Most headphones give you an unnatural listening experience by bypassing the pinna the external portion of the ear largely responsible for sound localization
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Most headphones give you an unnatural listening experience by bypassing the pinna — the external portion of the ear largely responsible for sound localization — and piping program material directly into the ear canal. In a natural listening situation, sound is diffracted when it strikes the pinna. The brain analyzes the resulting phase discrepancies, time delays, and tonal colorations (caused by comb filtering), and it forms conclusions as to the localization of discrete sounds.

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The Proline 750''s left and right ear capsules fold up toward the headband for compact storage.

The Ultrasone Proline 750 circumaural, dynamic headphones ($399) were designed to produce a more natural listening experience by offsetting its left- and right-channel, 40 mm titanium drivers from the listener's ear canals so that program material is diffracted by the pinnae before entering the ear canals. The company calls its proprietary approach, which employs no signal processing, S-Logic Natural Surround Sound.

S-Logic purportedly helps protect the listener's hearing by producing the same perceived volume as traditional headphone designs, but with sound-pressure levels reduced by up to 4 dB. Another health-related design aspect is the incorporation of Mu-metal shields, which Ultrasone claims reduce the head's exposure to potentially harmful low-frequency magnetic radiation by up to 98 percent.

Head Games

The Proline 750 comes with useful features and ships with several accessories. The left and right ear capsules fold up toward the headband so that they fit neatly inside a supplied nylon storage bag. You close the bag by pulling on a drawstring. No toggle or other locking mechanism is offered. Ultrasone gives you two detachable cables — one straight and about 9.4 feet long, and the other partly coiled and roughly six feet long when not stretched. You choose the cable you prefer, and then push and screw its stereo 3.5 mm plug into the base of the 750's left ear capsule. The other end of each cable is fitted with a ¼-inch stereo phone plug. A ¼-inch female-to-3.5 mm male stereo adaptor is also included. All connectors are gold plated. The 750 also ships with a spare pair of ear pads, a demo CD, and an instruction manual.

The Proline 750 weighs a little more than 10 ounces without a cable attached — about the same as the average pro headphone set. The unit's impedance is 40Ω, and its frequency response range is listed at 8 to 35,000 Hz (with no tolerances given).

Testing 1, 2, 3

I first used the 750 while recording my own lead vocals. The headphones felt somewhat rigid on my head, no matter how I adjusted the headband. The 750's partly coiled cable was too short for use without an extension cord, but the straight cable gave me plenty of length for my setup.

The 750 provided excellent isolation and respectable sensitivity — about the same as that of my AKG K271 Studio headphones. But my vocal sounded atypically lean in the upper-bass and low-midrange bands and overly bright in the upper-mid to high frequency range. The vocal also sounded more ambient and less focused than it did on the K271s.

Next, I listened to several familiar pop, rock, and country recordings, including my own recently completed mixes. The 750's transient response and reproduction of high-frequency details were both excellent. I was amazed at how much the bass range lows were extended by — the 750 gives subwoofers a run for their money, accurately reproducing the lowest Chapman Stick notes on Paula Cole's “Tiger.” But the 750 sounded lean in the upper-bass and low-midrange bands and hyped in the low highs on all the material that I listened to. I could hear loads of detail in the upper-midrange band, but only because the low mids were unsuitably lean and had negligible frequency masking. The overall sound was thin, harsh, and cutting, especially on vocal-heavy material and mixes that had a moderate bottom end. Vocals, electric guitars, and violins routinely sounded harsh, and snare drums sounded papery thin.

While the 750 produced a subtly increased sense of ambience, I wouldn't characterize the effect as a surround or a natural experience, as the name S-Logic Natural Surround Sound implies. The sound was more diffuse, but localization wasn't especially enhanced. For panning elements in a mix, the headphones did not give a reference that was better than that provided by conventional headphones. (I've heard spatialization software in headphones that has conveyed the illusion of a natural acoustic environment that sounds better than the Proline 750s do.) You'll have to hear the S-Logic effect for yourself to decide whether it's an improvement over what traditional headphone designs offer. To me, the 750's subpar spectral balance made the effect moot.

Overall Rating (1 through 5): 2