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[acoustical].

A term, meaning ‘not electric’, used in this special sense to designate a recording cut with a stylus activated directly (through a diaphragm) by sound waves rather than by electronic impulses, or, as in ‘acoustic guitar’, an instrument not amplified electronically. It was first applied to recordings in the early 1930s (electric recordings were first made in ...

A term that can embrace all aspects of the science of sound and hearing, but is here treated in two specific senses, that of room acoustics, considered only with reference to the performance of music, and that of sound-source acoustics, limited to various classes of musical instruments and the voice. For other acoustical matters see Hearing and psychoacoustics and Sound; for the history of the subject see Physics of music.

Ronald Lewcock and Rijn Pirn, assisted by Jürgen Meyer

A room that has good acoustics is one in which it is possible to hear each sound clearly in all parts of the room; or, in other words, a room in which the sound is adequately loud and evenly distributed. In addition, it is normally required that the quality of sound being listened to in the room should match the type of sound being produced by the source. Room acoustics are relied on in some cases to sustain the sound in the room after the original source has stopped producing it, thus masking unevennesses in the ensemble, while in other cases sound too much sustained would mask the clarity of individual instruments or small groups. Acoustical problems are further complicated if opera is to be performed, for here every syllable is expected to be clearly heard and understood, and therefore only moderate sustained sound is desirable, yet the large ensemble demands sustained sound. Although scientific study permits a certain degree of accuracy in acoustical design, great difficulty is still experienced in determining the correct specification of the acoustics that ought to be provided....

(Graham)

(b Portland, OR, April 29, 1911; d Los Angeles, Oct 28, 1988). American acoustician. After studying at Reed College, Portland (BA 1932), he undertook postgraduate study at the University of California in Berkeley (MA 1936, PhD 1940). His early research work was in nuclear physics, working under the supervision of Ernest Lawrence in the Radiation Laboratory at Berkeley. In 1945 he was appointed professor of physics at the University of Southern California, and he continued in that post until his retirement in 1980. An accomplished performer on the piano and the bassoon, Backus was awarded the degree of MMus in conducting by the University of Southern California in 1959. In the later stages of his research career he made major contributions to the study of the acoustics of woodwind instruments, brass instruments and organ pipes. In 1969 the first edition of The Acoustical Foundations of Music...

(Fr. battements; Ger. Schwebungen; It. battimenti; Sp. batimientos)

An acoustical phenomenon, useful in tuning instruments, resulting from the interference of two sound waves of slightly different frequencies. The number of beats per second equals the difference in frequency between the two notes: a pitch of 440 Hz will make four beats per second with one of 444 (or 436); three with one of 443 (or 437); two with 442 (or 438); one with 441 (or 439); and the beats will disappear if the two notes are in perfect unison. ...

(Henry)

(b Chicago, Jan 2, 1925; d Cleveland, Aug 4, 1987). American acoustician. His parents being missionaries, he spent much of his childhood in Lahore. After returning to the USA to study at Washington University, St Louis (AB 1948, PhD 1952), Benade was appointed in 1952 to the physics faculty at Case Institute of Technology, Cleveland, which later became Case Western Reserve University. Promoted to a full professorship in 1969, he continued in that post until shortly before his death. A skilled woodwind player, he had an exceptional ability to relate the results of acoustical research to the practical requirements of musicians and musical instrument makers. Benade established a research programme which made many fundamental contributions to the understanding of the operation of wind instruments. Also active in string instrument research, he was a founding member of the Catgut Acoustical Society and its president between 1969 and 1972...

(Pierre Maxime)

(b Paris, Nov 16, 1866; d Toulouse, Nov 15, 1953). French physicist and acoustician. He studied physics at the Sorbonne (1883) and at the Ecole Normale Supérieure (1885–8). After teaching at the Collège de France and the Lycée at Agen, in 1892 Bouasse joined the staff of the University of Toulouse and obtained his doctorate in mathematics. In 1897 he gained the degree of doctorate in physical sciences and was appointed to the physics chair at Toulouse, where he remained for the rest of his academic career. Retiring in 1937, he continued to work in his laboratory until two years before his death. His research interests ranged widely and he made many discoveries of great importance to musical acoustics. In particular, his studies of woodwind and brass instruments provided the essential foundation for the modern understanding of how sound is generated in these instruments. Bouasse's work has been unjustly neglected outside France, partly because he published little in conventional journals. Instead, he wove his own theories and experiments into a 45-volume library of textbooks on classical physics, the ...

(Michael)

(b London, August 26, 1933). English physicist and acoustician. He obtained a BSc in physics from Imperial College, London, later gaining the doctorate there with research into high-amplitude stress waves. After holding a research fellowship at the electronic music laboratory of the Canadian National Research Council in Ottawa, he worked for five years in the acoustics section of the UK National Physical Laboratory, where he carried out research on the psycho-acoustic perception of short duration and very low frequency sounds. In 1966 he was appointed to a lectureship in acoustics at the University of Surrey, where, in collaboration with colleagues in the US, Europe, Israel and Australia, he established a group which became noted for its research into the acoustics of wind instruments and their subjective assessment. He played a major part in the establishment there of the Tonmeister course in music and applied physics. An accomplished trombonist, his most notable research has been in the acoustics of brass instruments, where he supplemented and elucidated physical measurements by applying psychological testing procedures to the assessment of brass instrument tone quality. He developed a non-invasive technique which allows the bore of an instrument to be reconstructed by injecting acoustic pulses into one end and recording the reflections....

