Ray Dolby

Ray Dolby

Ray Dolby, founder of Dolby Laboratories, Inc., was born in Portland, Oregon, in 1933. From 1949 to 1952 he worked on various audio and instrumentation projects at Ampex Corporation, where from 1952–57 he was mainly responsible for the development of the electronic aspects of the Ampex videotape recording system. In 1957 he received a BS degree from Stanford University, and, upon being awarded a Marshall Scholarship and a National Science Foundation graduate fellowship, left Ampex for further study at Cambridge University in England. He received a PhD degree in physics from Cambridge in 1961, and was elected a Fellow of Pembroke College (Honorary Fellow, 1983). During his last year at Cambridge, he was also a consultant to the United Kingdom Atomic Energy Authority.

In 1963, Ray took up a two-year appointment as a United Nations advisor in India, then returned to England in 1965 to establish Dolby Laboratories in London. In 1976 he moved to San Francisco, where his company established further offices, laboratories, and manufacturing facilities. He holds more than 50 US patents, and has written papers on videotape recording, long wavelength X-ray analysis, and noise reduction.

Ray is a Fellow and past President of the Audio Engineering Society, and a recipient of its Silver and Gold Medal Awards. He is also a Fellow of the British Kinematograph Sound and Television Society and an Honorary Member of The Society of Motion Picture and Television Engineers, which in the past has also awarded him its Samuel L. Warner Memorial Award, Alexander M. Poniatoff Gold Medal, and Progress Medal. The Academy of Motion Picture Arts and Sciences voted him a Scientific and Engineering Award in 1979 and an Oscar in 1989, when he was also presented an Emmy by the National Academy of Television Arts and Sciences. In 1986, Ray was made an Honorary Officer of the Most Excellent Order of the British Empire (OBE).

In 1997, Ray received the US National Medal of Technology, the IEEE's Masaru Ibuka Consumer Electronics Award, and the American Electronic Association's Medal of Achievement. That year he also received an honorary Doctor of Science degree from Cambridge University, and in 1999 was awarded an honorary Doctor of the University degree by the University of York.

Dolby Noise Reduction System

In this age of digital audio it should come as little surprise to anyone that cassette tapes do not have the same basic fidelity as compact discs (CD). The dynamic range available, between the noise floor and the highest signal levels that can be recorded without distortion, is a fundamental limitation of magnetic audio tape itself. Even if you make cassette recordings from noise-free sources like CD, when the music stops between songs, tape hiss intrudes. What we call hiss is the noise created by the magnetic particles on the tape, and it can obscure the quality of the music and become annoying. Dolby noise reduction has made it possible to protect the music from tape noise, and helped make cassette the most popular audio product ever devised. Here's how it works.

Noise can be reduced using Dolby B,C and S noise reduction system.

Dolby noise reduction is a two-step process:

Step 1.

When music is being recorded, it is encoded just before reaching the tape. The purpose of encoding is to raise the level of soft, high-frequency passages so they become louder than the tape's noise. During the trip through the Dolby encoder, loud passages (that hide tape hiss) are not altered. Soft, high-frequency passages (that tape hiss affects) are made louder than normal as they are recorded on the tape.

Step 2.

When playing back the tape, the sound is decoded by a precise mirror-image process of the encoding in

Step 1. The loud sounds are left unaltered, while the soft, high-frequency sounds are lowered back down to their original levels. (You may have noticed that Dolby B tapes sound brighter when played without any Noise Reduction decoding. Now you know why! You are hearing the encoded sound, not the original.

NOISE REDUCTION TAKES PLACE DURING DECODING. Tape Hiss is added to the recording during the recording process. In step 1 we learned that the Dolby encoder boosted (made louder) the soft, high frequency passages before the signal reached the tape and before tape hiss was mixed in.

During Step 2, the Dolby decoder doesn't "know," as it scans the signal coming off the tape, that tape noise has been added to the music–it just goes about the business of reducing the encoded sounds to their original levels, with the noise automatically getting the same treatment. The result? Completely restored musical balance but with less hiss in the reproduced sound (see figure 1).

Dolby Noise Reduction System

Such encode-decode systems are generally called "companders." They compress the range between loud and soft when recording and expand the range back again on playback, and reduce noise in the process. While Dolby B-type, C-type, and S-type noise reduction systems all operate as companders,

there are many differences in the amount of noise reduction, the methods used to achieve it, and the level of technology used in each.

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