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."
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.
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.
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.
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.
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.
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
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.
and assorted testing equipment are frequently moved to accommodate different speaker
arrangements. Even the most subtle changes in a roomsimply sitting on a
couch, for instancecan 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.
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.
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 employeesor
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.