Andrew Piacsek

Central Washington University | CWU · Department of Physics

No PDF available ABSTRACT Alvin Lucier’s seminal 1969 composition and recording, “I Am Sitting in a Room” provides a fascinating and engaging tool for students to improve their understanding of room acoustics, as well as their skills in analyzing spectral data. This meta-composition, in which Lucier’s description of the process plays an essential r...

No PDF available ABSTRACT Hands-on activities are a valuable component of any introductory course in physical science, especially a course in musical acoustics that attracts students who are not majoring in a physical science. Tasks that require active engagement, both physical and cognitive, have been shown to improve retention of new concepts [Am...

No PDF available ABSTRACT It has been previously demonstrated that resonance frequencies of fluid-filled shells of simple geometry are shifted in proportion to fluid pressure [J.Acoust. Soc. Am. 131, EL506 (2012)]. We investigate the applicability of this approach for measuring changes of intracranial pressure in ovine skulls. A catheter inserted t...

No PDF available ABSTRACT It is a commonly stated belief among violin players and luthiers that new violins require a period of “playing in” for the tone to develop. Several studies have worked towards an answer to this question, such as measuring the change in tone according to the human ear or the vibrational response of stimulated wood. As the e...

Knowledge of measurement uncertainty is essential for any experiment that tests a causal relationship among two or more variables. We have developed a method for quantifying the expected range of deviation among repeated measurements of the impulse response of violins. We measure input mobility by tapping the bridge of a violin with a small modal i...

No PDF available ABSTRACT The field of musical acoustics encompasses all aspects of the design, construction, and performance of musical instruments (including the voice), as well as the physical and cultural environment in which they are played, with the goal of understanding how these elements contribute, separately or together, to the acoustic c...

No PDF available ABSTRACT Acoustic absorption of the low to mid-frequency range of human speech (80 to 800 Hz) is important for open office environments and can be achieved with resonant absorbers. However, traditional Helmholtz Resonators (HRs) are not an efficient solution because of the large dimensions required and their limited acoustic perfor...

No PDF available ABSTRACT Physics of musical sound is a first-year undergraduate course at Central Washington University that has been offered for over 20 years. The course is normally taught in a studio classroom format that utilizes peer instruction. Over the past few years, much of the course content and many of the exercises have been adapted t...

No PDF available ABSTRACT There is a widely accepted belief among luthiers and performers that consistent playing of stringed instruments, especially in the violin and lute families, is associated with improved sound and playability. Because it is thought that a new instrument needs to be played for some time in order to achieve its performance pot...

No PDF available ABSTRACT This paper describes the design process of a low-frequency sound absorptive panel composed of differently tuned Helmholtz Resonators. Given the size and fabrication constraints relevant for applications in the building sector, we focus on cylindrical and spiral resonators with embedded necks that are space-efficient and ca...

No PDF available ABSTRACT As the fruits of science and technology have permeated nearly every facet of modern life, and public policy decisions increasingly rely on knowledge created by the scientific process, there is growing concern that a deficiency of scientific literacy contributes to poor decisions in both private and public spheres. The ASA,...

No PDF available ABSTRACT This presentation describes the challenges, opportunities, and lessons learned in the selection and use of textbooks for a 10-week course in acoustics for undergraduate physics majors at the junior or senior level at Central Washington University. This course emphasizes both theoretical and experimental skills; topics incl...

Vibration measurements of a spherical aluminum shell (6 in. diameter) filled with water show that the resonance frequencies of the shell shift higher or lower with increasing water pressure, depending on the specific mode of vibration. For a given mode, the rate of frequency shift with pressure change Δf/Δp is approximately linear for gauge pressur...

The Force Concept Inventory is a widely used multiple-choice test that enables physics educators to assess the ability of students to apply basic concepts associated with Newton’s laws and to identify specific misconceptions held by students. When administered at the beginning of a course in introductory physics, as well as at the end, the FCI prov...

Computer simulations of physical phenomena, with graphical output, have long been used to enable visualizations of processes that are inherently invisible, such as sound wave propagation, or that operate on time scales that make direct observation difficult. For students struggling to make sense of an abstract physical concept, such as the relation...

We report on measurements recently made at the Wild Horse wind farm, near Ellensburg, WA, as part of short experiment to evaluate a device sensitive to acoustic particle velocity. Measurements were made at range of approximately 60 m, directly in front of (facing) a turbine, at a height 1.5 m above ground using a sound level meter (SLM) and vector...

