Loudspeaker System Research Articles

Architectural impacts on speech intelligibility in atrium spaces: Two case studies.

Case study reviewing the speech transmission index and voice intelligibility design and implementation of two atrium spaces where dedicated public address systems were implemented. The architectural design and selection of finishes has a great impact on the capability of any public address loudspeaker system distinct from any system performance characteristics. The presentation will review the design process, acoustical modeling, and testing results outlining the issues associated with meeting the NFPA 72 Common Intelligibility Score suggested goals. Architectural design requirements such as day-lighting and views are increasing large areas of glass in atrium spaces. These designs are making intelligibility increasingly difficult and the electronic systems and loudspeaker designs can only accomplish so much without architectural acoustical finishes as part of the design.

Integrated loudspeaker system

The invention relates to a loudspeaker system comprising several sonic converters (2) which are fixed in or to the rear of sound passage openings (3) in a carrier plate. The loudspeaker system is characterized in that the carrier plate is embodied in the form of a wall plate (1) for the interiors or outer facades of buildings and in that the sonic converters (2) are integrated into the carrier plate. The inventive loudspeaker system makes it possible to acoustically irradiate an area without the need for esthetically troublesome loudspeakers.

Light bulb loudspeaker and sound system

A light bulb loudspeaker and sound system where a wireless or wire receiver, amplifier and power supply can be mounted inside of the boundary defined by a light bulb and base where the glass bulb can be used as a sound radiating diaphragm, or alternatively, the bulb can be made to move as a plunger and this act as a sound diaphragm. A transducer can convert audio from the amplifier into sound and thereby excite the glass bulb or cause it to move. A baffle can optionally be provided in the form of a lamp shade or otherwise. Different channels can provide different audio signals to different light bulb loudspeakers in the same physical area, or an electrical signal could be multiplexed. A small base station unit can transmit radio or wire signals containing audio information from an audio source such as a stereo. The filament can optionally be used as a radio receiving antenna.

Optimizing the Directivity of Multiway Loudspeaker Systems

In multiway loudspeaker systems, digital signal processing techniques have been used to correct the frequency response, the propagation time, and the lobbing errors. These solutions are mainly based on correcting the delays between the signals coming from loudspeaker system transducers, and they still show limited performances over the overlap frequency bands. In this paper, we propose an enhanced optimization of relevant directivity characteristics of a multiway loudspeaker system such as the frequency response, the radiation pattern, and the directivity index over an extended transducers' frequency overlap bands. The optimization process is based on applying complex weights to the crossover filter transfer functions by using an iterative approach.

Loudspeaker system providing improved sound presence and frequency response in mid and high frequency ranges

A speaker system includes a first, second and third sound radiators with the second sound radiator positioned medially between the first and third sound radiators. The radiators project first, second and third sound vectors respectively, with the second sound vector oriented vertically and the first and third sound vectors directed generally toward each other at angles above the horizontal so as to intersect at an inclusive angle between 90 and 170 degrees. Sound from the first and third radiators impinges on the second radiator so as to cause an echo effect improving sound spaciousness. The first and third radiators are placed at different angles relative to the listener and at different heights as well to improve time delays in the two radiated signals.

Curved line array loudspeaker

A loudspeaker system consisting of a plurality of direct-radiating electro- acoustical drivers arrayed along a curved line. While in one embodiment the curved line array may be a spiral array, in another embodiment it may be any curved line array (such as an arcuate array). The acoustical drivers are directly coupled to an acoustical waveguide without use of adapters or a throat section. The waveguide and the acoustical drivers may thus be oriented along the curved line so as to produce controlled vertical and horizontal angular coverage with improved phase coherence and reduced distortion. A plurality of phase plugs may be interspersed between the plurality of acoustical drivers to assist in equalizing the sound path to achieve uniform phase at the mouth of the waveguide.

Spiral line array loudspeaker

A loudspeaker system consisting of a plurality of direct-radiating electro-acoustical drivers arrayed along a spiral line. The acoustical drivers may be directly coupled to an acoustical waveguide without use of adapters or a throat section. The waveguide and the acoustical drivers may thus be oriented along the spiral line so as to produce controlled vertical and horizontal angular coverage with improved phase coherence and reduced distortion. A plurality of phase plugs may be interspersed between the plurality of acoustical drivers to assist in equalizing the sound path to achieve uniform phase at the mouth of the waveguide.

Evaluating the practical performance and benefits of various loudspeaker styles for party wall and floor/ceiling assembly field sound transmission testing.

The instrumentation and equipment used in field sound transmission testing of multi-family residence party walls and floor ceiling assemblies have steadily improved. ASTM E336 suggests the use of omnidirectional speakers for such performance tests. When directional box speakers are used, they need to be placed in and face toward a corner of the sound source room. Since many multi-family residential complexes are two stories and higher, the need to move heavy equipment (including massive speakers) from room to room and floor to floor can be a challenge. It is therefore desirable to optimize weight and performance. This paper compares the functionality and performance of the standard directional box-type loudspeaker (90 dB at 1 m, 350-W maximum input, 90 lbs), an omnidirectional dodecahedron spherical loudspeaker (110 dB at 1 m, 480-W maximum input, 30 lbs) and a prototype omnidirectional dodecahedron spherical loudspeaker (120 dB at 1 m, 1000-W maximum input, 35 lbs). In addition to comparing the acoustical output of these different loudspeaker systems, their tendency to introduce vibrations into the source room floor is also discussed.

