CD review: Auditory brainteasers
Mar 1, 1996 12:00 PM, By Patrick Bell
Diana Deutsch, Musical Illusions and Paradoxes, Philomel Records, compact disc, 42:21, 1995, $14.95. Two years ago, I sang in the chorus of a production of Verdi's Aida. Did the audience notice Radames' slightly off-pitch high notes? Did the flutist in the orchestra hear the notes as flat or sharp? Did the person in the last row of the balcony hear the same perfect harmony in Amneris and Aida's duet that I did? Psychologist Diana Deutsch, based at the University of California at San Diego, explores differences in musical interpretation and perception in a fascinating compact disc, Musical Illusions and Paradoxes.
Deutsch, a leading researcher of the brain's musical abilities, has long been documenting the often bizarre and inaccurate conclusions our auditory systems make. On her new disc, Deutsch guides the listener through a series of musical illusions and experiments illustrating her conclusion that wide perceptual discrepancies occur in the brain's interpretation of even the simplest musical patterns.
Deutsch begins with an octave illusion. Two tones spaced an octave apart are alternated repeatedly in the listener's headphones. The right ear receives the high tone and the left ear the low tone. Strangely, what seems to be a straightforward musical pattern is almost never heard correctly. Some subjects report hearing only a single tone; others hear complex patterns of alternating pitches in each headphone. The brain's willingness to combine tones is evident in its acceptance of an operatic singer's vibrato. The singer is actually producing a tone that hovers slightly above and below a pitch core, but the overall perception is of a perfectly tuned note. Stranger still is her discovery that right-handed and left-handed people tend to hear this illusion differently. Right-handers most often hear the high tone in the right ear, but left-handers vary in their perception of the tone's location. Auditory organization differs markedly between the two groups.
Next, the listener is led through illusions using simple major scales, chromatic scales and glissando, or the gliding up and down of the pitch scale. Here, too, you will be amazed at your own misperceptions and false conclusions. Two different melodies appear to be one. What seems to be a descending scale is actually ascending. Your left ear may interpret the exact opposite of your right.
In her research, Deutsch has examined the brain's ability to focus on minute sounds buried in an onslaught of noise from its surroundings. The brain organizes individual sounds through directional grouping and division of tones by high and low pitch. Because high tones do not travel as far as low tones, the brain can misinterpret the location of a sound's source.
Deutsch devotes a large part of the disc to a tritone paradox illustrating how the brain can misinterpret movement of pitch up and down the scale. A tritone is a pair of tones a half octave apart. When these tritones are played, listeners report contradictory pitch movement. Some believe the second note is higher on the pitch scale; others report a descending note. For example, the brain is able to identify accurately the notes C and F# but not whether the notes are high or low in relation to each other.
Deutsch includes a blank chart in the CD's accompanying booklet for the listener to chart his own perceptions. Amazing discrepancies appear when compared to the page showing which patterns were actually played. Although I have had years of ear training and professional vocal instruction, my answers were often incorrect. This experiment supports Deutsch's theory that all people possess a latent form of absolute or perfect pitch. This involuntary adherence to an innate pitch class circle allows the brain to be fooled.
The final portion of the disc is a Mysterious Melody. The listener hears the notes of a famous nursery rhyme. Each note is played in a different octave. Confused, the brain is unable to interpret the melody. After hearing the tune in one octave, the brain can analyze the multi-octave rendition upon a second attempt. This experiment illustrates that the brain remembers the relationship between notes when identifying a familiar melody and not the exact notes themselves. This also helps explain why modern music is often difficult to interpret and not an immediately enjoyable experience. These new patterns assault and contradict the brain's ingrained knowledge.
Musical Illusions and Paradoxes is both entertaining and disconcerting. I was amazed by my own misperceptions and delighted when I was able to accurately identify the musical patterns meant to trick me. However, I was left somewhat disturbed, wondering if throughout my life I have been hearing what Verdi and Britten intended or whether I am missing some crucial nuance closed to me because of my own physiology. Of course, perhaps fortunately, I'll never know. For information about ordering this CD, circle (260) on Rapid Facts Card.
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