Objective Measurement Techniques Research Articles

Gas-phase analysis of trimethylamine, propionic and butyric acids, and sulfur compounds using solid-phase microextraction.

Complaints due to odors are an important problem for the wastewater, composting, and animal agriculture industries. Accurate, objective measurement techniques are needed to monitor emissions, to develop new waste handling procedures, and to reduce the production of these volatile gases. Solid-phase microextraction was investigated as a technique for the determination of representative odorous gases. A flow-through Teflon chamber was used to expose the fibers to certified gas standards. A 75-microm carboxen-poly(dimethylsiloxane) (Car-PDMS) coating was used for trimethylamine (TMA), carbon disulfide (CS2), dimethylsulfide (DMS), and dimethyl disulfide (DMDS), and an 85-microm polyacrylate coating was used for propionic acid (PA) and butyric acid (BA). Using a 1-h fiber exposure time and a flow rate through the chamber of 72 mL/min, method detection limits were 2.38, 0.074, 0.150, 0.063, 1.85, and 1.32 ppbv for TMA, DMS, CS2, DMDS, PA, and BA, respectively. Enhanced detector signal was observed for all analytes under flow conditions, as compared to static conditions, and the porous nature of the Car-PDMS coating appears to increase the time needed for analytes to reach equilibrium under flow conditions.

Concert hall acoustics—2001

A brief summary is made of major factors encountered in today’s acoustical design of concert halls, including preferred reverberation times, loudness, lateral reflections, seat absorption, suspended panels, need for irregular surfaces to create sound diffusion and eliminate acoustical ‘‘glare,’’ and objective measurement techniques developed from laboratory experiments that can be used to estimate subjective acoustical quality. Objective measurements of these factors have been made in over 70 halls. The results are plotted versus subjective rank-orderings of acoustical quality for these halls. The rank-orderings were obtained from interviews and questionnaires involving conductors, music critics, and music aficionados. The objective quantities plotted are reverberation time, early decay time, spaciousness, lateral fraction, interaural cross-correlation coefficient, initial-time-delay gap, strength factor (sound level), bass ratio, 125-Hz level, and surface diffusivity index.

The effect of target proximity on the aniso-accommodative response

Aniso-accommodation (unequal binocular accommodation) to lens-induced anisometropia has been demonstrated by subjective and objective measurement techniques (Marran and Schor, Vision Res.38(22), 3601–3619). The gain of the response was significantly reduced for some subjects when aniso-accommodation was stimulated by a target at 1m compared to a target at 20cm, even when the targets viewed were matched in retinal image size, convergence levels and aniso-accommodative stimuli. The two conditions did differ in both the accommodative level and proximity of the target. Thus the higher gain of the response in the 20cm condition could have arisen from either high proximity, high accommodative level or a combination of both.In this investigation, target proximity and accommodative level were manipulated independently while extra-retinal cues such as absolute disparity and image size were held constant. The results show that high target proximity alone rather than accommodative level or a combination of the two was responsible for the distance dependent effect demonstrated by subjects. Furthermore, accommodative level did not affect the response when target proximity was held constant. Subjects who demonstrated invariant aniso-accommodation with changes in viewing distance also demonstrated invariant aniso-accommodation with experimental manipulation of target proximity at the target distances tested, as would be expected.These results suggest that high level processing, rather than a reflex blur response, is involved in aniso-accommodation. This conclusion is strengthened by the previous finding of long reaction and response times, 11 and 15s respectively, to step aniso-accommodative stimuli (Marran and Schor, Vision Res.38(22), 3601–3619). Since the experimental target provided subjects with visual feedback of the relative blur of the dichoptically viewed letters, subjects had access to perceptual blur information cues. Some subjects seemed to have required both aniso-blur and proximity to exercise this volitional response. Those subjects who showed a distance invariant aniso-accommodative response may have been able to use perceived aniso-blur alone and their ability to disregard proximal cues may have resulted from greater experience with the aniso-accommodative stimuli. Alternatively, these subjects may have had a lower threshold to proximal stimuli and experienced target proximity at the more distant (1m) viewing condition.

