The Evolution and Design of Flat-Panel Loudspeakers for Audio Reproduction

The underlying physics and the design of loudspeakers that radiate sound through the bending vibrations of elastic panels, here referred to generically as flat-panel loudspeakers, are reviewed in this paper. The form factor, reduced weight, and aesthetic appeal of flat-panel speakers have made them a topic of interest for more than 90 years, but these advantages have been overshadowed by acoustical shortcomings, specifically the uneven frequency response and directivity in comparison to conventional cone-radiator loudspeakers. Fundamentally, the design challenges of flat-panel speakers arise from the intrinsically large number of mechanical degrees of freedom of a panel radiator. A number of methods have been explored to compensate for the acoustical shortcomings of flat-panel speakers, such as employing inverse filters, equalization, canceling mechanical resonances with actuator arrays, and modifying the panel material, shape, structure, and boundary conditions. Such methods have been used in various combinations to achieve significant audio performance improvements, and carefully designed flat-panel loudspeakers have been rated in blind listening tests as competitive with some prosumer-grade conventional loudspeakers. This review presents a brief historical account of the evolution of flat-panel loudspeakers and summarizes the essential physics and design methodologies that have been developed to optimize their fidelity and directional response.

[1]  Mark F. Bocko,et al.  Evaluating Listener Preference of Flat-Panel Loudspeakers , 2019 .

[2]  B. B. Bauer,et al.  Fundamentals of acoustics , 1963 .

[3]  Hareo Hamada,et al.  A MULTIPLE MICROPHONE RECORDING TECHNIQUE FOR THE GENERATION OF VIRTUAL ACOUSTIC IMAGES , 1999 .

[4]  Manfred R. Schroeder,et al.  Statistical parameters of the frequency response curves of large rooms , 1987 .

[5]  Floyd E. Toole Subjective Measurements of Loudspeaker Sound Quality , 1982 .

[6]  Kuonan Li A critical review of bending wave loudspeaker technology and implementation , 2010 .

[7]  Marinus M. Boone Multi-Actuator Panels (MAPs) as Loudspeaker Arrays for Wave Field Synthesis , 2004 .

[8]  Basilio Pueo,et al.  Efficient equalization of multi-exciter distributed mode loudspeakers , 2009 .

[9]  Jose J. Lopez,et al.  Multiactuator Panels for Wave Field Synthesis: Evolution and Present Developments , 2011 .

[10]  F. H. Brittain Loudspeakers: relations between subjective and objective tests , 1953 .

[11]  Mark F. Bocko,et al.  Optimized Driver Placement for Array-Driven Flat-Panel Loudspeakers , 2017 .

[12]  David Thompson,et al.  Sound radiation from rectangular baffled and unbaffled plates , 2010 .

[13]  C. Fuller,et al.  Piezoelectric Actuators for Distributed Vibration Excitation of Thin Plates , 1991 .

[14]  Sangbum Park,et al.  A Study on the Characteristics of Electroencephalography (EEG) by Listening Location of OLED Flat TV Speaker , 2018, CSII.

[15]  Neil Harris Modelling Acoustic Room Interaction for Pistonic and Distributed-Mode Loudspeakers in the Correlation Domain , 2004 .

[16]  Jeong-Guon Ih,et al.  Vibration rendering on a thin plate with actuator array at the periphery , 2015 .

[17]  Diemer de Vries,et al.  Wave Field Synthesis using Multi-Actuator Panel: Further Steps to Optimal Performance , 2006 .

[18]  D.R.罗伯茨 An acoustic device , 2014 .

[19]  Sebastian Merchel,et al.  Low Deviation and High Sensitivity—Optimized Exciter Positioning for Flat Panel Loudspeakers by Considering Averaged Sound Pressure Equalization , 2019 .

[20]  Mark F. Bocko,et al.  Flat-Panel Loudspeaker Simulation Model with Electromagnetic Inertial Exciters and Enclosures , 2017 .

[21]  Xiaodong Li,et al.  Vibrational Contrast Control for Local Sound Source Rendering on Flat Panel Loudspeakers , 2018 .

[22]  Mark F. Bocko,et al.  Near-Field Object-Based Audio Rendering on Flat-Panel Displays , 2019 .

[23]  Colin H. Hansen,et al.  Active control of vibration , 1996 .

[25]  Neville Thiele,et al.  Loudspeakers in Vented Boxes: Part 1 , 1971 .

[26]  Nassim BENBARA,et al.  Bending waves focusing in arbitrary shaped plate-like structures: Application to spatial audio in cars , 2020 .

[27]  Yong Shen,et al.  Positions Effect of Multi Exciters and the Optimization on Sound Pressure Responses of Distributed Mode Loudspeaker , 2006 .

[28]  Graham Bank The Intrinsic Scalability of the Distributed Mode Loudspeaker (DML) , 1998 .

[29]  Floyd E. Toole Loudspeaker Measurements and Their Relationship to Listener Preferences: Part 1 , 1986 .

[30]  이우종,et al.  A display apparatus , 2012 .

[31]  Sheila Flanagan,et al.  Loudness: A Study of the Subjective Difference between DML and Conventional Loudspeaker , 1999 .

