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Auditory Illusion
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. Humans are fairly susceptible to illusions, despite an innate ability to process complex stimuli. Confirmation bias is believed to be largely responsible for the inaccurate judgments that people make when evaluating information, given that humans typically interpret and recall information that appeals to their own biases. Amongst these misinterpretations, known as illusions, falls the category of auditory illusions. The brain uses multiple senses simultaneously to process information, spatial information is processed with greater detail and accuracy in vision than in hearing. Auditory illusions highlight areas where the human ear and brain, as organic survival tools, differentiate ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Optical Illusion
Within visual perception, an optical illusion (also called a visual illusion) is an illusion caused by the visual system and characterized by a visual perception, percept that arguably appears to differ from reality. Illusions come in a wide variety; their categorization is difficult because the underlying cause is often not clear but a classification proposed by Richard Gregory is useful as an orientation. According to that, there are three main classes: physical, physiological, and cognitive illusions, and in each class there are four kinds: Ambiguities, distortions, paradoxes, and fictions. A classical example for a physical distortion would be the apparent bending of a stick half immerged in water; an example for a physiological paradox is the motion aftereffect (where, despite movement, position remains unchanged). An example for a physiological fiction is an afterimage. Three typical cognitive distortions are the Ponzo illusion, Ponzo, Poggendorff illusion, Poggendorff, an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Deutsch's Scale Illusion
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. The illusion is produced by simultaneous ascending and descending major scales beginning in separate stereo channels with each successive note being switched to the opposite channel. With the left channel: C'-D-A-F--A-D-C'; and the right: C-B-E-G-E-B-C; the ear hears both: C'-B-A-G--A-B-C'; and: C-D-E-F--E-D-C. The tones are equal-amplitude sine waves, and the sequence is played repeatedly without pause at a rate of four tones per second. When listening to the illusion over headphones, most right-handers hear a melody corresponding to the higher tones as on the right and a melody corresponding to the lower tones as on the left. When the earphone positions are reversed, the higher tones continue to appear to be coming from the right and the lower tones from the left ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Speech-to-song Illusion
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. Discovery and first experiment The illusion was discovered by Deutsch in 1995 when she was preparing the spoken commentary on her CD ‘Musical Illusions and Paradoxes'. She had the phrase ‘sometimes behave so strangely' on a loop, and noticed that after it had been repeated several times it appeared to be sung rather than spoken. Later she included this illusion on her CD ‘Phantom Words and other Curiosities' and noted that once the phrase had perceptually morphed into song, it continued to be heard as song when played in the context of the full sentence in which it occurred. Deutsch, Henthorn, and Lapidis examined the illusion in detail. They showed that when this phrase was heard only ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Deutsch Tritone Paradox
__NOTOC__ 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 va ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shepard Tone
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. Construction Each square in Figure 1 indicates a tone, with any set of squares in vertical alignment together making one Shepard tone. The color of each square indicates the loudness of the note, with purple being the quietest and green the loudest. Overlapping notes that play at the same time are exactly one octave apart, and each scale fades in and fades out so that hearing the beginning or end of any given scale is impossible. As a conceptual example of an ascending Shepard scale, the first tone could be an almost inaudible C4 (middle C) and a loud C5 (an octave higher). The next would be a slight ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pareidolia
Pareidolia (; ) is the tendency for perception to impose a meaningful interpretation on a nebulous stimulus, usually visual, so that one sees an object, pattern, or meaning where there is none. Common examples are perceived images of animals, faces, or objects in cloud formations, seeing faces in inanimate objects, or lunar pareidolia like the Man in the Moon or the Moon rabbit. The concept of pareidolia may extend to include hidden messages in recorded music played in reverse or at higher- or lower-than-normal speeds, and hearing voices (mainly indistinct) or music in random noise, such as that produced by air conditioners or fans. Scientists have taught computers to use visual clues to "see" faces and other images. Etymology The word derives from the Greek words ''pará'' (, "beside, alongside, instead f) and the noun ''eídōlon'' (, "image, form, shape"). The German word was used in articles by Karl Ludwig Kahlbaum—for example in his 1866 paper "" ("On Delusion ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Octave Illusion
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. First experiment The two tones used were pitched at 400 Hz and 800 Hz, corresponding roughly to G4 and G5 in modern pitch notation. Each tone was played for 250 ms before switching ears. No gaps were allowed between tones. Both tones were therefore always present during the experiment; only the ears perceiving the high and the low tone at any one time changed repeatedly. After the initial test, the headphones ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lossy Audio Compression
In information theory, data compression, source coding, or bit-rate reduction is the process of encoding information using fewer bits than the original representation. Any particular compression is either lossy or lossless. Lossless compression reduces bits by identifying and eliminating statistical redundancy. No information is lost in lossless compression. Lossy compression reduces bits by removing unnecessary or less important information. Typically, a device that performs data compression is referred to as an encoder, and one that performs the reversal of the process (decompression) as a decoder. The process of reducing the size of a data file is often referred to as data compression. In the context of data transmission, it is called source coding; encoding done at the source of the data before it is stored or transmitted. Source coding should not be confused with channel coding, for error detection and correction or line coding, the means for mapping data onto a signal. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Harmonic Series (music)
A harmonic series (also overtone series) is the sequence of harmonics, musical tones, or pure tones whose frequency is an integer multiple of a ''fundamental frequency''. Pitched musical instruments are often based on an acoustic resonator such as a string or a column of air, which oscillates at numerous modes simultaneously. At the frequencies of each vibrating mode, waves travel in both directions along the string or air column, reinforcing and canceling each other to form standing waves. Interaction with the surrounding air causes audible sound waves, which travel away from the instrument. Because of the typical spacing of the resonances, these frequencies are mostly limited to integer multiples, or harmonics, of the lowest frequency, and such multiples form the harmonic series. The musical pitch of a note is usually perceived as the lowest partial present (the fundamental frequency), which may be the one created by vibration over the full length of the string or air c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Missing Fundamental
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 (perhaps with a different timbre) even if the fundamental frequency is missing from a tone. For example, when a note (that is not a pure tone) has a pitch of 100 Hz, it will consist of frequency components that are integer multiples of that value (e.g. 100, 200, 300, 400, 500.... Hz). However, smaller loudspeakers may not produce low frequencies, and so in our example, the 100 Hz component may be missing. Nevertheless, a pitch corresponding to the fundamental may still be heard. Explanation A low pitch (also known as the pitch of the missing fundamenta ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Illusory Discontinuity
Illusory discontinuity is an auditory illusion in which a continuous ongoing sound becomes inaudible during a brief, non-masking noise. The illusion is perceived only by some listeners, but not by others, reflecting individual variation in hearing abilities. It has been estimated that among young adults 24% are susceptible to illusory discontinuity.Vinnik E, Itskov PM, Balaban E (2011).Individual differences in sound-in-noise perception are related to the strength of short-latency neural responses to noise" PLoS One. 6(2): e17266. . The most susceptible listeners describe their sensations in terms of the sound actually containing a physical gap. The illusory discontinuity is strongest when the interrupting sound is short (50 ms). Longer sounds elicit weaker illusory discontinuity; this effect may be related to better auditory segregation. Relation to other auditory illusions Illusory discontinuity is antagonistic with illusory continuity of tones (auditory filling-in). ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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