At many primarily undergraduate institutions, and some PhD-granting universities, science and engineering faculty are expected to provide research experiences for undergraduates. One of the biggest challenges for faculty who supervise undergraduate research is preparing students to work productively with some degree of independence. In addition to...

“Why do I have to take this math course—when will I ever use this stuff?” and “I could never be a scientist—I'm terrible at math.” These statements are familiar to educators the world over, much to our frustration... and to the detriment of society's goals of being scientifically and mathematically literate and having a large and diverse population...

A combined classroom/lab activity is described that employs a modified Interrupted Case Study approach to reinforce concepts of standing waves, superposition, and musical intervals. Students work cooperatively, with guidance from the instructor, to investigate the behavior of a plucked string. The activity is structured as a sequence of tasks that...

First described by Fuller and Snelson in the mid-twentieth century, tensegrity structures comprise a network of elements that alternately support compression (struts) and tension (cables). When the cable elements are pre-stressed, tensegrity structures maintain a stable form, regardless of orientation. If external forces are applied, the structure...

A popular and (perhaps) provocative demonstration in an introductory course on acoustics and vibration involves asking students to predict what happens to the tap tone of a wine glass when liquid is added. Although their predictions are often incorrect, students readily accept the explanation of mass loading for why the pitch decreases, having alre...

The basic conflict between scientist and journalist is that each wants to tell a story-but not necessarily the same story. Can they agree on a version that grabs and holds the attention of most people but is still true to the science? Despite the risks of being portrayed inaccurately, should researchers make an effort to talk to the press? This tal...

Community-based wind power companies provide subscriptions to individual homeowners and businesses for power generated by a locally installed turbine. Typically, such turbines are of an intermediate size, such as the Vestas V20 120-kW turbines operated by the Cascade Community Wind Company in several locations within Washington state. This model tu...

Computer-based investigations of the nature of formants and their role in characterizing vowel sounds and the timbre of musical instruments will be described. One version of this activity requires students to obtain detailed spectra of different vowel sounds, measure relative amplitudes of harmonics in the recorded sounds, and perform additive synt...

Community-based inquiry (CBI) is an approach to providing an active and collaborative learning environment for students in a science classroom. Inquiry-based learning has been shown to improve critical thinking skills, as well as retention of new concepts [Quitadamo et al., Life Sci. Educ. 7, 327-337 (2008)]. For a typical CBI project, all students...

The Nonlinear Progressive-wave Equation (NPE) is one of three numerical models of focused sonic boom prediction being validated as part of the Superboom Caustic Analysis and Measurement Project (SCAMP). Formulated in the time domain, the NPE begins with a far-field acoustic signature and propagates it into the region with caustics, accounting for n...

A possible method for noninvasively monitoring changes in intracranial pressure is to measure changes in skull resonance frequencies. Recent measurements of the vibrational response of a spherical aluminum shell clearly demonstrate that resonance frequencies shift higher as the internal pressure is increased [Piacsek et al, J. Acous. Soc. Am, 131,...

At Central Washington University, "Physics of Musical Sound" (PHYS103) is an introductory level course that satisfies a General Education Breadth requirement in the lab-based science category. Enrollment is capped at 40 students, of which 10-15 are typically music education majors. From 1998 to 2010, this five-credit course was taught in a traditio...

Measurements of the vibrational response of a spherical aluminum shell subject to changes in the interior pressure clearly demonstrate that resonance frequencies shift higher as the pressure is increased. The frequency shift appears to be smaller for longitudinal modes than for bending wave modes. The magnitude of frequency shift is comparable to a...

The nonlinear progressive wave equation (NPE) [McDonald and Kuperman, J. Acoust. Soc. Am. 81, 1406-1417 (1987)] is expressed in a form to accommodate changes in the ambient atmospheric density, pressure, and sound speed as the time-stepping computational window moves along a path possibly traversing significant altitude differences (in pressure sca...

Numerical simulations provide a valuable tool for students to investigate complicated behavior found in many applications of acoustics. Computational "experiments" can be conducted quickly for a large number of parameter values, enabling students to visualize abstract quantities and to grasp causal relationships not easily recognized when looking a...

A finite?element model of the vibrational response of fluid?filled shells with arbitrary shape and composition has been developed using the COMSOL multi?physics modeling package. The user can specify the properties of the fluid inside the shell including the static pressure. The shell is surrounded by air, which is enclosed by a perfectly matched l...

The resonance frequencies of a spherical aluminum shell (radius 3.0 in., thickness 1/8 in.) filled with water have been measured for several different values of static water pressure. It is found that a pressure increase of 100 psi causes resonance frequencies associated with axisymmetric bending modes to shift higher by about 0.15%, consistent wit...

