One of the important conditions which must be met by any speech transmission system is that it should transmit properly a sufficient range of speech intensities. In long‐wave radio telephony, even after the speech waves are raised to the maximum intensity before transmission, there remain energy variations such that weak syllables and important parts of strong syllables may be submerged under heavy static. The compandor is an automatic device which compresses the range of useful signal energy variations at the transmitting end and expands the range to normal at the receiving end, thus improving the speech‐to‐noise ratio. This paper deals with some of the fundamental characteristics of speech waves and explains how the task of changing them for transmission over the circuit and restoring them at the receiving end is accomplished. It is also shown that raising the strength of the weaker parts of speech gives these results: 1, the successful transmission of messages for a large percentage of the time previously uncommercial; 2, a reduction of the noise impairment of transmission for moderate and heavy static during time classed commercial; and 3, the ability to deliver higher received volumes due to the improved operation of the voice controlled switching circuits. In addition to these advantages, the compandor makes it possible to economize on radio transmitter power in times of light static.

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The art of controlling the amplitude range of telephone signals involves recognition of certain characteristics in addition to those used to specify the performance of ordinary transducers. Fundamentally, three kinds of characteristics are necessary to distinguish different range control devices. They are (1) the steady‐state input‐output characteristics, (2) the time actions, and (3) the range over which they function. In some cases, several secondary characteristics may be of interest, but they need not be considered in determining to which class a particular device belongs.

Australian scientist Shirley Jeffrey was a pioneer in oceanographic research, identifying the thentheoretical chlorophyll c, and was a worldwide leader in the application of pigment methods in quantifying phytoplankton as the foundation of the oceanic food supply. Her research paved the way for the successful application of microalgae in aquaculture around the world. Jeffrey earned bachelor's and master's degrees at University of Sydney, majoring in microbiology and biochemistry, followed by a PhD from the King's College London Hospital Medical School. Returning to Sydney, she was hired by the Commonwealth Scientific and Industrial Research Organisation (CSIRO) to research chlorophyll c. Following this successful effort, she became a research fellow at the University of California, Berkeley from 1962 to 1964. She then became affiliated with the Scientific Committee on Oceanic Research. After a 1973 sabbatical at the Scripps Institution of Oceanography in San Diego, she returned to CSIRO, where she spent the rest of her career.

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