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Murray Campbell

(b Cleveland, OH, July 19, 1915; d Pittsburgh, PA, Feb 10, 2010). American scientist and acoustician. After studying physics at Case Institute of Technology (BS 1937), he carried out research in nuclear physics at the University of Illinois (PhD 1941). He then joined the Westinghouse Electric Corporation, remaining with the firm for the rest of his professional life; he retired in 1980 after a distinguished career culminating in six years as Director of Research and Development. In his youth he had become an accomplished flute player, and during his undergraduate studies at Case he encountered the notable acoustician Dayton C. Miller. This meeting led to a lifelong interest in the acoustics of the flute, and Coltman developed a laboratory at his home in which he conducted many important and illuminating experiments on flutes and flute playing. Particularly significant was his contribution to the understanding of the subtle interaction between the air jet blown across the flute embouchure hole by the player and the resonances of the air column within the flute pipe. Over four decades, starting in the mid-1960s, he published more than 40 papers on the acoustics of flutes and organ pipes. He was a member of the National Academy of Engineering and a Fellow of the American Physical Society and the Institute of Electrical and Electronic Engineers....

Article

Echo  

Murray Campbell and Mary Térey-Smith

The repetition of sound after a short time interval. In addition to the applications discussed below the term is used for a signal-processing device (also known as a delay) that produces a slightly delayed playback of sounds either by a tape loop or by digital delay; see Electric guitar §2 .

See also Organ stop .

Natural echoes arise from the reflection of a sound wave by a solid surface, such as a wall or cliff. For the echo to be perceived as distinct from the original sound, the extra path length travelled by the reflected sound wave must have a minimum value of around 17 metres, corresponding to a minimum time interval of 50 milliseconds between direct and reflected sounds.

The reverberant sound field in a concert hall is created by multiple reflections of sound waves. In a well-designed hall, the direct sound reaching a member of the audience is followed by a series of reflections within a time interval of around 35 milliseconds. These ‘early delayed arrivals’ are not heard as separate echoes; because of the ‘precedence effect’ they are perceived as a reinforcement of the direct sound. Subsequent reflections blend smoothly into the reverberation. A concave surface, focussing sound waves into a particular part of the hall, can give rise to an audible echo; a ‘flutter echo’ can arise from successive reflections between parallel walls....

Article

Laurence Libin

Pure-tuned harmonium developed by the German physicist and music theorist Arthur Joachim von Oettingen (b Dorpat, Livonia, 28 March 1836; d Bensheim, Germany, 5 Sept 1920) and built by Schiedmayer in Stuttgart. An example from 1914 is in the Musikinstrumenten Museum, Staatliches Institut für Musikforschung, Berlin. Designed to sound pure 3rds, 4ths, and 5ths, it is based on an octave division into 53 (in some versions, 72) tones and has a complex multilayered but symmetrical keyboard similar to that of Bosanquet’s enharmonic harmonium. Oettingen studied astronomy and physics at the University of Dorpat and continued his education in Paris and Berlin. He was appointed a professor in Dorpat in 1863 and moved in 1893 to Leipzig, where he worked until 1919. He advocated the theory of ‘harmonic dualism’, later elaborated by Hugo Riemann, and introduced the interval measurement called the ‘millioctave’, based on division of the octave into 1000 tones. See ...

Article

Edwin M. Ripin

(Fr. table d'harmonie; Ger. Resonanzboden; It. piano armonico, tavola armonica)

The thin sheet of wood in a piano, harpsichord, clavichord, zither, or the like, that serves to make the sound of the strings more readily audible and helps to form the characteristic tone quality of the instrument. A string presents so small a surface to the surrounding air that its vibrations cannot set the air into vibration with any great efficiency; as a result, the sound produced by a string in the absence of a soundboard, although it may well sustain for an appreciable time, is hardly loud enough to be used for any musical purpose. The soundboard, coupled to the strings by means of one or more bridges over which they pass, provides a larger vibrating surface so that the air can be set into vibration more efficiently and a louder sound can be heard. The soundboard does not serve as an amplifier in the same sense as an electronic circuit or device, since it adds no energy from an outside source; rather, it enables the energy already imparted to the string by a hammer, plectrum, tangent, or the like, to be dissipated more rapidly, so this energy is converted to a sound of higher intensity that lasts for a shorter time. The particular resonance and vibrational characteristics of the soundboard determine which components of the complex vibration of the string will be given particular prominence, and the rate at which they will be dissipated; consequently the shape, thickness and ribbing of the soundboard are of primary importance in determining the quality of the instrument of which it is a part....

Article

Philip Bate

In the terminology of organ building, a flue pipe in which the end remote from the mouth is closed by a movable stopper or airtight cap. This provides a means of tuning.

In general, a stopped pipe is any tube that communicates freely with the ambient air at one end and is completely closed at the other. The Air column in such a tube will vibrate with an antinode at the open end and a node at the closure. The fundamental is approximately an octave lower than that given by a pipe of equal dimensions open at both ends, and its wavelength is four times that of the tube itself. The harmonic series of a stopped pipe lacks the even-numbered partials; Overblowing begins a 12th above the fundamental. Because it shows this characteristic the clarinet is sometimes loosely termed a stopped pipe. Among folk instruments the stopped pipe is represented by many end-blown flutes of varying degrees of sophistication....