In-ear monitors have been in heavy use in touring and broadcast systems for years, and Ultimate Ears, a leading manufacturer of such products, recently developed a version for the studio. Called the In-Ear Reference Monitors ($999), they''re designed for mixing, offering both flat frequency response and excellent isolation. The company collaborated on the design with the engineering staff at Capitol Studios in Hollywood.

HEAD SPACE
Mixing on headphones, no matter how flat their frequency response, is not the same as listening on speakers. Among other factors, you''re hearing the sound inside your head, without any of the reflections that occur when listening in a room. Studio headphones are more typically used in the control room to check individual elements, or as an alternate way to hear a mix, rather than as the primary monitor. If you do mix on headphones, it''s important to check the results on speakers, because certain elements are going to sound different.

The flip side of that equation is that unless you''re listening in a room that''s been well-treated, acoustically, you''re not going to get a truly flat response from your speakers, due to the acoustics of the room—hence, the need to audition your mixes in the car, on a boombox, and so forth, to see how they translate.

Ultimate Ear''s intent in designing the In-Ear Reference Monitors, which combine impressive isolation with a flat frequency response, was to help ameliorate the problem of listening in untreated rooms. The idea is to give engineers, producers, and musicians an extremely portable and trusted mixing solution to use in hotel rooms, tour buses, and anywhere with marginal acoustics.

GETTING FIT
Because they''re custom-fit, you don''t immediately receive your product when you purchase the monitors from Ultimate Ears. First, you need to schedule an appointment with an audiologist for a fitting, which costs extra. Ultimate Ears has a network of affiliated audiologists, and they can recommend somebody in your area. The fitting is brief, and consists of foam being injected into your ear canal (it''s totally painless, the only drag is that you have to keep your teeth from moving during the few minutes while the foam hardens into a mold. This requires biting down on a bite block, which causes you to drool—so ask for a bib).

Once the fitting is complete, the molds are sent to Ultimate Ears and your monitors are assembled with a woofer, mid-driver, and tweeter inside. They come in small hard-shell case with your name on it, and with an included cleaning tool and an 1/8-inch to 1/2-inch adapter. Although I''ve been using custom-fit earplugs for years, getting used to putting in the monitors took a little doing. The plugs come in an acrylic housing, which is quite hard, and can be uncomfortable when inserting into your ears. Once they''re seated correctly, however, they feel fine.

REAL WORLD
In addition to offering excellent isolation (- 26 dB), their sound is excellent. Their frequency range is 5Hz to 20kHz—so you can imagine that the bass response is very impressive. I was able to judge bass with them much more easily than with conventional headphones. Since they''re designed for flat response, the high end is clear, but not hyped. The detail and clarity across the frequency spectrum is very good overall. According to an Ultimate Ears spokesman, the optimal listening level is 90-95dB, which gives you the full bass response (and which is also too loud for extended safe listening).

I tried the headphones out over a period of a few weeks, and was able to successfully mix on them. When in my studio, I preferred to listen on speakers while switching occasionally to the Ultimate Ears for additional perspective. However, I can see how they''d be extremely useful in a travel situation. There''s no doubt that these are great-sounding monitors. Whether or not they''ll be worth the money to you depends on whether you do a lot of production (and especially mixing) on the road or away from your studio. If so, I would recommend them highly. If you just want them for your home setup, you''re probably better off putting that money into improving your acoustic treatment or studio monitors.

Overall Rating (1 through 5): 4
Ultimate Ears In-Ear Reference Monitors Product Page