[32]  Sean Olive A Multiple Regression Model for Predicting Loudspeaker Preference Using Objective Measurements: Part I - Listening Test Results , 2004 .

[33]  Robert L. Clark,et al.  Piezoelectric Actuators for Distributed Vibration Excitation of Thin Plates: A Comparison Between Theory and Experiment , 1993 .

[34]  F. Fahy,et al.  Sound and Structural Vibration: Radiation, Transmission and Response , 1987 .

[35]  Sandra Brix,et al.  Structural and Acoustic Analysis of Multiactuator Panels , 2006 .

[36]  Etienne Corteel,et al.  Multichannel Inverse Filtering of Multiexciter Distributed Mode Loudspeakers for Wave Field Synthesis , 2002 .

[37]  Sheila Flanagan,et al.  Investigation Into the Relationship Between Subjective Loudness and Auditory Distance Perception , 1999 .

[38]  郭仁炜,et al.  A display device , 2013 .

[39]  James A. S. Angus Distributed Mode Loudspeaker Polar Patterns , 1999 .

[40]  Mark F. Bocko,et al.  A Model for the Impulse Response of Distributed-Mode Loudspeakers and Multi-Actuator Panels , 2015 .

[41]  C. Fuller,et al.  Experiments on active control of structurally radiated sound using multiple piezoceramic actuators , 1990 .

[42]  Kirill V. Horoshenkov,et al.  Intensity Measurements of the Acoustic Emission from a DML Panel , 2002 .

[43]  A. P. Berkhoff,et al.  Flat acoustic sources with frequency response correction based on feedback and feed-forward distributed control. , 2015, The Journal of the Acoustical Society of America.

[44]  Jakob S. Jensen,et al.  Spectrally smooth and spatially uniform sound radiation from a thin plate structure using band gaps , 2020 .

[45]  Mark F. Bocko,et al.  Source rendering on dynamic audio displays , 2017, 2017 IEEE Workshop on Applications of Signal Processing to Audio and Acoustics (WASPAA).

[46]  A. Berkhout,et al.  Acoustic control by wave field synthesis , 1993 .

[47]  Vladimir Gontcharov,et al.  Diffusivity Properties of Distributed Mode Loudspeakers , 2000 .

[48]  Mark F. Bocko,et al.  Modal Crossover Networks for Flat-Panel Loudspeakers , 2016 .

[49]  Jörg Panzer,et al.  Distributed-Mode Loudspeaker Simulation Model , 1998 .

[50]  Kwanho Park,et al.  16‐3: Study on Enhancement of the Sound Quality by Improvement of Panel Vibration in OLED TV , 2018 .

[51]  J L Thomas,et al.  Time reversal and the inverse filter. , 2000, The Journal of the Acoustical Society of America.

[52]  Malcolm J. Hawksford,et al.  Stereophonic Localization in the Presence of Boundary Reflections, Comparing Specular and Diffuse Acoustic Radiators , 1998 .

[53]  Floyd E. Toole Subjective Measurements of Loudspeaker Sound Quality and Listener Performance , 1985 .

[54]  Etienne Corteel,et al.  From vibration to perception: using Large Multi-Actuator Panels (LaMAPs) to create coherent audio-visual environments , 2012 .

[55]  Mark F. Bocko,et al.  Equalization of Localized Sources on Flat-Panel Audio Displays , 2017 .

[56]  R. L. Eisenberg Diaphragm , 2019, What Radiology Residents Need to Know: Chest Radiology.

[57]  Suzhen Zhang,et al.  Model Optimization of Distributed-Mode Loudspeaker Using Attached Masses , 2006 .

[58]  Mark F. Bocko,et al.  Measures of vibrational localization on point-driven flat-panel loudspeakers , 2016 .

[59]  Chris R. Fuller,et al.  Active control of noise transmission through rectangular plates using multiple piezoelectric or point force actuators , 1991 .

[60]  Jose J. Lopez,et al.  Strategies for bass enhancement in Multiactuator Panels for Wave Field Synthesis , 2010 .

[61]  Basilio Pueo,et al.  A note on the filtering equalization in large multiactuator panels , 2009, 2009 17th European Signal Processing Conference.

[62]  Yong Shen,et al.  Modal Optimization of Distributed Mode Loudspeaker , 2005 .

[63]  M. Fink,et al.  Time reversal of ultrasonic fields. I. Basic principles , 1992, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.

[64]  Graham Bank,et al.  The Distributed Mode Loudspeaker-Theory and Practice , 1998 .

[65]  Malcolm J. Hawksford MATLAB Program for Loudspeaker Equalization and Crossover Design , 1999 .

[66]  Mark F. Bocko,et al.  Sound-Source Localization On Flat-Panel Loudspeakers , 2017 .

[67]  Leonard Meirovitch,et al.  Modal control of traveling waves in flexible structures , 1986 .

[68]  Scott D. Snyder,et al.  Active control of sound radiation from a vibrating rectangular panel by sound sources and vibration inputs: An experimental comparison , 1991 .

[69]  L. Cremer,et al.  Structure-Borne Sound: Structural Vibrations and Sound Radiation at Audio Frequencies , 1973 .

[70]  Jordan Cheer,et al.  A system for controlling the directivity of sound radiated from a structure. , 2020, The Journal of the Acoustical Society of America.