Robert Gaspar

The evaluation of speech intelligibility in a simulated driving environment using the hearing in noise test

The implementation of the hearing in noise test (HINT) was carried out using an NVH driving simulator in order to evaluate the speech intelligibility in a car between driver and passenger for a variety of driving speeds and the configurations of the talker and of the listener. The sentence reception threshold (sSRT) was determined for each of the various communication situations. When presented with the same listening task, the participants required on average an approximate 3 dB increase in sound pressure level of the HINT speech material while driving and listening compared to when just listening, for an equivalent speech intelligibility performance. A suggested improvement to the current state of art would be to develop a driving simulation for acoustic perception jury testing as described in this study. This would form the basis of a standard method for a more complete, accurate and repeatable evaluation of in-vehicle speech intelligibility.

An experimental and finite element investigation into the energy absorption characteristics of a steering wheel armature in an impact

Abstract Understanding the energy absorption characteristics of automotive components is necessary for the development of safe and crashworthy vehicles. This research experimentally and numerically studies the energy absorption performance of a steering wheel armature in contact with a deformable chestform (bodyform) during a collision. Variations in the location of impact on the armature, armature orientation, and chestform impact velocity are considered to investigate how these factors affect the energy absorption characteristics of the two contacting entities. By implementing standardized testing procedures (under experimental and numerical testing methods) steering wheel armature design can be evaluated and improved on in the design stage of steering wheels. Comparisons between experimental and finite element analysis testing methods were conducted and correlated using load versus displacement profiles over the duration of impact. A good relationship between the two methods was found which allows for investigation into the energy analysis of the armature and the chestform. Experimental methods do not provide a method of determining the energy absorbed by any single entity in this “deformable to deformable” contact. The energy absorbed by both structures can be experimentally determined, however, this does not provide engineers and steering wheel designers with specific information regarding the safe design of just the steering wheel armature. Numerical simulations do provide a means of quantifying the energy absorbed by specific structures in the analysis and do significantly help in isolating the energy absorption characteristics of the steering wheel armature. The results of this research show that the steering wheel armature is responsible for the majority of energy absorbed by the impact. In addition, the percentage of energy absorbed by the armature is not significantly dependent upon the location of impact and the impact velocity.

Development and analysis of a prototype car-carrier structure using the finite element method.

This paper describes a computer-based modeling and simulation effort to aid in the development and design improvements of a prototype car-carrier structure. The most common approach for transporting vehicles over land in North America is the use of truck auto-carriers. The auto-carriers structures and weld points often crack and break during service due to fatigue stresses. In addition, the large deflections on the top decks of the auto-carrier contribute considerable damage to the carrier structures and to the loaded vehicles. In this research, a finite element model of a prototype car-carrier structure was developed and numerical computations were conducted in LS-DYNA. The simulation results correlated well with responses observed from actual car-carriers. Stress distribution and deflections of the structures were investigated when the trailer negotiates speed bumps. Structural modifications were considered to minimize deflections and stress concentrations.

A-weighting the equal loudness contours

The standardized equal loudness contours identify the non-linearities of the human auditory system using simple sinusoidal input signals. The graphical illustration of auditory performance trends provides a visual representation of these non-linearities with respect to both frequency and amplitude across the range of auditory perception. Metrics such as the A-Weighting filter approximate one generalized curve shape, in an effort to quantify measured values in a manner that represents the perception of the measured sound. With the release of the ISO226:2003 version of the standard, the most recent version of the equal loudness contours provide an improved contour set with more refined shapes and steeper slopes. The purpose of this study is to investigate the performance of the A-weighting function compared to the updated curves of the equal loudness contours. Included is an examination and discussion of the appropriateness of the continued use of the existing A-Weighting filter. Given the overall un-hyperb...

Proposed hybrid multiple look approach for calculating unsteady loudness

Experimental studies have shown that for short gaps between 2 to 5 ms, the perceived loudness is higher than for uninterrupted noise presented to the ear. Other studies have also shown that the present temporal integration models for the calculation of time varying loudness do not adequately account for short duration phenomena. It has been proposed that the multiple look approach is a more applicable method for describing these short term circumstances. This approach breaks a sound into very small durations which allows for the intelligent processing of the looks and decision making depending on the nature of the stimulus. However, present technologies, such as the Fast Fourier Transform, are not adequate to deal with short duration sounds across the entire frequency spectra. A compromised approach using a proposed hybrid model is presented to account for perceived loudness levels for sounds in the presence of gaps while using an integration model. This hybrid multiple look model was tested using several...

Use of Psychoacoustic Metrics for the Analysis of Next Generation Computer Graphic Card Noise

The continuing challenge to deliver performance improvements in computer graphic cards has long since progressed to the point of requiring finned, passive, cooling devices to dissipate the heat generated by the graphics processing unit (GPU). The heat flux generated by further improvements now exceeds that dissipation capacity so that passive cooling can no longer provide adequate cooling the GPU. The dissipation rates required by the latest generation of designs can be delivered by forced air cooling of finned heat sinks. The concurrent challenge to the industry is to provide this cooling while minimizing the noise generated by these cooling fans. A significant aspect associate with this problem is missed if one only considers the problem to be a one-dimensional sound level issue. From a consumer’s perspective, the perceived quality of the noise emitted takes precedence over what traditional acoustical analysis techniques of this fan noise may imply. Here, psychoacoustic or sound quality metrics, may be a more applicable analysis tool as it provides the quantification of these qualitative human impressions. The present study investigates the validity of using several psychoacoustic metrics for the analysis of fan cooled computer graphics card noise. Using experimentally measured fan noise from three different cooling fan designs, a sound quality analysis was performed using loudness, sharpness, roughness, fluctuation strength, prominent tone and articulation index. A discussion and comparison of measured results using traditional analysis techniques is also included. It was found that some of the metrics proved more useful than others as an analysis tool for this specific noise source. A discussion of the applicability of the various sound quality metrics along with justifications is presented.Copyright

Experimental and numerical testing of a prototype car-carrier structure with suggested design improvements

This paper describes a computer-based modelling, simulation, and validation effort to aid in the development, testing, and design improvement of a prototype car-carrier structure. In this research, a finite-element model of a prototype car-carrier structure was developed and numerical computations were conducted using LS-DYNA to investigate the stress/strain distribution within the carrier structure when negotiating a typical speed bump. The model was compared with experimental results taken from tests using a truck car-carrier of similar configuration to the trailer investigated in this research. Local and global geometric modifications were made to minimise lateral structural deflections and stress and strain concentrations.

THE EFFECT OF IMPACT VELOCITY AND STEERING WHEEL ORIENTATION ON THE CRASHWORTHINESS OF A STEERING WHEEL ARMATURE

Abstract Experimental testing which examines the effects of variations in the column angle and wheel angle of the steering wheel and the velocity at which a chestform impacts the steering wheel armature is the focus of this research. The capability of predicting loads and absorbed energy in any impact between the driver of a vehicle and the steering wheel is very significant in steering wheel design and occupant safety. Methods of illustrating the effects of the wheel angle and column angle (for a prescribed impact velocity) on peak impact load, peak displacement, and energy absorption are presented in this paper. It was observed that experimental observations (impact load, displacement, and energy absorption) are very dependent upon the orientation of the steering wheel armature and chestform velocity when impact occurs between the two entities.