Feasibility of testing three salivary stress biomarkers in relation to naturalistic traffic noise exposure

Stress dependent alterations of the salivary biomarkers alpha-amylase (sAA), salivary chromogranin A (sCgA) and salivary cortisol (sC) have been reported in numerous studies recently. The aim of this pilot study was to investigate the feasibility of testing sAA, sCgA and sC in relation to naturalistic traffic noise exposure in order to monitor a direct stress response in a laboratory setup. A total of twenty study participants were exposed to binaurally recorded naturalistic traffic noise samples containing 75 dB (L(A,)eq) for 20 minutes via a loudspeaker system. Saliva was collected directly before and after defined exposure to naturalistic traffic noise. Determination of sAA was performed enzymatically on a Hitachi 912 laboratory analyzer, sCgA was determined by ELISA technique and sC was determined using a RIA assay. There was a significant increase of sAA and sC concentrations after traffic noise exposure (p=0.045; p=0.01), whereas for sCgA this was not observed (p=0.48). Measuring of sAA and sC appear to be feasible to investigate direct stress effects in relation to naturalistic traffic noise exposure in a laboratory setup. Considering the small sample size of this pilot study, these observations need to be further proved in a larger explorative study.

A Pedagogical Software for the Analysis of Loudspeaker Systems

In this paper, a pedagogical software for the design and analysis of loudspeaker systems is presented, with emphasis on training students in the interaction between system parameters. Loudspeakers are complex electromechanical system, whose behavior is neither intuitive nor easy to understand by inexperienced students. Although commercial simulation software provides computation of the equations governing loudspeaker systems, they are mainly focused on the final product and are intended for experienced audio engineers. The proposed software was intentionally designed for education and training purposes. This software allows students to investigate loudspeaker systems that involve complex interactions by illustrating their effects in real time, both in a graphical interface and in numeric values. Unlike other academic simulation tools in the technical literature, students can modify the system parameters, both graphically and numerically, and observe their impact on the loudspeaker responses: pressure, diaphragm behavior, and electrical impedance. Results obtained during two academic semesters showed educational improvement by comparing the outcomes generated by a commercial software and by the designed tool. Students reported very positive attitudes toward this experience and perceived their interaction with the simulation as being generally effective in improving their skills in dealing with loudspeaker system interaction.

Real-time rowing simulator with multimodal feedback

Efficient rowing requires both physical and technical abilities of the human. Teaching and learning of the technical abilities is thereby mainly restricted to on-water training. The aim of this project was to develop a rowing simulator. This simulator should serve as a high-level indoor training tool that can be used by rowing novices and professionals. The users should perceive acoustic, visual, and haptic cues about their current performance and their environment in real time. The newly-developed rowing simulator consists of a rowing boat hull equipped with multiple position sensors attached to the oar and seat. The boat hull was mounted on a podium placed inside a Cave setup. The Cave comprises projection screens, a loudspeaker system, and actuated winches for visual, acoustic, and haptic feedback, respectively. A mathematical real-time rowing model was developed, which computes the boat velocity and the oar force as a function of the movement of the oar and the user. All relevant boat, oar, and user parameters can be arbitrarily set, thus allowing the simulation of different boat types. The rowing model was validated by comparing results of the simulation with data from on-water measurements. Both the boat velocity and the oar force predicted by the model correlated highly with the experimentally-obtained data. Furthermore, the rowing simulator was successfully tested with professional rowers who rated the level of realism and the applicability of the simulator for indoor training as high. Based on the feedback of the rowers, various hardware and software extensions are planned for the simulator, including an increase of the number of actuated degrees of freedom of the boat and the oar, in order to improve the haptic feedback. © 2008 John Wiley and Sons Asia Pte Ltd

A micro-machined source transducer for a parametric array in air

Parametric array applications in air, such as highly directional parametric loudspeaker systems, usually rely on large radiators to generate the high-intensity primary beams required for nonlinear interactions. However, a conventional transducer, as a primary wave projector, requires a great deal of electrical power because its electroacoustic efficiency is very low due to the large characteristic mechanical impedance in air. The feasibility of a micro-machined ultrasonic transducer as an efficient finite-amplitude wave projector was studied. A piezoelectric micro-machined ultrasonic transducer array consisting of lead zirconate titanate uni-morph elements was designed and fabricated for this purpose. Theoretical and experimental evaluations showed that a micro-machined ultrasonic transducer array can be used as an efficient source transducer for a parametric array in air. The beam patterns and propagation curves of the difference frequency wave and the primary wave generated by the micro-machined ultrasonic transducer array were measured. Although the theoretical results were based on ideal parametric array models, the theoretical data explained the experimental results reasonably well. These experiments demonstrated the potential of micro-machined primary wave projector.

