ER4XR is the highest-performing single driver in-ear monitor. The IEM shells are made of anodized aluminum, CNC machined with extremely tight tolerances. Using a single Balanced Armature (BA) driver allows for extremely accurate IEM without the added complexity of crossovers, and helps keep the aluminum body small and slim. The included high-quality user-replaceable cable is reinforced and twisted, to improve longevity and durability.
 
Etymotic IEMs are world renowned for their class-leading passive isolation, providing 35-42 dB attenuation (depending on ear tips used and the depth of insertion). For comparison, most custom IEMs provide approx. 25-28dB attenuation and foam ear plugs attenuate up to 32 dB. The ER4XR is a must-have for audiophiles and consumers, looking for very accurate in-ear monitors with a taste of added bass, for a more “fun” sound signature.
 
Frequency response graphs and Etymotic’s target:
Etymotic’s target frequency response graph represents a “perceptibly flat” frequency response. Our goal is to have a flat frequency response curve when the music notes hit your eardrums. To achieve that, we need to account for the resonance inside the average ear canal, since IEMs bypass the outer ear structure. The result is the need for higher SPL in the 2-5k region (lower treble) for compensating said resonance. That is the reason for the “hump” in that region.
The target curve that Etymotic is using for tuning our IEMs differs slightly from the Harmon preference curve. It was developed in-house more than 20 years ago, leveraging on our human hearing expertise and acoustics research.
 
Accurate Earphone Reproduction
When tuning in-ear monitors to accurately reproduce a recording of a live performance, our goal is for the sound hitting the eardrums to be identical to that at the original performance. To achieve this, the acoustic properties of the ear must be factored in. The acoustic resonance and horn effects of the ear change a flat audio signal entering the open ear into sound with a (2700 Hz) high-frequency boost, which is the same response heard at the eardrum in a typical ear. That is the reason for the “hump” in the frequency response graph below, which assures the eardrums perceive a perfectly flat frequency response for all frequencies.
Channel-Matching Compliance Graph supplied with each ER4SR and ER4XR.
 
Included
- In Ear Monitors
- Detachable, 5 ft. cable with 3.5mm gold plated stereo plug
- Assortment of eartips: 4 Dual Flange Silicone Pairs: S, M, L, XL. 2 Triple Flange Pairs: Standard and Large. and 2 Foam Pairs: Standard
- Filter removal tool and replacement filters to protect the BA drivers from ear wax
- Shirt clip
- Zippered storage case
- Channel-Matching Compliance certificate