Affordable Ultrasone HFI-450 headphones use the same S-Logic Surround Sound technology found in Ultrasone's legendary HFI-15G headphones. The closed-back HFI-450 offers the same powerful, clear sound reproduction that Ultrasone users have come to expect. Entry-level HFI-450 headphones are specifically for audiophiles on a budget who still want the famous Ultrasone sound for home and studio. Ultrasone's S-Logic Natural Surround Sound creates a 3-D sound field with proven psychoacoustic principles. No additional equipment is required. Sound reflecting off of the outer ear helps us to localize its source. The Ultrasone S-Logic system directs sound to the outer ear before it enters the auditory canal, creating natural 3-dimensional sound. Instead of trying to squeeze a band inside your head, Ultrasone HFI-450 headphones immerse you in a rich, natural musical environment. Safer hearing Ultrasone S-Logic not only creates natural surround sound, it also reduces sound pressure levels as much as 40 percent (3-4 dB), while maintaining the same perceived loudness. Listening at lower volumes without losing the perception of volume increases listening pleasure while reducing the risk of ear damage. You'll have hours of fatigue-free listening. Even at very low volume levels, Ultrasone HFI-450 headphones still deliver the same spacious sonic effect, so you to hear every sound as though you were there when it was recorded. For even greater safety in long listening sessions, Ultrasone employs a special MU Metal shielding (ULE), for Ultra Low Emissions that reduces electromagnetic radiation by 98 percent as compared to conventional headphones.