Volume 6, Issue 3, July 2010
Index of content:
6(2010); http://dx.doi.org/10.1121/1.3488670View Description Hide Description
In viewing M. C. Escher's lithograph Ascending and Descending (shown on the front cover of this issue), we see monks plodding up and down an endless staircase—each monk will ultimately arrive at the place where he began his impossible journey. Our perceptual system insists on this interpretation, even though we know it to be incorrect. Our visual system opts for a simple interpretation based on local relationships within the figure, rather than choosing a complex, yet correct, interpretation that takes the entire figure into account. We observe that each stair that is one step clockwise from its neighbor is also one step downward, and so we perceive the staircase as eternally descending. In principle, we could instead perceive the figure correctly as depicting four sets of stairs that are discontinuous, and viewed from a unique perspective—however such a percept never occurs. This paper explores an analogous set of auditory figures that are composed of patterns that appear to ascend or descend endlessly in pitch. Here also, our perceptual system opts for impossible but simple interpretations, based on our perception of local motion in a particular direction—either upward or downward. These sound patterns are not mere curiosities; rather they provide important information concerning general characteristics of pitch perception.
6(2010); http://dx.doi.org/10.1121/1.3488664View Description Hide Description
Will listening to Radiohead make you smarter? Probably not. But according to noted Internet data miner Virgil Griffith, the typical Radiohead fan scores about 110 points higher on the Scholastic Aptitude Test (SAT) than the typical Grateful Dead fan (Fig. 1). Of course as we all know, correlation does not equal causation. But, to quote Aniruddh Patel music is a “transformative technology of the mind,” and we know that music does have a very real effect on skills outside the realm of air guitar. The quest to determine the mechanism for this transference of musical skills has already begun. In the Kraus lab at Northwestern University, the skills that interest us most are reading and speech‐in‐noise (SIN) perception. Significantly, musicians excel at these very activities. Our research has led us to measuring deep‐brain electroencephalograph (EEG) in response to a variety of complex stimuli, and we have found correlates in this subcortical activity to reading and listening‐innoise skills. A logical step was to look at the interaction between SIN perception and reading and the changes in biology brought about by active engagement with music.
6(2010); http://dx.doi.org/10.1121/1.3488666View Description Hide Description
Singing, or the act of producing musical sounds with the voice, is celebrated in every culture around the world. From the earliest point in infancy, humans have some knowledge of musical sounds, broadly defined—evidence for knowledge of musical attributes has been observed even in newborn infants. Sensitivities to pitch, key, and harmony are known to emerge from infancy to childhood and have been reported in many other cultures. Because of its prevalence among humans, the ability to make music has been posited as an innate human ability. Singing requires the coordination of auditory and motor networks and involves the perception and production of pitch and rhythm. People who have problems with singing, i.e., tone‐deaf people, provide an interesting model for studying brain networks involved in singing and how they might overlap with networks for speaking abilities. This overlap of neural resources recruited in singing and speaking is useful in therapeutic applications, where the loss of language function (a condition known as aphasia) can be rehabilitated using a treatment program known as Melodic Intonation Therapy. In this article, we will review current research in our lab on singing: what the ability entails, why some individuals lack singing ability, and how singing can be used to improve the well‐being of those afflicted by neurological disorders.
6(2010); http://dx.doi.org/10.1121/1.3488667View Description Hide Description
If you stare at a banjo hard enough, you can see two interacting, wavebearing systems; specifically, strings and a circular membrane. What's more, they are systems for which we can solve the equations of motion and thereby describe the propagation of structural vibrations; i.e., waves. At its lowest level of abstraction, the “simplified” banjo is basically two interacting vibrating systems: a plucked string and a circular membrane. The five‐string banjo is a little more complicated as it has six interacting systems—five strings and one membrane. The equations which describe the way waves travel in these systems, how they radiate sound, and how they interact are fairly straightforward. As banjo modeling gets more sophisticated, there are many such considerations which will become important, and with this will come more pressure to keep the model as simple a possible while retaining what you set out to discover. Why do we go to so much trouble to model the banjo? Partly to build better banjos or help people who fix or play banjos get a better sound by understanding how the various components of the instrument work together to produce the sound. More generally, we do this sort of thing (modeling) to build a better anything. This story describes the why and wherefore of analytical modeling.
6(2010); http://dx.doi.org/10.1121/1.3488668View Description Hide Description
The Acoustical Society of America meetings feature a popular new social function, the ASA Jam. The Jam offers an opportunity for members and their guests to play music in a friendly and improvisational setting, using provided equipment and instruments that are arranged in advance through the generous efforts of dedicated volunteers. The Jam extends the invitation to participate or simply, attend to all Society members and their guests.