Thomas D. Rossing

Spin‐Wave Resonance in Thin Films at Oblique Angles

Spin‐wave spectra in thin Permalloy films have been observed as the angle between the applied field and the film is varied from 0 to 90 degrees. The applied field corresponding to the main resonance peak falls very close to its calculated value for all angles. At some critical angle the spin‐wave spectrum collapses to a single peak. The observed critical angle is very near the angle at which the resonance frequency becomes independent of small changes in the magnetization, which supports a dynamic‐pinning model. The separation between the main peak and the subsidiary peaks reaches a maximum at an angle slightly less than the critical angle and drops sharply as the critical angle is approached. At no angle does the wavelength of the spin waves appear to be a submultiple of the film thickness as would be expected if the surface spins were completely pinned.As the angle between the applied field and the film increases from 0, the linewidth increases and reaches a maximum near 80°. Beyond this angle the linew...

Guitars and Lutes

The modern six-string guitar is a descendant of the sixteenth-century Spanish vihuela, which has its roots in antiquity. Although Boccherini and other composers of the eighteenth century included the guitar in some of their chamber music, the establishment of the guitar as a concert instrument took place largely in the nineteenth century. Fernando Sor (1778–1839) was the first of a long line of Spanish virtuosos and composers for the guitar.

Percussion Musical Instruments

Percussion instruments are an important part of every musical culture. Although they are probably our oldest musical instruments (with the exception of the human voice), there has been less research on the acoustics of percussion instruments, as compared to wind or string instruments. Quite a number of scientists, however, continue to study these instruments.

Steel pan developments

The Caribbean steel pan is likely the single most significant new acoustic musical instrument of the 20th Century. Some major developments incorporated by Felix Rohner of Panart have led to important instrument modifications. Among the differences to be discussed are as follows: using specified steel alloys in the sheet metal to replace commercial 55 Gal drums, sinking the pan in a press rather than by hand, surface hardening the playing surface in a nitride bath, dispensing with chiseled note section boundaries, adding a central dome to each note section, replacing the pan by a Hang (a lap-held instrument played by hand), and finally an additional air volume enclosed, to enhance low frequency resonances (the Gubal).The Caribbean steel pan is likely the single most significant new acoustic musical instrument of the 20th Century. Some major developments incorporated by Felix Rohner of Panart have led to important instrument modifications. Among the differences to be discussed are as follows: using specified steel alloys in the sheet metal to replace commercial 55 Gal drums, sinking the pan in a press rather than by hand, surface hardening the playing surface in a nitride bath, dispensing with chiseled note section boundaries, adding a central dome to each note section, replacing the pan by a Hang (a lap-held instrument played by hand), and finally an additional air volume enclosed, to enhance low frequency resonances (the Gubal).

Introduction to Acoustics

This brief introduction may help to persuade the reader that acoustics covers a wide range of interesting topics. It is impossible to cover all these topics in a single handbook, but we have attempted to include a sampling of hot topics that represent current acoustical research, both fundamental and applied.

A Brief History of Acoustics

Although there are certainly some good historical treatments of acoustics in the literature, it still seems appropriate to begin a handbook of acoustics with a brief history of the subject. We begin by mentioning some important experiments that took place before the 19th century. Acoustics in the 19th century is characterized by describing the work of seven outstanding acousticians: Tyndall, von Helmholtz, Rayleigh, Stokes, Bell, Edison, and Koenig. Of course this sampling omits the mention of many other outstanding investigators.

Psalteries and Zithers

The terms psaltery and zither are somewhat interchangeable. Both denote string instruments with strings that span the length of the sound box and sound board. From a musicological classification viewpoint, psalteries belong in the zither family of instruments, which also includes Appalachian dulcimers, autoharps, and hammered dulcimers.

Mandolin Family Instruments

The mandolin family of instruments consists of plucked chordophones, each having eight strings in four double courses. With the exception of the mandobass, the courses are tuned in intervals of fifths, as are the strings in violin family instruments. The soprano member of the family is the mandolin, tuned G3-D4-A4-E5. The alto member of the family is the mandola, tuned C3-G3-D4-A4. The mandola is usually referred to simply as the mandola in the USA, but is called the tenor mandola in Europe. The tenor member of the family is the octave mandolin, tuned G2-D3-A3-E4. It is referred to as the octave mandolin in the USA, and as the octave mandola in Europe. The baritone member of the family is the mandocello, or mandoloncello, tuned C2-G2-D3-A3. A variant of the mandocello not common in the USA is the five-course liuto moderno, or simply liuto, designed for solo repertoire. Its courses are tuned C2-G2-D3-A3-E4. A mandobass was also made by more than one manufacturer during the early twentieth century, though none are manufactured today. They were fretted instruments with single string courses tuned E1-A1-D2-G2. There are currently a few luthiers making piccolo mandolins, tuned C4-G4-D5-A5.