Optimality of human acoustic perception of natural sounds, and violin acoustics elucidated with a non-corporeal musical instrument made by fully air-coupled finite-element-modeling of the Titian Stradivarius
By Weber’s Law, just-noticeable-differences of a stimulus grow in proportion to the stimulus. From hundreds of measurements of naturally scintillating environmental sound signals, Weber's law is found to be a consequence of attaining the minimum mean-square error, known as the Cramer-Rao lower...
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| Format: | Thesis |
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Massachusetts Institute of Technology
2024
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| Online Access: | https://hdl.handle.net/1721.1/153340 |
| _version_ | 1826192056251318272 |
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| author | Krishnadas, Arun |
| author2 | Makris, Nicholas C. |
| author_facet | Makris, Nicholas C. Krishnadas, Arun |
| author_sort | Krishnadas, Arun |
| collection | MIT |
| description | By Weber’s Law, just-noticeable-differences of a stimulus grow in proportion to the stimulus. From hundreds of measurements of naturally scintillating environmental sound signals, Weber's law is found to be a consequence of attaining the minimum mean-square error, known as the Cramer-Rao lower bound, and maximum Fisher information in intensity estimation. Remarkably, just-noticeable-differences in sound intensity from decades of psychophysical experiments with artificial sound, are also found to approximately attain the respective Cramer-Rao lower bounds on intensity resolution obtained from the natural sound intensity fluctuations we measured, indicating that they are approximately optimally adapted to environmental scintillation. This adaptation is also found to maximize general information reception and optimize pattern recognition via homomorphic variance-stabilizing transformation of natural signal-dependent intensity scintillation received to signal-independent noise perceived that can be canceled without loss of signal information. It is consistent with diverse natural processes in random wave generation converging to similar intensity scintillation statistics by the central limit theorem. Sensing resolution adapted to follow Weber's Law so provides quantifiable advantages to organisms, systems or machines that rely on auditory sensory perception with natural sound to survive or function effectively.
In the second part of this thesis, we look at music perception and build a non-corporeal instrument: a fully air-coupled finite-element-modeled Titian Stradivarius violin employing CT-scan reconstruction. The non-corporeal instrument is trained to play the first two measures of the Sonata No. 1 in G-minor, BWV 1001: II. Fuga. Allegro by Bach, using a constrained optimization approach. The musical piece played is found to be indistinguishable from Itzhak Perlman’s concert performance used to train the instrument. The non-corporeal violin allows us to study two new ways in which design changes may be perceived. Firstly we implement design modifications important to violin acoustics and show corresponding plucked and bowed string sounds. Secondly we look at how a violinist would compensate for these design modifications by altering their input actions to obtain the desired sound. The former is advantageous to violin makers who can experiment with changes without making them on their physical instrument. The latter provides a playability metric to classify violins similar to how a player might perceive them.
In addition to perception of violin sounds, we show acoustic features of a violin such as its efficiency as a measure of power entering the instrument to the power radiated as sound. This is found to vary from roughly 15\% in the male Baritone voice range to 25\% in the female Mezzo-Soprano and Soprano voice range before falling off to 15\% beyond. The consequences of these efficiency variations on player compensations for uniform sound across musical notes is shown. Additionally, we show the parts of a violin contributing to radiated sound: f-holes dominate radiation at the low frequencies near the Helmholtz resonance transitioning to a predominantly body-induced radiation at higher frequencies through the top plate. The non-corporeal violin also allows us to “see” the sound through a complete spatial characterization of acoustic pressures from the surface of the violin out to the far-field in three-dimensional space. The accuracy of our results are shown by validating against experimentally measured structural velocities in the entire spectral range of importance to violin radiation. Experimental matching so obtained is primarily a consequence of the air-coupling together with the implementation of instrument quality wood as an orthotropic viscoelastic material to capture elasticity and damping properties. The high impedance contrast approaches developed here can be applied to related acoustic problems involving geophysical, biological and naval structures in air, water and other fluid media. |
| first_indexed | 2024-09-23T09:05:37Z |
| format | Thesis |
| id | mit-1721.1/153340 |
| institution | Massachusetts Institute of Technology |
| last_indexed | 2024-09-23T09:05:37Z |
| publishDate | 2024 |
| publisher | Massachusetts Institute of Technology |
| record_format | dspace |
