The Experts below are selected from a list of 57 Experts worldwide ranked by ideXlab platform
Andrei Gabrielov - One of the best experts on this subject based on the ideXlab platform.
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Spectral loci of Sturm--Liouville operators with polynomial potentials
arXiv: Spectral Theory, 2013Co-Authors: Alexandre Eremenko, Andrei GabrielovAbstract:We consider differential equations -y"+P(z,a)y=Ey, where P is a polynomial of the independent variable z depending on a parameter a. The Spectral Locus is the set of (a,E) such that the equation has a non-trivial solution tending to zero on two fixed rays in the complex plane. We study the topology of the Spectral loci for polynomials P of degree 3 or 4.
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quasi exactly solvable quartic real algebraic Spectral Locus
Journal of Physics A, 2012Co-Authors: Alexandre Eremenko, Andrei GabrielovAbstract:We describe the real quasi-exactly solvable Spectral Locus of the PT-symmetric quartic using the Nevanlinna parametrization.
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Two-parametric PT-symmetric quartic family
Journal of Physics A, 2012Co-Authors: Alexandre Eremenko, Andrei GabrielovAbstract:We describe a parametrization of the real Spectral Locus of the two-parametric family of PT-symmetric quartic oscillators. For this family, we find a parameter region where all eigenvalues are real, extending the results of Dorey et al (2007 J. Phys. A: Math Theor. 40 R205–83) and Shin (2005 J. Phys. A: Math. Gen. 38 6147–66; 2002 Commun. Math. Phys. 229 543–64).
Punita G Singh - One of the best experts on this subject based on the ideXlab platform.
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Perception of rhythm by children in multitimbral, multimetric contexts
Journal of the Acoustical Society of America, 1999Co-Authors: Punita G SinghAbstract:Perception of meter by children aged 6 to 12 was studied using sequences of 12 tones as stimuli. Either no accents, or physical accents at positions implying triple, quadruple, or both meters were provided by changing the Spectral Locus of four harmonics n, n+1, n+2, n=3, of tones Ln (where n=2 or 6) or the rise/decay times of their temporal envelopes (95+5 ms, vs 5+95 ms). Listeners reported if they perceived a triple, quadruple, or ambiguous meter, or no accents at all. Children were easily able to perceive the metrical structure of sequences with accents on triple or quadruple meter positions alone. Mixed meters were hard to parse in a single‐timbre context. In mixed sequences with accents provided by different timbre features at quadruple and triple meter positions, listeners tended to follow the meter implied by tones L2 rather than L6. Temporal envelope variables were not effective in facilitating parsing of mixed meters. Results indicate that young listeners are similar to adults in using timbral i...
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An investigation of different timbral attributes as markers determining metrical structure
Journal of the Acoustical Society of America, 1998Co-Authors: Punita G SinghAbstract:Timbre attributes such as Spectral Locus, Spectral density, and temporal envelope slope were studied to determine their relative effectiveness as accent markers defining metrical structure. Complex‐tone sequences comprising 12 tones were used as stimuli with points of timbre change at positions implying a triple meter, quadruple meter, compound meter (both triple and quadruple), or unaccented sequences with no timbre changes. Tones at accented positions were made to differ from the rest by using different Spectral densities (1, 2, 4, or 8 harmonic components), by changing the Locus of components, and by changing the slopes of a two‐part temporal amplitude envelope. Listeners were asked to report if the sequence had a triple meter, quadruple meter, ambiguous meter, or no meter. Results thus far indicate that each of the timbre markers used is individually capable of bestowing metrical structure on a sequence. However, when competing cues exist to offer alternative interpretations of meter, more dense spect...
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influence of Spectral Locus and f0 changes on the pitch and timbre of complex tones
Journal of the Acoustical Society of America, 1992Co-Authors: Punita G Singh, Ira J HirshAbstract:Harmonic complex tones comprising components in different Spectral regions may differ considerably in timbre. While the pitch of ‘‘residue’’ tones of this type has been studied extensively, their timbral properties have received little attention. Discrimination of F0 for such tones is typically poorer than for complex tones with ‘‘corresponding’’ harmonics [A. Faulkner, J. Acoust. Soc. Am. 78, 1993–2004 (1985)]. The F0 DLs may be higher because timbre differences impair pitch discrimination. The present experiment explores effects of changes in Spectral Locus and F0 of harmonic complex tones on both pitch and timbre. Six normally hearing listeners indicated if the second tone of a two‐tone sequence was: (1) same, (2) higher in pitch, (3) lower in pitch, (4) same in pitch but different in ‘‘something else,’’ (5) higher in pitch and different in ‘‘something else,’’ or (6) lower in pitch and different in ‘‘something else’’ than the first. (‘‘Something else’’ is assumed to represent timbre.) The tones varied ...