Narrow opening electroacoustical transducing

A loudspeaker system having an enclosure having a narrow opening or slot for radiating high frequency acoustic energy. The loudspeaker system has a cover member defining a slot between the cover member and a boundary of a listening space. The loudspeaker system may also include a fixed or adaptive equalizer for modifying frequency response anomalies resulting from the interaction of the acoustic energy, the narrow opening, and the boundary.

On the radiation and wave propagation of sound within horns.

The horns used in loudspeaker systems are well known for their ability to increase radiation efficiency and control directivity. Because of the horn’s ubiquitous nature, significant research efforts have been undertaken to explore both its directional and frequency response characteristics. The following research reported in this presentation incorporates several numerical methods (including finite difference and boundary element analysis) to better understand the nature of wave propagation through horns and the effects that geometrical and configurational changes have in better controlling directivity and improving frequency response.

Comparison of consonant identification improvements by steady-state suppression via a loudspeaker system between with and without natural sounds from a talker in reverberation

Comparison of consonant identification improvements by steady-state suppression via a loudspeaker system between with and without natural sounds from a talker in reverberation

Low frequency surface array

A low-frequency loudspeaker system based on a dipole principle. In some implementations, the system includes an open frame rigging system and multiple subwoofers mounted in a dipole surface array configuration in the open frame rigging system to produce controlled sound dispersion in both horizontal and vertical planes. The subwoofers are operable to produce low-frequency sound dispersion below about 300 Hz. The subwoofers mounted in the dipole configuration include a first set of subwoofers facing a first direction and a second set of subwoofers facing a second direction, in which the second direction is facing a direction that is 180 degrees with respect to the first direction. The second set of subwoofers are wired out-of-phase with respect to the first set of subwoofers to reduce non-liner distortion. The first and second sets of subwoofers are configured to concurrently move in a same direction when a signal is applied to the subwoofers.

Loudspeaker and components for use in construction thereof

A loudspeaker and components for use in the construction thereof is provided. In one aspect, the present invention relates generally to a new type of loudspeaker comprising a driver having a sound radiating element, at least two motor elements which, in operation, cooperate to move the sound radiating element in response to an applied signal, and mounting elements coupled to the sound radiating element and motor elements, where the first motor element is mechanically coupled to the sound radiating element, and where the driver comprises at least two mechanical masses which, in operation, move independently in response to the applied signal. The mechanical masses are mechanically coupled such that in operation, the driver has at least fourth order frequency characteristics. This facilitates, for example, the construction of a fourth order loudspeaker system that performs like a vented enclosure system without employing a vent. Associated loudspeaker components and design processes employable in other loudspeaker constructions are also disclosed.

An Estimation Method of Parameters for Closed-box Loudspeaker System

In this paper, we propose a method that uses Simulated Annealing (SA) to estimate the linear and nonlinear parameters of a closed-box loudspeaker system for implementing effective Mirror filters. The nonlinear parameters determined by W. Klippel's method are sometimes inaccurate and imaginary. In contrast, the proposed method can estimate the parameters with satisfactory accuracy due to its use of SA; the resulting impedance and displacement characteristics match those of an actual equivalent loudspeaker. A Mirror filter designed around these parameters can well compensate the nonlinear distortions of the loudspeaker system. Experiments demonstrate that the method can reduce the levels of nonlinear distortion by 5 dB to 20 dB compared to the before compensation condition.

The engineering method of sound field control for amplifications in sports arena

This paper discusses the engineering method of sound field control for amplifications in sports arena, which includes the selection, assembly and adjustment of the loudspeaker system. It also includes the site characteristics of the sports arena, as well as the relations between the loudspeaker and the site. Through the measurements of the rated sensitivity and maximum noise power, the loudspeaker system can be determined as distributed or central system, linear or plane array. With the adjustments on parameters such as the directivity D(Θ)and the directivity factor Q, the loudspeaker system will be able to effectively control the sound field during amplification process and to achieve better sound quality in sports arena. Besides determining the effective engineering method for sound field control in the amplification process, this paper also considers the acoustical characteristics of sound sources and coupling effect in the sound field.

A comparison between two methods for speech transmission quality assessment with noise simulation at receiver's side

Two auditory experiments are presented that were designed in order to compare two different methods for the assessment of speech quality when noise at listener's side is present: (1) Headphone presentation with samples pre‐recorded over a head and torso simulator, and (2) test participants located in a noisy environment, rendered by a 4.1 loudspeaker system. Real‐world types of background noise were employed as well as a variety of user terminals. The correlation between corresponding overall quality scores amounts to r = 0.9. Hence, a headphone presentation can replace a loudspeaker noise simulation in principle, leading to the consequence that a simpler experimental set‐up is sufficient for assessing the speech quality when noise is present at the receiver's side. However, there exist certain differences between both quality scores. For example, in most cases clean wideband (50‐7000 Hz) and standard narrow‐band (300‐3400 Hz) speech are rated slightly lower if the samples are presented over a headphone a...