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Etymotic Research ER Series Earplugs

Furthermore, I am not solely cooped up in a studio with constant measure of control over my SPL exposure (and neither are most of you). Whether it’s live FOH mixing, mixing monitors, performing in a band or simply attending clubs and concerts (I do all of the above regularly), I am constantly exposed to long-term SPL levels of 95 dB and up. That’s enough to cause long-term hearing damage and tinnitus after extended exposure.

Typical earplugs can provide 15 to 20 dB of attenuation, which is usually enough quieting for all but the loudest sources, but the lack of high-frequency response is acceptable to civilians only; musicians and audio engineers need similar attenuation, but flatter frequency response. This is where I believe the ER Series is without match, and I have found it to be a reasonable solution for all of the above environmental risks.


The ER Series “Musician’s Earplugs” filters are available at three levels of attenuation: -9, -15 and -25 dB. These filters are paired with custom silicon ear molds that are fitted by your local audiologist, formed by Etymotic Research, and then delivered with countersunk depressions to contain the interchangeable filter buttons. The -15 dB filter (ER-15) provides the flattest frequency response, with a slight drop-off beginning at 3 kHz and a substantial roll-off starting at 8 kHz. The -9 dB model (ER-9) is similar in response, with overall less high-end and a roll-off that is more pronounced and the -25 dB model (ER-25) clearly has the least “flatness” with a dramatic high-end drop-off, except for a little peak at 6 kHz. The filters are available in five colors, including beige and brown skin-matching tones.

Here’s how they work: “Musician’s Earplugs buttons have a diaphragm which functions as an acoustic compliance, while the volume of air in the sound bore of the custom ear mold acts as an acoustic mass. The combination of the two produces a resonance at approximately 2,700 Hz (as in the normal ear), which results in smooth, flat attenuation.”

The molds are as important as the filters; a tight fit, minimal leakage, deep insertion and long-term comfort are all absolute necessities for specified performance. The new silicon molds (older models used a vinyl composite) are excellent; they make a very good product even better. Silicon offers a softer feel for comfort, snugness and a clear appearance that is nearly invisible (especially with skin-matching filters) and the countersunk impressions for the filters eliminate protrusion from the ear as well as preventing accidental filter loss (an issue I had with the older design).

In Use

The purchase process begins with ear impressions at your local audiologist. I also recommend getting a hearing test while you’re there; any information about the dips in your hearing’s frequency response is quite useful (whether it be sobering or encouraging).

L-R: Picture 1, 2, 3
L-R: Picture 4, 5, 6

First, small “sponges on a string” are inserted deep in the ear canal to act as seals that keep the mold material (picture #1) away from your sensitive eardrums. Prepare to be a little embarrassed by wax deposits beyond your swabs’ reach that sometimes cause a little discomfort when compacted. Next, the doctor mixes the molding putty with a catalyst, folds it with his hands until it’s all warm and pliable (picture #2), loads into a large “syringe” and injects it into the ear canal (picture #3) while an assistant pulls back the pinna for better access (picture #4). Fear not, as the sensation is odd; the sound is like descending into the abyss and the pressure is uncomfortable, but it’s actually kind of fun and won’t harm you. After setting up for a few minutes (picture #5 or #6), hardened molds are ready for shipment to Etymotic (picture #7 or #8).

L-R: Picture 7, 8
L-R: Picture 9, 10

The finished plugs (picture #9) are delivered with your choice of attenuators. Choosing the right attenuation is crucial. Since I have some experience in using these over the years, I do feel comfortable making some recommendations here. The ER-9 offers the best overall sound to my ears, with the truest top end and the most fidelity, despite the better “on paper” performance of the ER-15. The ER-9 sounds good enough to not compromise the quality of listening for even sensitive sources like classical music and allows unimpeded conversation without much need to “lean in.”

The only drawback of the ER-9 is that -9 dB is only enough attenuation for moderately loud situations. With the ER-9, I tried mixing monitors on a 105 dB stage as well as participating in a rehearsal within a 20 x 20-foot space; I found the levels hot enough for fatigue and therefore damage. Although I’m not recommending the ER-9 for loud concerts either, they are invaluable for either car or airplane travel, reducing fatigue and irritability considerably.

The ER-25 offers an amazing amount of attenuation, with a significant drop in high-end and fidelity, yet is still superior to typical foam or plastic plugs. I’m only recommending these for punishing environments like monitor world (when you reside too close to FOH stacks), or for onstage guitar techs, loud rock/metal performers, NASCAR enthusiasts and the like; they are not “hi-fi” enough for pleasurable listening. ER-25s are for pros who need them, not for hobbyists who desire them. Speech is greatly impaired, and the bottom end can still punish your ears into pain (remember that very low frequencies are inducted through bone and flesh; you feel lows, and it seems just like you’re hearing them), so use them when needed with caution.

I’d venture to guess that 90 percent of potential ER Series use is best suited to the ER-15. The frequency response is good with a little bump at 100-200 Hz and a little dip at 4-6 kHz, plus the rolled-off top.

Can you mix using the ER-15, you might ask? Sort of — get your mix going, balance it and then insert the plugs. Re-adjust your perception, and you can blend confidently from there. The only catch is that you’ll miss those first few seconds when any feedback slowly starts to swell and will finally catch it right when it starts to kick in. (This fact troubles me, as I pride myself in yanking down bad freqs before anybody else notices.)

Can you perform in them? Sort of — they’re “no brainers” for drummers; the particulars of the response curve seem to tame high-mid harshness in a way that clarifies mids and melodies. Instrumentalists should be good as well, with that pleasant clarifying of drums and reduction of high-mid “noise.” But for vocalists? Sorry, but no way. Singing distorts the shape of one’s face and ear canal, creating sudden loud bursts of leakage when the mouth is widely open forming vowels and sustained notes, thus in-ear monitors (IEMs) are still the best solution for the hearing protection of vocalists on loud stages.

Although just seldomly useful in the studio (when doing loud overdubs with the control room acting as a live room, maybe) the ER-15 is also useful for concert-going, club shows, sporting events, yard work (mowing the grass, for example) and traveling, where attenuation and intelligibility must be in balance. After years of reliance, I’m now rather sensitized to what excessive SPL sounds like, and I find myself carrying the ER-15 ‘plugs most everywhere, discovering new applications on a regular basis.


Please pardon my frank endorsement, but I have purchased ER Series earplugs with ER-15 filters for my wife, effectively persuaded band members to buy them, and am now recommending them to you. My reasoning is simple: Hearing loss is permanent and we need to hear as accurately as possible for as long as we can. These ER Series earplugs simply work and approximately $150 (depending on your local audiologist’s fees) is a small price to pay to insure long-term, pro-level listening by avoiding hearing damage.

Price: Contact your local audiologist for the cost of a custom mold fitting; $40 per pair (replacement filter buttons)
Contact: Etymotic Research |

Rob Tavaglione owns and operates Catalyst Recording in Charlotte, NC.