In 1958, John C. Koss teamed up with engineer Martin Lange, Jr. to develop a portable stereo phonograph player with side-wing speakers. The pair demonstrated their new stereo record player at a Wisconsin audio show. One of the product's unique features was a privacy switch, which allowed listeners to hear music by plugging in the World's first SP/3 Stereophone.
The stereophones were intended to be an accessory to deomonstrate the high-fidelity stereo sound that the portable phonograph player delivered, but the revolutionary sound of the Koss SP/3 stereophone became the hit of the show. The original SP/3 stereophone allowed listeners to experience sound as they had never before, forever changing the way we all listen to music. Listeners of the era were experiencing stereo headphones for their first time.
People were won over by this revolution in personal listening. It was around this same time that Koss coined the phrase "Hearing is Believing". John C. Koss remembers the SP/3X, and the challenge of introducing the world to stereophones: "Back then if someone handed you a headset, it had been designed for a telephone operator or a bombardier. The SP/3X meant nothing to anyone until they could actually hear it, and when they did, it was about as exciting as their first ride in a car, or flight on an airplane. The sound of the SP/3X Stereophone was about that exciting." "Because the experience of stereo sound was so new, people would invite the whole neighborhood to come hear it. They wanted to run their own hi-fi show. That's kind of the way it worked all along. You had to hear it to believe it."