The high-angle formulation of the nonlinear progressive wave equation model (NPE2) [McDonald, Wave Motion 31, 165-171 (2000)] has been adapted for atmospheric propagation and is used to perform numerical simulations of sonic boom propagation through atmospheric turbulence. Turbulence is incorporated into the model as perturbations of the local ambi...

The nonlinear progressive wave equation (NPE) model [McDonald and Kuperman, J. Acoust. Soc. Am. 81, 1406 (1987)] is modified to simulate sonic boom physics in a stratified atmosphere using a wave-following window whose dimensions are much less than atmospheric scale heights. (The NPE was originally formulated for time domain weak shock propagation...

Students can learn about standing waves in rooms as they recreate the classic 1970 recording by Lucier, “I Am Sitting in a Room”. In this work, the composer records himself describing the process in which he is engaged. The approximately 1‐min recording of his speech is then played back and re‐recorded in the same acoustic environment (an unspecifi...

This presentation provides an overview of the subject of numerical modeling of weak shock propagation, with the aim of providing context for subsequent talks in this session. First is a brief history of analytical approaches to the problem of weak shocks in both one and two dimensions, emphasizing the characteristic physical behavior of the solutio...

Many physics departments offer a ``Physics of Music'' course that is intended for non-majors. This topic appeals to a broad cross-section of students, in part because people recognize that it represents a rare window into the abstruse world of physics from a familiar vantage point. Conversely, physics educators recognize that an interdisciplinary c...

To better understand the mechanisms by which atmospheric turbulence alters sonic boom rise times and peak overpressures, numerical calculations of sonic boom propagation through atmospheric turbulence have been performed using the NPE time domain model. Turbulence is incorporated into the model as a perturbation of the ambient sound speed that has...

In recent years, science pedagogy at all levels has embraced active student learning, in which students are engaged in the process of discovery, rather than passively receiving information. One of the benefits of active learning in a science curriculum is that students have an opportunity to emulate scientists in their approach to producing knowled...

A 2-D nonlinear time domain computational model of sonic boom propagation has been modified to incorporate the e!ects of atmospheric turbulence. This model, based on the Nonlinear Progressive wave Equation (NPE) of McDonald and Kuperman, is used to prop- agate N-waves from the upper turbulent boundary layer (TBL) to the ground through di!erent turb...

The Nonlinear Progressive wave Equation (NPE) is modified to include a turbulence representation based upon temperature fluctuations. The turbulence is composed of the sum of 600 Fourier modes based on a modified von Kármán spectrum with an outer length scale of 100 m and an inner length scale of .001 m. Variations in temperature induce variations...

How is it that we can recognize familiar vowel sounds regardless of who is speaking? How does my voice compare to your voice? The acoustics laboratory exercise described here appeals to our natural curiosity about everyday phenomena and about ourselves. In the first part, students use a PC equipped with a built?in microphone and easy?to?use sound a...

There is a growing interest in resolving the question of whether, and how, the act of playing a stringed instrument (in the violin and guitar families) improves its sound and playability over time. Although generally accepted by musicians, the causal connection is difficult to test due to the very large number of potentially relevant parameters, bo...

A set of interactive computer animations of acoustic phenomena was created using the Java‐based PHYSics appLETS (or physlets) developed at Davidson College [Christian and Belloni, 2001]. These animations allow the user to adjust certain parameters of a modeled system and view—in real time—the corresponding change in the physical behavior of the sys...

Invented by R. Buckminster Fuller and Kenneth Snelson between 1948 and 1961, tensegrity structures consist of stiff rods connected to flexible strings such that no rod is joined to any other rod. A prestressed tensegrity structure, in which all the strings are under tension, maintains a distinct shape, deforming slightly under a load. For the prese...

As part of a National Science Foundation STEP grant to stimulate recruitment and improve retention of students in science, mathematics, and technology, several science faculty at Central Washington University developed a 2-week summer program for high school students entering their senior year. From June 23 to July 2, 2003, 13 high school juniors f...

It is a well-known dictum among players of stringed instruments that the tone of a new instrument improves with playing and that a fine instrument needs to be played if it is to maintain its optimum sound quality. This process is sometimes referred to as ``playing in'' an instrument. There is scant mention in the scientific literature, however, of...

In recent years, the desktop computer has acquired the signal processing and visualization capabilities once obtained only with expensive specialized equipment. With the appropriate A/D card and software, a PC can behave like an oscilloscope, a real-time signal analyzer, a function generator, and a synthesizer, with both audio and visual outputs. I...