Alexandre Eremenko - One of the best experts on this subject based on the ideXlab platform.
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Spectral loci of Sturm--Liouville operators with polynomial potentials
arXiv: Spectral Theory, 2013Co-Authors: Alexandre Eremenko, Andrei GabrielovAbstract:We consider differential equations -y"+P(z,a)y=Ey, where P is a polynomial of the independent variable z depending on a parameter a. The Spectral Locus is the set of (a,E) such that the equation has a non-trivial solution tending to zero on two fixed rays in the complex plane. We study the topology of the Spectral loci for polynomials P of degree 3 or 4.
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quasi exactly solvable quartic real algebraic Spectral Locus
Journal of Physics A, 2012Co-Authors: Alexandre Eremenko, Andrei GabrielovAbstract:We describe the real quasi-exactly solvable Spectral Locus of the PT-symmetric quartic using the Nevanlinna parametrization.
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Two-parametric PT-symmetric quartic family
Journal of Physics A, 2012Co-Authors: Alexandre Eremenko, Andrei GabrielovAbstract:We describe a parametrization of the real Spectral Locus of the two-parametric family of PT-symmetric quartic oscillators. For this family, we find a parameter region where all eigenvalues are real, extending the results of Dorey et al (2007 J. Phys. A: Math Theor. 40 R205–83) and Shin (2005 J. Phys. A: Math. Gen. 38 6147–66; 2002 Commun. Math. Phys. 229 543–64).
Ira J Hirsh - One of the best experts on this subject based on the ideXlab platform.
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influence of Spectral Locus and f0 changes on the pitch and timbre of complex tones
Journal of the Acoustical Society of America, 1992Co-Authors: Punita G Singh, Ira J HirshAbstract:Harmonic complex tones comprising components in different Spectral regions may differ considerably in timbre. While the pitch of ‘‘residue’’ tones of this type has been studied extensively, their timbral properties have received little attention. Discrimination of F0 for such tones is typically poorer than for complex tones with ‘‘corresponding’’ harmonics [A. Faulkner, J. Acoust. Soc. Am. 78, 1993–2004 (1985)]. The F0 DLs may be higher because timbre differences impair pitch discrimination. The present experiment explores effects of changes in Spectral Locus and F0 of harmonic complex tones on both pitch and timbre. Six normally hearing listeners indicated if the second tone of a two‐tone sequence was: (1) same, (2) higher in pitch, (3) lower in pitch, (4) same in pitch but different in ‘‘something else,’’ (5) higher in pitch and different in ‘‘something else,’’ or (6) lower in pitch and different in ‘‘something else’’ than the first. (‘‘Something else’’ is assumed to represent timbre.) The tones varied ...
Miroslav Dohnal - One of the best experts on this subject based on the ideXlab platform.
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New Lmn colour space
2020Co-Authors: Miroslav DohnalAbstract:In this paper is presented a new HS chromaticity diagram for 2-degree observer with more linear colour distribution. Both, the Spectral Locus and curve of purple colours generate unity circle - the HS diagram. By using the CIE lightness L as the third dimension, the Lmn colour space is generated. This new colour space is embedded into cylinder radius of 100 (it stands for chroma) and height of 100 (it stands for lightness). If n is plotted against m, the points in resulting Lmn-space are not uniquely related to chromaticity because their position depends on the value of L. The colours of all object-colour stimuli fall within this cylinder boundary. The spectrum Locus of the monochromatic stimuli is generally well outside the boundary of object-colour stimuli.
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The HS chromaticity diagram and the Lmn colour space
2006Co-Authors: Miroslav DohnalAbstract:In this paper a new HS chromaticity diagram for 10-degree observer with more linear colour distribution is presented. Both, the Spectral Locus and curve of purple colours generate unity circle -the HS diagram. By using the CIE lightness L as the third dimension, the Lrnn colour space is generated. This new colour space is embedded into cylinder radius of 100 (it stands for chroma) and height of 100 (it stands for lightness). If n is plotted against m the points in resulting Lmn-space are not uniquely related to chromaticity because their position depends on the value of L. The colours of all object-colour stimuli fall within this cylinder boundary. The spectrum Locus of the monochromatic stimuli is generally well outside the boundary of object-colour stimuli.