it usually portrays a wonderfully realistic sound stage, as it inherently allows ambient sounds to reach the listener’s ears too. So this idea does partly carry over into the isolation effect of eartips as well.

Overall Sound

OK, so we have fairly briefly discussed the effects that an eartip can have on the sound, but let’s look at some more objective data. Below are a few frequency response (FR) measurements of the new Fiio F9 using various eartips.

ALL CREDIT GOES TO BROOKO FOR CONDUCTING THESE TESTS AND PROVIDING THE GRAPHS.

The first image illustrates how the FR of the F9 changes between using no eartip at all, against the Crystal Foam eartips from Crystalline Audio.
Notice how the Crystal Foam eartips help to balance the overall FR by bringing up the bass region, whilst taming that awfully sharp 7kHz peak. That peak is the F9’s biggest flaw, and you can read more about it in our full review of the F9.

Next up is the FR comparison between Ostry Blue tips and Crystal Foam tips.
As we can see, both foam-type eartips have a near-identical effect on the bass region, but the Ostry lifts up the mids, whilst rather dramatically reducing the higher frequencies.

Then there’s also the ever-popular Comply eartips.
Here we see the Comply and Crystal Foam tips having a very similar effect on the F9’s FR. Its only really towards the higher frequencies that we can see any major differences. Take note especially of hoy the Comply tips influence the 7kHz spike, bringing it in much better balance to the 2.3kHz peak.

Now let’s have a look at how some silicone eartips compare against the Crystal Foam tips. First is the Sony Hybrid eartip.
 Here we see the Sony Hybrid affecting the sound in a very similar manner to how the Ostry Blue tips did. We get the same major decrease in higher frequencies, whilst not taming the 7kHz peak quite as well.

Spinfit tips are quite popular too, and are sometimes even included with higher-end IEMs
Here we saw something veyr interesting. Whilst the Spinfits affected the F9’s sound pretty much the same way the Ostry Blue and Sony Hybrid tips did, there is a significant change (reduction) in the sub-bass region.

And finally we have the JVC Spiral Dot eartips.
 Here we saw what seems to be the best-balanced FR of the lot. Whilst the overall graph does look very much like that of the Comply tips, that 7kHz peak is just tamed a bit more. Now, when we take into consideration the Spiral Dot’s very comfortable fit and how it evens out the FR, it does seem like the best tip to use with the F9 (at least as far as these measurements show).

Conclusion

So hopefully this has given you some insight into how eartips can and do affect the sound signature of an IEM. Whilst they may seem like nothing more than a part used to attach the IEM to a person’s ear, their effect is undeniable.
But of course, as with most things, no single eartip will work best every single time. Not only should we consider the fact that fit and comfort will depend very much on an individual, but how different eartips affects the sound differently will also mean that experimentation (“tip rolling”) will be needed in order to see which eartip works best for each IEM on a case by case basis.

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