Glissando illusion

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The glissando illusion is an auditory illusion, created when a sound with a fixed pitch, such as a synthesized oboe tone, is played together with a sine wave gliding up and down in pitch, and they are both switched back and forth between stereo loudspeakers. The effect is that the oboe is heard as switching between loudspeakers while the sine wave is heard as joined together seamlessly, and as moving around in space in accordance with its pitch motion. Right-handers often hear the glissando as traveling from left to right as its pitch glides from low to high, and then back from right to left as its pitch glides from high to low.

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The effect was first reported and demonstrated by Diana Deutsch in Musical Illusions and Paradoxes, 1995.

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In music, a glissando is a glide from one pitch to another. It is an Italianized musical term derived from the French glisser, "to glide". In some contexts, it is distinguished from the continuous portamento. Some colloquial equivalents are slide, sweep, bend, smear, rip, lip, plop, or falling hail. On wind instruments, a scoop is a glissando ascending to the onset of a note achieved entirely with the embouchure.

Absolute pitch (AP), often called perfect pitch, is a rare ability of a person to identify or re-create a given musical note without the benefit of a reference tone. AP may be demonstrated using linguistic labeling, associating mental imagery with the note, or sensorimotor responses. For example, an AP possessor can accurately reproduce a heard tone on a musical instrument without "hunting" for the correct pitch.

<span class="mw-page-title-main">Shepard tone</span> Auditory illusion

A Shepard tone, named after Roger Shepard, is a sound consisting of a superposition of sine waves separated by octaves. When played with the bass pitch of the tone moving upward or downward, it is referred to as the Shepard scale. This creates the auditory illusion of a tone that seems to continually ascend or descend in pitch, yet which ultimately gets no higher or lower.

<span class="mw-page-title-main">Pitch (music)</span> Perceptual property in music ordering sounds from low to high

Pitch is a perceptual property of sounds that allows their ordering on a frequency-related scale, or more commonly, pitch is the quality that makes it possible to judge sounds as "higher" and "lower" in the sense associated with musical melodies. Pitch is a major auditory attribute of musical tones, along with duration, loudness, and timbre.

Auditory illusions are false perceptions of a real sound or outside stimulus. These false perceptions are the equivalent of an optical illusion: the listener hears either sounds which are not present in the stimulus, or sounds that should not be possible given the circumstance on how they were created.

<span class="mw-page-title-main">Missing fundamental</span>

A harmonic sound is said to have a missing fundamental, suppressed fundamental, or phantom fundamental when its overtones suggest a fundamental frequency but the sound lacks a component at the fundamental frequency itself. The brain perceives the pitch of a tone not only by its fundamental frequency, but also by the periodicity implied by the relationship between the higher harmonics; we may perceive the same pitch even if the fundamental frequency is missing from a tone.

<span class="mw-page-title-main">Combination tone</span>

A combination tone is a psychoacoustic phenomenon of an additional tone or tones that are artificially perceived when two real tones are sounded at the same time. Their discovery is credited to the violinist Giuseppe Tartini and so they are also called Tartini tones.

The octave illusion is an auditory illusion discovered by Diana Deutsch in 1973. It is produced when two tones that are an octave apart are repeatedly played in alternation ("high-low-high-low") through stereo headphones. The same sequence is played to both ears simultaneously; however when the right ear receives the high tone, the left ear receives the low tone, and conversely. Instead of hearing two alternating pitches, most subjects instead hear a single tone that alternates between ears while at the same time its pitch alternates between high and low.

<span class="mw-page-title-main">Tritone paradox</span> An auditory illusion perceived by some people to be rising in pich and by others to be falling

The tritone paradox is an auditory illusion in which a sequentially played pair of Shepard tones separated by an interval of a tritone, or half octave, is heard as ascending by some people and as descending by others. Different populations tend to favor one of a limited set of different spots around the chromatic circle as central to the set of "higher" tones. Roger Shepard in 1963 had argued that such tone pairs would be heard ambiguously as either ascending or descending. However, psychology of music researcher Diana Deutsch in 1986 discovered that when the judgments of individual listeners were considered separately, their judgments depended on the positions of the tones along the chromatic circle. For example, one listener would hear the tone pair C–F as ascending and the tone pair G–C as descending. Yet another listener would hear the tone pair C–F as descending and the tone pair G–C as ascending. Furthermore, the way these tone pairs were perceived varied depending on the listener's language or dialect.

<span class="mw-page-title-main">Square wave</span> Type of non-sinusoidal waveform

A square wave is a non-sinusoidal periodic waveform in which the amplitude alternates at a steady frequency between fixed minimum and maximum values, with the same duration at minimum and maximum. In an ideal square wave, the transitions between minimum and maximum are instantaneous.

