A Look at Bose® R&D

You have high expectations for Bose® sound. Because your need for consistent, high-quality performance begins and ends with the speakers, we extensively test ours before they travel to your home. But the journey is quite different from that of the average speaker. Consider our specialized approaches to testing, and you'll understand why we say, "To be better, you have to be different."

The anechoic chamber

One of the more fascinating rooms at Bose is the anechoic chamber (literally, a room with no echoes). Anechoic chambers are designed to measure a speaker's frequency response without the reflected sound that's characteristic of normal rooms. The quiet solitude in an anechoic chamber results in absolute measurements. In fact, the oldest wedge-based anechoic chamber, built in 1940, was once cited in the Guinness Book of Records as the world's quietest room.

Our anechoic chamber sits on springs, a room within a room, isolated from the rest of the Bose Research and Development facility. Inside, dense and meticulously arranged fiberglass wedges protrude from all angles. The 24" wedges absorb all sound above 100Hz, eliminating all echoes. This ensures we only record sound coming directly from the speaker.

It might be thought of as the ideal environment in which to test. But you don't listen to speakers in anechoic chambers. So while some manufacturers use such a room to set a speaker's tonal balance, the measurements bear little relation to what you might actually hear in your room. We are different.

Bose engineers use the anechoic chamber for a few specific measurements, such as the directional characteristics of a speaker. A speaker is placed on a turntable, which rotates while one or more microphones are used to take measurements. This tells us how the sound is radiated in all directions from the speaker and gives us insight as to how we can change its interaction with a common room. This is a crucial step, since the performance of a speaker in any given room is inseparable from the room itself.

It's all about listening

There are 10 listening rooms in the Bose R&D facility. Each has the characteristics of a typical home listening area, from a small apartment to the largest family room. Complete with furniture, bookcases, windows and more, these rooms are used to design, measure and listen to our loudspeakers. Then, members of our certified listening panel rate speaker performance in these rooms and in their own homes.

These listening tests are treated as scientific measurements, not just personal opinion. We even developed a specific vocabulary to quantify test responses because one person's description of "muddy sound" may not mean the same as another's lacking high frequencies. This innovative approach ensures all Bose speakers are judged along a common scale.

As for the listening judges themselves, becoming a certified member is comprehensive and rewarding: Each member must develop and hone an innate knowledge of what live music sounds like by frequently attending concerts. Nice work if you can get it, especially considering the renowned music scene in nearby Boston.

The Reference Room

Some people love to listen to their speakers. And then there are the engineers at the Bose Research and Development Center. Bose sound engineers spend most of their time listening to, testing and measuring speaker performance in one of R&D's ten listening rooms.

Each listening room is set up to replicate a typical home listening area. But designing our speakers in real listening rooms poses problems. Especially if we're trying to replicate a measurement after a period of time has elapsed.

Couches, chairs and assorted testing equipment are frequently moved to accommodate different speaker arrangements. Even the most subtle changes in a room—simply sitting on a couch, for instance—can compromise attempts at making consistent measurements. So, at a later date, how do we accurately reproduce the environment in which original measurements were made?

Bose sound engineers designed a unique, unchanging reference room. Walk in and you'll see regular furniture. But picture this: It's mounted on end. Think of it as a room tipped on its axis. You're actually standing on a "wall" and looking at a "floor" filled with furniture, where you would normally be looking at a wall.

This mind-bending layout makes it impossible for anyone to sit on the furniture or alter so much as a thread of material. It remains absolutely constant from year to year and does not change acoustically over time. So the Bose engineers take "reference" measurements in this room as well as measurements in more normal rooms. It may look strange at first, but the end result is a speaker that can have its performance verified at any time in the future, and is properly designed (and tested) for the places you listen most.

Reliability Testing in the Bunker

Designing a speaker to sound realistic is only part of the story. It also has to work well for many years, even if constantly played at extremely loud levels. So we do extensive analysis to ensure our speakers will survive the heat and mechanical stresses generated by long, loud use. This means lengthy testing periods at high power levels. Such tests produce a tremendous amount of noise, so we built a special testing area we called the Bunker.

The Bunker is separate from our R&D facility so the noise it generates won't disturb employees—or our neighbors. How loud is it? The total power of the amplifiers used for testing is about 120 kilowatts. This is the equivalent of hundreds of ordinary audio systems. Without such a structure, even neighbors a mile or so away might have reasonable cause to complain.

We perform reliability testing for specified periods, such as 300 hours of highly accelerated testing, and sometimes until the speaker simply has nothing left to give. Testing to such a point of failure can take a long time; some of our speakers have run non-stop for years before expiring. It's this level of extensive testing that enables long-lasting Bose® quality sound for your listening pleasure.