Improved Directivity of Flat Panel Loudspeakers by Minimizing the Off-Axis Radiation below Coincidence

Benjamin Zenker; Robert Schurmann; Sebastian Merchel; Ercan Mehmet Altinsoy

doi:10.3390/app11157001

Improved Directivity of Flat Panel Loudspeakers by Minimizing the Off-Axis Radiation below Coincidence

Applied Sciences ◽

10.3390/app11157001 ◽

2021 ◽

Vol 11 (15) ◽

pp. 7001

Author(s):

Benjamin Zenker ◽

Robert Schurmann ◽

Sebastian Merchel ◽

Ercan Mehmet Altinsoy

Keyword(s):

Numerical Methods ◽

Pressure Level ◽

Flat Panel ◽

Promising Alternative ◽

Directivity Factor

Flat panel loudspeakers are a promising alternative to conventional loudspeakers. In particular, quasi-omnidirectional radiation at higher frequencies is stressed as an advantage of these systems compared to conventional speaker systems. However, this advantage can also be considered a disadvantage. Compared to that from conventional speakers with a flat and smooth on-axis and off-axis response, this wide radiation from flat panel loudspeakers occurs with an inconstant directivity factor, which can cause coloration and unusual spatial artifacts. This paper investigated the root causes of inhomogeneous directivity by using numerical methods. Based on these analyses, specific prototypes with various damping layups were built to overcome this problem. The additional damping layer reduces the off-axis radiation without significantly reducing the pressure level in the listening window. This approach is simple, robust, inexpensive and effective for improving the directivity of flat panel loudspeakers.

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A NEW NUMERICAL APPROACH FOR FIRE SIMULATION

International Journal of Modern Physics C ◽

10.1142/s0129183107010462 ◽

2007 ◽

Vol 18 (02) ◽

pp. 187-202 ◽

Cited By ~ 17

Author(s):

SHENG CHEN ◽

ZHAOHUI LIU ◽

ZHU HE ◽

CHAO ZHANG ◽

ZHIWEI TIAN ◽

...

Keyword(s):

Numerical Methods ◽

Numerical Approach ◽

Fire Research ◽

Fire Simulation ◽

Promising Alternative ◽

Urgent Task ◽

Combustion Simulation ◽

Order Of Magnitude ◽

Complicated Geometries ◽

In Fire

It is an urgent task to adopt/develop new numerical methods in fire research because of the intrinsic disadvantages of traditional numerical methods, such as in complicated geometries treatment, computational efficiency on parallel computers. The outstanding features of the lattice Boltzmann method (LBM) has emerged which is a very promising alternative in this field. Unfortunately, until recently the LBM could not be employed in fire research due to its inherent defects in combustion simulation. In order to extend the LBM into fire research, a novel LB model for fire simulation is designed in this study. Besides the intrinsic advantages of the standard LBM, this model shows improved numerical stability and can cover temperature ratio of more than one order of magnitude. The model is validated through a benchmark test "coflow methane-air diffusion flame". Furthermore, because little attention has been paid to the effect of the interaction between the inlet boundary and the interior of the flow field on stability of the computation and the quality of the solution, therefore in this study we also discuss this problem in detail to bridge this gap.

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Contributions of Voice and Nonverbal Communication to Perceived Masculinity–Femininity for Cisgender and Transgender Communicators

Journal of Speech Language and Hearing Research ◽

10.1044/2019_jslhr-19-00387 ◽

2020 ◽

Vol 63 (4) ◽

pp. 931-947

Author(s):

Teresa L. D. Hardy ◽

Carol A. Boliek ◽

Daniel Aalto ◽

Justin Lewicke ◽

Kristopher Wells ◽

...

Keyword(s):

Fundamental Frequency ◽

Sound Pressure Level ◽

Sound Pressure ◽

Vocal Tract ◽

Presentation Mode ◽

Pressure Level ◽

Presentation Modes ◽

Audiovisual Stimuli ◽

Vocal Tract Resonance ◽

Point Light

Purpose The purpose of this study was twofold: (a) to identify a set of communication-based predictors (including both acoustic and gestural variables) of masculinity–femininity ratings and (b) to explore differences in ratings between audio and audiovisual presentation modes for transgender and cisgender communicators. Method The voices and gestures of a group of cisgender men and women ( n = 10 of each) and transgender women ( n = 20) communicators were recorded while they recounted the story of a cartoon using acoustic and motion capture recording systems. A total of 17 acoustic and gestural variables were measured from these recordings. A group of observers ( n = 20) rated each communicator's masculinity–femininity based on 30- to 45-s samples of the cartoon description presented in three modes: audio, visual, and audio visual. Visual and audiovisual stimuli contained point light displays standardized for size. Ratings were made using a direct magnitude estimation scale without modulus. Communication-based predictors of masculinity–femininity ratings were identified using multiple regression, and analysis of variance was used to determine the effect of presentation mode on perceptual ratings. Results Fundamental frequency, average vowel formant, and sound pressure level were identified as significant predictors of masculinity–femininity ratings for these communicators. Communicators were rated significantly more feminine in the audio than the audiovisual mode and unreliably in the visual-only mode. Conclusions Both study purposes were met. Results support continued emphasis on fundamental frequency and vocal tract resonance in voice and communication modification training with transgender individuals and provide evidence for the potential benefit of modifying sound pressure level, especially when a masculine presentation is desired.

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Influence of the Acoustic Reflex on Vowel Recognition

Journal of Speech Language and Hearing Research ◽

10.1044/jshr.2903.420 ◽

1986 ◽

Vol 29 (3) ◽

pp. 420-424 ◽

Cited By ~ 4

Author(s):

Michael Dorman ◽

Ingrid Cedar ◽

Maureen Hannley ◽

Marjorie Leek ◽

Julie Mapes Lindholm

Keyword(s):

Auditory System ◽

Sound Pressure ◽

Dynamic Range ◽

Recognition Accuracy ◽

Pressure Level ◽

Acoustic Reflex ◽

The Poor ◽

Stapedial Reflex ◽

Vowel Recognition ◽

High Sound

Computer synthesized vowels of 50- and 300-ms duration were presented to normal-hearing listeners at a moderate and high sound pressure level (SPL). Presentation at the high SPL resulted in poor recognition accuracy for vowels of a duration (50 ms) shorter than the latency of the acoustic stapedial reflex. Presentation level had no effect on recognition accuracy for vowels of sufficient duration (300 ms) to elicit the reflex. The poor recognition accuracy for the brief, high intensity vowels was significantly improved when the reflex was preactivated. These results demonstrate the importance of the acoustic reflex in extending the dynamic range of the auditory system for speech recognition.

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