A small logarithmic unit used in the accurate description of musical intervals, based on frequency ratios. The interval, in cents, between two tones of frequency f₁ and f₂ is 3986 log₁₀ (f₂/f₁). 100 cents is equal to one equally tempered semitone. See Interval...

(Florenz Friedrich)

(b Wittenberg, Nov 30, 1756; d Breslau [now Wrocław], April 3, 1827). German acoustician. He studied law at Leipzig University before turning to scientific studies. He invented two instruments, the ‘euphon’ and the ‘klavizylinder’, both of which were variants of the glass harmonica. However, he owes his fame to his celebrated experiments on the nodal patterns and corresponding frequencies of vibration plates. He showed that the vibration patterns, often called Chladni figures, could be made visible by sprinkling sand on the plate. The sand is thrown up on vibrating areas and collects around nodal lines. Chladni travelled through Europe playing on his instruments and demonstrating his experiments before many persons and institutions; he encountered Goethe, Lichtenberg, Olbers, Laplace, Napoleon and other notable men of the period. Chladni's experiments stimulated much early work on the vibration of plates and bars and indeed so impressed the Académie des Sciences, Paris, that it offered a prize for a successful explanation of his sand figures and the motion of elastic surfaces in general. His work helped to form the foundation of modern theories, capable of predicting precise vibration patterns for violin and guitar top plates and the soundboards of keyboard instruments....

(b Cleveland, July 19, 1915). American physicist and acoustician. After studying physics at the Case School of Applied Science (BS 1937) he obtained the PhD from the University of Illinois. From 1941 to 1980 he held various research and management positions at the Westinghouse Corp. His research into the acoustics of the flute, carried out in a small laboratory at his home, has contributed significantly to what is known today about the behaviour of flutes and organ pipes. Several of his papers are recognised as standard reference material. His theory of feedback and how this relates to the means by which the flautist produces the desired frequencies and loudness is particularly relevant to performance. He also studied the significance of mouth resonance and the effect of mode stretching on harmonic generation. His work on the intonation of both antique and modern flutes and his critical assessment of Theobald Boehm's methods have helped in shaping current views on the historical development of the instrument....

(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....

A sound that may be heard when two loud musical tones are sounded together but is not present when either of the tones is sounded separately. If the frequencies of two pure tones are f ₁ and f ₂, the frequencies of the combination tones are f ₁+f ₂, f ₁–f ₂, 2f ₁+f ₂, 2f ₁–f ₂, f ₁+2f ₂, f ₁–2f ₂, 2f ₁+2f ₂, 2f ₁–2f ₂ etc. They are usually attributed to non-linearities in the system through which the sound is being transmitted or reproduced. If the only system involved is the ear, they are sometimes described as ‘subjective tones’; the most prominent are the ‘simple’ difference tone, with frequency f₂–f₁, and the ‘cubic’ difference tone, with frequency 2f₁–f₂, where f_1...

A small pitch interval of fundamental importance to temperament and tuning. There are two types of comma. The ‘syntonic comma’ (also called ‘comma of Didymus’ or ‘Ptolemaic comma’) is the difference between a just major 3rd and four just perfect 5ths less two octaves, which is 21.51 cents. The ‘Pythagorean comma’ (or ‘ditonic comma’) is 23.46 cents, being the difference between twelve 5ths and seven octaves. For practical tuning purposes, the difference between the two types of comma is often ignored and the comma is taken to equal 24 cents....

(Winfried)

(b Munich, Aug 16, 1905; d Miesbach, Oct 16, 1990). German acoustician. He studied mechanical and electrical engineering at the Technical University of Berlin, gaining his doctorate in 1932 for a thesis on sound absorption by porous surfaces. Cremer subsequently engaged in acoustical research at the Technical University and the Heinrich Hertz Institute in Berlin. In 1945 he obtained a teaching post at the University of Munich, and in 1946 established an acoustical consultancy firm in Munich. He was appointed director of the Institut für Technische Akustik at the Technical University in 1954 and of the acoustics division of the Heinrich Hertz Institute in 1955. Retiring in 1973, he remained active in teaching and research until his death. Cremer made many important contributions to the solution of practical problems in noise control and building acoustics. He was acoustics consultant for a number of major halls including the Berlin Philharmonie, the Sydney Opera House and the Madrid Concert Hall. A skilled amateur pianist and violinist, in the 1930s he was an enthusiastic exponent of the trautonium, an early electronic instrument. Cremer later became interested in violin acoustics and was one of the leading figures in the Catgut Acoustical Society. His book ...

Music associated with the Creole people, of mixed European and African descent, in the gulf region of the United States, particularly Louisiana. For further discussion see articles on Jazz, New orleans, New Orleans music, Swamp Pop, and Zydeco. louis moreau Gottschalk integrated Creole folk music into his compositions. Well-known Creole musicians include ...

[dB]

A logarithmic unit used for expressing the difference in level between sounds of different intensity or electrical signals of different power. It is related entirely to the ratio of the two quantities. If two signals have intensities I₁ and I₂ then their intensity ratio (in dB) is 10 log₁₀ (I₂/I₁). Differences in level expressed in decibels may be added and subtracted. The intensity level (IL) is defined by comparing the intensity (I) of the sound with a reference intensity (I₀), in which case IL = 10 log₁₀ (I/I₀). I₀ is normally taken as 10^-¹² Wm^-², corresponding approximately to the lower limit of human hearing. Although the logarithmic intensity level corresponds more closely to the perceived loudness of a sound than would a linear scale, loudness is not directly proportional to intensity level. In fact, for a pure tone, an increase of 10 dB gives rise to a doubling of perceived loudness, corresponding roughly to one step in the musical dynamic (e.g. ...