Etymotic ER4SR Studio Reference Earphone

The ER4SR is a high-performance in-ear monitor with a single driver. It's made of anodized aluminum and is machined with tight tolerances to produce an accurate, slim design. The included cable is of high quality and replaceable to improve durability. Etymotic is known for its top-notch passive noise isolation, which ranges from 35-42dB, making it better than most custom IEMs and foam earplugs. ER4SR is perfect for sound engineers, audiophiles, and consumers who want the most accurate in-ear monitors. There are two ER4 models, the ER4SR and ER4XR, both using the same BA driver but with different bass tuning. The ER4SR is a reference model that has a flat frequency response for precise sound reproduction. On the other hand, the ER4XR has added bass for a fun listening experience. Etymotic aims to have a "perceptibly flat" frequency response by accounting for the resonance in the average ear canal and compensating for it with higher SPL in the 2-5k range. The target curve is based on 20 years of research in human hearing and acoustics. To accurately reproduce a live performance, in-ear monitors must take into account the acoustic properties of the ear. The ear's resonance and horn effects change a flat audio signal into sound with a 2700Hz boost, which is what the eardrum hears in a typical ear. This is why there's a "hump" in the frequency response graph, ensuring the eardrum perceives a flat frequency response for all frequencies.