In 1956 Amar Bose was finishing his doctorate at MIT when he bought himself a new hifi system, and it sounded nothing like live music. He called the gap "a problem that began to obsess me." That question pulled him into psychoacoustics, the study of how people actually perceive sound. In a concert hall, most of what reaches you has bounced off the walls and ceiling first, so his 901 speaker of 1968 aimed most of its small drivers at the wall behind it. Julian Hirsch of HiFi/Stereo Review heard the sound spread evenly across the wall, with no hole in the middle. Bose kept asking what listeners hear rather than what the meters show, and today his QuietComfort Ultra headphones play a tone when they wake and tune themselves to the shape of each listener's ears. Bose suits listeners who want a spacious sound and headphones light enough to wear for hours.

For most listeners today Bose means headphones, and the QuietComfort Ultra is the one to start with. Spend some time with the EQ in the Bose app. Odi of RecordingNow, a music producer and audio engineer, tried settings for days before he cut the bass a little and raised the mids and treble, and then he was "hearing things I never noticed before" in songs he knew well. Phones with Snapdragon Sound can send it aptX Lossless, and Odi recommends a USB-C dongle such as Questyle's for an iPhone. If you prefer earbuds, TechGearLab's testers found that the QuietComfort Ultra Earbuds had the most expansive soundstage of any earbud they had reviewed. If you find a used pair of 901s, make sure the equalizer that comes with them was made for that series. Lucio Cadeddu of TNT-Audio sets them 30 to 45 cm from a bare wall, and Hirsch advised at least 60 watts for loud listening.

Bose started his company in 1964 to put his own loudspeaker patents to work, and by Bose's account its small staff did military power work by day and explored acoustics at night. The first speaker built on the reflected-sound idea, the 2201 of 1966, aimed 22 drivers into the corner of a room. The 901 followed in 1968, and Cadeddu notes that Sherwin Greenblatt, one of Bose's best MIT students, shares credit for it. That September Hirsch wrote that it "ranks with a handful of the finest home speaker systems of all time." It stayed in production for nearly five decades. The headphones began on a Swissair flight in 1978. Bose found the airline's headphones spoiled by airplane noise and worked out the math for noise cancelling before landing. In 1986 prototype headsets protected the hearing of pilots Dick Rutan and Jeana Yeager on Voyager's nonstop flight around the world, and QuietComfort arrived in 2000. Cadeddu, listening to a restored first-series pair in 2024, gave the 901 a place in what he called the Olympus of loudspeakers.