Etymotic Research ER4-S (Stereo) microPro In-Ear Earphone

In a Class by Itself

Etymotic invented noise-isolating, in-ear earphones. Etymotic's original insert earphone design, developed for auditory research and medical diagnostics, used balanced armature receivers and established these speakers as the gold standard for high-definition, in-ear earphones. The ER•4 MicroPro series earphones were the first earphones commercialized using this technology and are recognized as the world leader in response accuracy, to which all other earphones are compared. After more than 20 years, these reference-quality earphones are still the choice of serious sound engineers, audiophiles and musicians.

Backed by decades of research and development for the ear

• World leader in sound reproduction
  • Unsurpassed frequency response accuracy and sound quality — 86%+ response accuracy from 20 Hz – 16 kHz
  • The only earphones with Accu•Driver™ balanced-armature, precision-matched, custom-tuned drivers
  • Highest output sensitivity in its class
• Timeless style and fit
  • Professional quality and reliability
  • An assortment of noise-isolating ACCU•Fit™ eartip options to ensure proper seal and comfort
  • CUSTOM•FIT option available
• Highest noise isolation
  • First earphones to completely seal the ear
  • 98% (35 dB - 42 dB) noise isolation —highest of any earphones or headsets on the market today
  • Reduction of outside noise reduces the risk of listening at unsafe levels
• Best durability and warranty
  • 2-year replacement warranty
  • Braid-reinforced cable for extremely low microphonic effect
  • ACCU•Filter™ user-replaceable filters protect the balanced-armature drivers from ear wax

Which ER•4 is Right for You?

ER•4PT earphones, intended for sound engineers and audiophiles in constant motion, comes equipped with extra accessories. ER•4PT earphones can be used with portable devices without an additional amplifier—or converted to the ER•4S response with the included P-to-S cable. Compared to the ER•4S, the ER•4PT has 10 dB greater output at high frequencies and 13 dB greater output at low frequencies. The higher sensitivity and enhanced bass of the ER•4PT have made it the most popular earphone in the series. Included with every pair of ER•4PT earphones is an industry-exclusive channel-matching compliance graph, signed by the Etymotic engineer who precision matched and custom tuned the balanced-armature drivers.

ER•4S earphones were designed to compensate for the high frequency emphasis in all CD recordings, in order to provide accurate sound reproduction. Performing musicians often use them as in-ear monitors because the response of the ER•4S matches the response of most typical monitor loudspeakers. The high accuracy and exceptional sound isolation of the ER•4S have made these earphones popular with musicians, recording engineers and audiophiles. ER•4S earphones can be used with a headphone amplifier when using low power portable devices.

ER•4B earphones are for the binaural recording enthusiast. The ER•4B is an ideal earphone for use with material that has not been equalized for loudspeaker playback. It was developed from the ER-1 earphone that is referenced to a flat diffuse field and used primarily for speech reception research, where the goal is to produce the same frequency response at the eardrum as would be produced in the live situation.

Accurate Earphone Reproduction

For earphones to have 100% accuracy, a recording of a live performance must produce exactly the same sound at the eardrum as 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.