| spelling | mit-1721.1/1533402024-01-17T03:56:41Z Optimality of human acoustic perception of natural sounds, and violin acoustics elucidated with a non-corporeal musical instrument made by fully air-coupled finite-element-modeling of the Titian Stradivarius Krishnadas, Arun Makris, Nicholas C. Massachusetts Institute of Technology. Department of Mechanical Engineering By Weber’s Law, just-noticeable-differences of a stimulus grow in proportion to the stimulus. From hundreds of measurements of naturally scintillating environmental sound signals, Weber's law is found to be a consequence of attaining the minimum mean-square error, known as the Cramer-Rao lower bound, and maximum Fisher information in intensity estimation. Remarkably, just-noticeable-differences in sound intensity from decades of psychophysical experiments with artificial sound, are also found to approximately attain the respective Cramer-Rao lower bounds on intensity resolution obtained from the natural sound intensity fluctuations we measured, indicating that they are approximately optimally adapted to environmental scintillation. This adaptation is also found to maximize general information reception and optimize pattern recognition via homomorphic variance-stabilizing transformation of natural signal-dependent intensity scintillation received to signal-independent noise perceived that can be canceled without loss of signal information. It is consistent with diverse natural processes in random wave generation converging to similar intensity scintillation statistics by the central limit theorem. Sensing resolution adapted to follow Weber's Law so provides quantifiable advantages to organisms, systems or machines that rely on auditory sensory perception with natural sound to survive or function effectively. In the second part of this thesis, we look at music perception and build a non-corporeal instrument: a fully air-coupled finite-element-modeled Titian Stradivarius violin employing CT-scan reconstruction. The non-corporeal instrument is trained to play the first two measures of the Sonata No. 1 in G-minor, BWV 1001: II. Fuga. Allegro by Bach, using a constrained optimization approach. The musical piece played is found to be indistinguishable from Itzhak Perlman’s concert performance used to train the instrument. The non-corporeal violin allows us to study two new ways in which design changes may be perceived. Firstly we implement design modifications important to violin acoustics and show corresponding plucked and bowed string sounds. Secondly we look at how a violinist would compensate for these design modifications by altering their input actions to obtain the desired sound. The former is advantageous to violin makers who can experiment with changes without making them on their physical instrument. The latter provides a playability metric to classify violins similar to how a player might perceive them. In addition to perception of violin sounds, we show acoustic features of a violin such as its efficiency as a measure of power entering the instrument to the power radiated as sound. This is found to vary from roughly 15\% in the male Baritone voice range to 25\% in the female Mezzo-Soprano and Soprano voice range before falling off to 15\% beyond. The consequences of these efficiency variations on player compensations for uniform sound across musical notes is shown. Additionally, we show the parts of a violin contributing to radiated sound: f-holes dominate radiation at the low frequencies near the Helmholtz resonance transitioning to a predominantly body-induced radiation at higher frequencies through the top plate. The non-corporeal violin also allows us to “see” the sound through a complete spatial characterization of acoustic pressures from the surface of the violin out to the far-field in three-dimensional space. The accuracy of our results are shown by validating against experimentally measured structural velocities in the entire spectral range of importance to violin radiation. Experimental matching so obtained is primarily a consequence of the air-coupling together with the implementation of instrument quality wood as an orthotropic viscoelastic material to capture elasticity and damping properties. The high impedance contrast approaches developed here can be applied to related acoustic problems involving geophysical, biological and naval structures in air, water and other fluid media. Ph.D. 2024-01-16T21:52:23Z 2024-01-16T21:52:23Z 2023-06 2023-07-19T18:41:54.283Z Thesis https://hdl.handle.net/1721.1/153340 0009-0006-8734-8828 In Copyright - Educational Use Permitted Copyright retained by author(s) https://rightsstatements.org/page/InC-EDU/1.0/ application/pdf Massachusetts Institute of Technology |
| spellingShingle | Krishnadas, Arun Optimality of human acoustic perception of natural sounds, and violin acoustics elucidated with a non-corporeal musical instrument made by fully air-coupled finite-element-modeling of the Titian Stradivarius |
| title | Optimality of human acoustic perception of natural sounds, and violin acoustics elucidated with a non-corporeal musical instrument made by fully air-coupled finite-element-modeling of the Titian Stradivarius |
| title_full | Optimality of human acoustic perception of natural sounds, and violin acoustics elucidated with a non-corporeal musical instrument made by fully air-coupled finite-element-modeling of the Titian Stradivarius |
| title_fullStr | Optimality of human acoustic perception of natural sounds, and violin acoustics elucidated with a non-corporeal musical instrument made by fully air-coupled finite-element-modeling of the Titian Stradivarius |
| title_full_unstemmed | Optimality of human acoustic perception of natural sounds, and violin acoustics elucidated with a non-corporeal musical instrument made by fully air-coupled finite-element-modeling of the Titian Stradivarius |
| title_short | Optimality of human acoustic perception of natural sounds, and violin acoustics elucidated with a non-corporeal musical instrument made by fully air-coupled finite-element-modeling of the Titian Stradivarius |
| title_sort | optimality of human acoustic perception of natural sounds and violin acoustics elucidated with a non corporeal musical instrument made by fully air coupled finite element modeling of the titian stradivarius |
| url | https://hdl.handle.net/1721.1/153340 |
| work_keys_str_mv | AT krishnadasarun optimalityofhumanacousticperceptionofnaturalsoundsandviolinacousticselucidatedwithanoncorporealmusicalinstrumentmadebyfullyaircoupledfiniteelementmodelingofthetitianstradivarius |