Page 67 - Spring 2015

When Brüel & Kjær A/S moved to Nærum, the partners made three commitments to each other. (1) All instruments should be produced in Denmark, (2) there would be no de- velopment for the military, and (3) the company should be self-financed and independent of any banks. The second commitment was because WWII had just ended. Because of this commitment, the company was able to sell instruments behind the Iron Curtain without any embargo during the Cold War.
The level recorder, used to measure sound level versus time, was not expected to be sold in greater numbers. Kjær was convinced that the company could not sell more than 50 units, and he and Brüel had an agreement that they should not produce anything that could not be sold in at least 75 units. Brüel felt that the company could sell 150 units, so he had to produce the first recorders in Sweden. Later the production was continued in the factory in Denmark, and the total number of level recorders produced and sold over 30 years, after being updated a number of times, was 25,000. Brüel felt that a reason for this sales success was a three page article published in the Journal of the Acoustical So- ciety of America (Brüel and Ingård, 1949), and, of course, the worldwide need for such an instrument. [To view article visit: http://goo.gl/dv7Tpl ].
Another successful line of equipment developed, manu- factured, and sold by Brüel & Kjær A/S is the condenser microphone. The microphones available previously in the market had the drawback that they became more sensitive with age, gaining about 1–2 dB per year in sensitivity. They were based on a diaphragm clamped between an outer ring and the main housing of the microphone. The diaphragm had to be under stress all the time, but clamping it would permit the diaphragm to move very little due to tempera- ture variation and thus change the sensitivity. This problem was solved by Brüel & Kjær A/S by directly bonding the diaphragm to the housing either through welding, hard sol- dering, or electroplating. This major improvement together with other improvements gave the company a position as the leading manufacturer of quality microphones with an export sale through 25 years between 5 and 9 million dol- lars US per year. The microphones were also used in preci- sion sound level meters made by Gunnar Rasmussen, one of Brüel’s oldest coworkers. This device was given the shape of a gin bottle to minimize reflection of the sound waves back to the microphone.
Noise-produced hearing damage had been an field of inter- est to Brüel. He found that the human ear has two time con- stants, a short one of 30–50 μs and a longer one of about 100–150 ms. This could explain why hearing damages start at higher frequencies, around 4–7 kHz, even if the noise lev- el around 200–2,000 Hz is 20 dB higher. This explains why short duration but very intense hammer strokes will not be heard or measured with their full amplitude but that the nerves will be exposed to the full amplitude and will be dam- aged. The Institute of Acoustics in England awarded Brüel the Lord Rayleigh Gold Medal in 1975 for this discovery.
Brüel was also fighting for better weighting curves because it was found that the A-weighting was incorrect in the impor- tant frequency range of 2.5–8 kHz, where it gave 8 dB low- er results. Per found that Karl Kryter’s D-weighting curve (Kryter, 1970) was much more correct.
A few sentences by Per Brüel characterize his attitude toward the work and from the unofficial rules of conduct: “Running a business is about having fun. Having fun is the best way to use your skills. We want talented people who can think for themselves, who are creative and also a bit lucky. Em- ploy good people; don’t tell them what to do when they start work, because people will find that out for themselves, mak- ing them highly inspired.” And about having fun, his vision statement is: “We shall have fun and we shall make money. On the other hand we shall not have so much fun that we do not make money, and we shall not make so much money that we do not have fun.” These are the words of a charis- matic and inspiring company director.
Brüel & Kjær A/S had an annual growth rate of about 10% in production, sales, and profit for many years, and the com- pany became the “flagship” of the Danish electronic industry in the 1980s. In 1988, the yearly turnover was close to 800 million DKK (US$ 125 million) and the staff included 3,200 employees.
From the very beginning of the company, Per Brüel always considered the market for the company’s products to be global. Moreover, his choice of new products to be devel- oped has always been based on customers’ need. Because the company from the beginning had very few competitors, Per rushed to fill in this competitive vacuum through marathon driving and flying trips to the European countries, to the United States, to Russia (visited the first time in 1950), and to China (visited the first time in 1953).
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