The propagation and subsequent distortion of sonic booms with rippled wave fronts are investigated theoretically using a nonlinear time-domain finite-difference scheme. This work seeks to validate the rippled wave front approach as a method for explaining the significant effects of turbulence on sonic booms [A. S. Pierce and D. J. Maglieri, J. Acou...

Electric power production from wind turbines has increased substantially during the past few years due to the growing emphasis on renewable energy sources and more efficient wind turbine technology. Although modern turbines are significantly quieter than early models, wind farms that are proposed near residential areas generate concern about potent...

A fiber?optic probe (MTI?2000 Fotonic Sensor) is used by Central Washington University physics students to measure the peak displacement of such vibrating surfaces as acoustically driven wineglasses, parametrically shaken liquids, and soap films. This presentation will consist of a brief description of the fiber?optic measurement system, a discussi...

In support of the Comprehensive Test Ban, research is under way on the long range propagation of signals from nuclear explosions in deep underwater sound (SOFAR) channel. Initially our work at LLNL on signals in the source region considered explosions in or above deep ocean. We studied the variation of wave properties and source region energy coupl...

Finite?difference calculations of strong pulses propagating downslope in typical littoral environments were performed using the NPE program [B. E. McDonald and W. A. Kuperman, J. Acoust. Soc. Am. 81, 1406?1417 (1987)], modified to include a seabed depth that varies with range and which provides for a specification of sound?speed gradients in the bo...

In support of the Comprehensive Test Ban, research is underway on the long range propagation of signals from nuclear explosions in the deep underwater sound (SOFAR) channel. This first phase of our work at LLNL on signals in the source regions considered explosions in or above the deep (5000 m) ocean. We studied the variation of wave properties and...

In a classic paper treating the propagation of weak shocks, Whitham elucidated the process by which nonlinear effects would prevent rays within a concave portion of a shock front from intersecting, thereby avoiding a folded wavefront and associated caustics [G. B. Whitham, J. Fluid Mech. 1, 290?318 (1956)]. Whitham?s analysis neglected the effects...

In support of the Comprehensive Test Ban, research is underway on the long?range propagation of signals from nuclear explosions in the deep underwater sound (SOFAR) channel. Our work has emphasized the variation of wave properties and source region energy coupling as a function of height or depth of burst. Initial calculations on CALE, a two?dimens...

A time domain equation for nonlinear sound propagation that makes use of a narrow angle assumption is used to numerically simulate shock propagation through caustics. This formulation bears resemblence to the one-dimensional Burgers equation, but accounts for diffraction away from the primary axis of propagation. To implement this model on a comput...

A finite difference solution to an NPE‐like equation is used to study the linear and nonlinear behavior of focusing step shocks in regions where caustics are formed. The initial condition is a nominally plane step pulse with a hyperbolic tangent rise profile of thickness l sh ; the wavefront has a single ripple of length scale L wf, concave towards...

One strategy in the effort to explain features of observed sonic boom profiles that deviate from the classical N shape is to simulate, one a computer, the propagation of shock waves in an inhomogeneous medium. A time?marching finite?difference code is being developed by the author which employs a multidimensional explicit flux corrected transport s...

An alternative to the Pestorius–Anderson algorithm based on FFT concepts for nonlinear wave propagation with dissipation is one that makes explicit use of finite difference schemes. In a relatively recent study, Dey [Adv. Comp. Meth. Part. Diff. Eq. 6, 382–388 (1987)] presented and examined various finite difference schemes for solving Burgers’ equ...

The nonlinear progressive wave equation (NPE) model, developed by McDonald and Kuperman [J. Acoust. Soc. Am. 81, 1406–1417 (1987)] has been adapted for atmospheric propagation in order to model the effect of turbulence on the shape of sonic boom profiles. As a test of the efficacy of this adaption, the program was run with a relatively simple scena...

In a recent paper (AIAA‐90‐4031), Pierce and Sparrow have suggested that the prediction of the distortion of sonic booms by atmospheric turbulence can be carried out using modification of the Friedlander series theory that gives waveforms as a power series in time relative to wave onset. The present paper explores basic mathematical problems associ...

A discussion is given of some recent noise measurements on an apparatus where condensation occurs in an annular region. The possible dominant noise sources are discussed and assessed with the aid of data. The primary cause of noise is argued to be the unsteady flow in the condenser and this is attributed to large?scale cavitation effects. In the tu...