Deutsch's scale illusion is an auditory illusion in which two series of unconnected notes appear to combine into a single recognisable melody, when played simultaneously into the left and right ears of a listener.

Diana Deutsch is a British-American psychologist from London, England. She's a professor of psychology at the University of California, San Diego, and is a prominent researcher on the psychology of music. Deutsch is primarily known for her discoveries in music and speech illusions. She also studies the cognitive foundation of musical grammars, which consists of the way people hold musical pitches in memory, and how people relate the sounds of music and speech to each other. In addition, she is known for her work on absolute pitch, which she has shown is far more prevalent among speakers of tonal languages. Deutsch is the author of Musical Illusions and Phantom Words: How Music and Speech Unlock Mysteries of the Brain (2019), the Psychology of Music, and also the compact discs Musical Illusions and Paradoxes (1995) and Phantom Words and Other Curiosities (2003).

<span class="mw-page-title-main">Beat (acoustics)</span> Term in acoustics

In acoustics, a beat is an interference pattern between two sounds of slightly different frequencies, perceived as a periodic variation in volume whose rate is the difference of the two frequencies.

<span class="mw-page-title-main">Sound</span> Vibration that travels via pressure waves in matter

In physics, sound is a vibration that propagates as an acoustic wave, through a transmission medium such as a gas, liquid or solid. In human physiology and psychology, sound is the reception of such waves and their perception by the brain. Only acoustic waves that have frequencies lying between about 20 Hz and 20 kHz, the audio frequency range, elicit an auditory percept in humans. In air at atmospheric pressure, these represent sound waves with wavelengths of 17 meters (56 ft) to 1.7 centimeters (0.67 in). Sound waves above 20 kHz are known as ultrasound and are not audible to humans. Sound waves below 20 Hz are known as infrasound. Different animal species have varying hearing ranges.

<span class="mw-page-title-main">Illusory conjunctions</span> Illusory conjunctions

Illusory conjunctions are psychological effects in which participants combine features of two objects into one object. There are visual illusory conjunctions, auditory illusory conjunctions, and illusory conjunctions produced by combinations of visual and tactile stimuli. Visual illusory conjunctions are thought to occur due to a lack of visual spatial attention, which depends on fixation and the amount of time allotted to focus on an object. With a short span of time to interpret an object, blending of different aspects within a region of the visual field – like shapes and colors – can occasionally be skewed, which results in visual illusory conjunctions. For example, in a study designed by Anne Treisman and Schmidt, participants were required to view a visual presentation of numbers and shapes in different colors. Some shapes were larger than others but all shapes and numbers were evenly spaced and shown for just 200 ms. When the participants were asked to recall the shapes they reported answers such as a small green triangle instead of a small green circle. If the space between the objects is smaller, illusory conjunctions occur more often.

The neuroscience of music is the scientific study of brain-based mechanisms involved in the cognitive processes underlying music. These behaviours include music listening, performing, composing, reading, writing, and ancillary activities. It also is increasingly concerned with the brain basis for musical aesthetics and musical emotion. Scientists working in this field may have training in cognitive neuroscience, neurology, neuroanatomy, psychology, music theory, computer science, and other relevant fields.

Psychoacoustics is the branch of psychophysics involving the scientific study of sound perception and audiology—how humans perceive various sounds. More specifically, it is the branch of science studying the psychological responses associated with sound. Psychoacoustics is an interdisciplinary field of many areas, including psychology, acoustics, electronic engineering, physics, biology, physiology, and computer science.

<span class="mw-page-title-main">Pitch circularity</span> Fixed series of tones that appear to ascend or descend endlessly in pitch

Pitch circularity is a fixed series of tones that are perceived to ascend or descend endlessly in pitch. It's an example of an auditory illusion.

Interindividual differences in perception describes the effect that differences in brain structure or factors such as culture, upbringing and environment have on the perception of humans. Interindividual variability is usually regarded as a source of noise for research. However, in recent years, it has become an interesting source to study sensory mechanisms and understand human behavior. With the help of modern neuroimaging methods such as fMRI and EEG, individual differences in perception could be related to the underlying brain mechanisms. This has helped to explain differences in behavior and cognition across the population. Common methods include studying the perception of illusions, as they can effectively demonstrate how different aspects such as culture, genetics and the environment can influence human behavior.

The speech-to-song illusion is an auditory illusion discovered by Diana Deutsch in 1995. A spoken phrase is repeated several times, without altering it in any way, and without providing any context. This repetition causes the phrase to transform perceptually from speech into song.

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See also

Shepard–Risset glissando: A different glissando-related musical illusion