Reliability of a New Instrument to Measure Scapular Position

The purpose of this study was to develop an objective method to measure scapular position as it relates to the frontal, sagittal and transverse reference planes of the human body. Contemporary shoulder rehabilitation programs place great emphasis on the role of the scapula in the treatment of shoulder pathology. While clinicians employ many treatment techniques aimed at improving scapular function, a literature review reveals that clinicians lack objective measurement techniques to measure scapular position. A Scapular Measurement Instrument (SMI) was used to objectify scapular position. Eleven subjects, who reported no current history of shoulder pain or pathology, were included in the study. Testers obtained measurements of scapulae position with respect to the frontal, sagittal, and transverse planes of the body. Inferior angle scapular measurements (IAM) and spine of the scapula measurements (SM) were taken. Two test positions were used. Position 1 was termed the “rest position” and involved subjects sitting with their arms resting at their side; position 2 involved subjects placing their arms in a “reach position” touching their opposite shoulder blade. Statistical analysis was carried out in an attempt to estimate reliability. Intratester and intertester correlation coefficients (ICC), and Standard Error of Measurement (SEM) values were calculated for all measurements. In an attempt to validate the frontal and sagittal plane referenced measurements, subjects' scapulae positions were quantified via radiographic (x-ray) analysis. Pearson Moment Correlation Coefficients were used to assess the measurement relationships between x-ray and (SMI) obtained values. Intratester ICC values for the rest condition ranged from .68 to .88 (IAM) and .68 to 86 (SM). Intratester ICC values for the reach condition ranged from .51 to .91 (IAM) and .60 to .95 (SM). Intertester ICC values for the rest condition ranged from .68 to .80 (IAM) and .80 to .95 (SM), and intertester ICC for the reach condition ranged from .48 to .66 (IAM) and .30 to .86 (SM). These values indicate better reliability for the rest condition. Intratester reliability values were generally greater than intertester values. SEM was 1 cm or less for all measurements. In regard to the validation of testers' measurements via x-ray, Pearson Moment Correlation Coefficients revealed a general trend of greater validity for rest versus reach conditions. Rest-condition correlation data ranged from .87 to .96, while reach-condition correlation data ranged from .23 to .93. The large range in correlation data was believed to be representative of random error of measurement. The authors feel that this technique is a viable option for objective measurement of at-rest scapular position. Further research is suggested, including refinement of the SMI and investigation into alternative radiographic and measurement procedures.

Textural Property Considerations of Food for Dysphagia

Food and liquid textures play very important roles in the care of people with dysphagia. However, a major source of frustration for those involved with the patient is how to determine, describe, and deliver the proper textures of foods and liquids. The science of food rheology offers the potential to establish standardized food textures using objective measurement techniques. This article covers the basic physical forces of chewing and swallowing, standard food‐texture terminology, textures of interest in dysphagia, selection of physical measurement methods and instruments, and techniques to determine the boundaries between the levels of the dysphagia diet.

The effect of target proximity on the aniso-accommodative response.

Aniso-accommodation (unequal binocular accommodation) to lens-induced anisometropia has been demonstrated by subjective and objective measurement techniques (Marran and Schor, Vision Res. 38(22), 3601-3619). The gain of the response was significantly reduced for some subjects when aniso-accommodation was stimulated by a target at 1 m compared to a target at 20 cm, even when the targets viewed were matched in retinal image size, convergence levels and aniso-accommodative stimuli. The two conditions did differ in both the accommodative level and proximity of the target. Thus the higher gain of the response in the 20 cm condition could have arisen from either high proximity, high accommodative level or a combination of both. In this investigation, target proximity and accommodative level were manipulated independently while extra-retinal cues such as absolute disparity and image size were held constant. The results show that high target proximity alone rather than accommodative level or a combination of the two was responsible for the distance dependent effect demonstrated by subjects. Furthermore, accommodative level did not affect the response when target proximity was held constant. Subjects who demonstrated invariant aniso-accommodation with changes in viewing distance also demonstrated invariant aniso-accommodation with experimental manipulation of target proximity at the target distances tested, as would be expected. These results suggest that high level processing, rather than a reflex blur response, is involved in aniso-accommodation. This conclusion is strengthened by the previous finding of long reaction and response times, 11 and 15 s respectively, to step aniso-accommodative stimuli (Marran and Schor, Vision Res. 38(22), 3601-3619). Since the experimental target provided subjects with visual feedback of the relative blur of the dichoptically viewed letters, subjects had access to perceptual blur information cues. Some subjects seemed to have required both aniso-blur and proximity to exercise this volitional response. Those subjects who showed a distance invariant aniso-accommodative response may have been able to use perceived aniso-blur alone and their ability to disregard proximal cues may have resulted from greater experience with the aniso-accommodative stimuli. Alternatively, these subjects may have had a lower threshold to proximal stimuli and experienced target proximity at the more distant (1 m) viewing condition.

Identifying parameters of improvement in voice disorders by use of objective measurement techniques

ABSTRACT For many years the assessment, evaluation, diagnosis and treatment of voice disorders has included objective measurement techniques as well as many subjective assessments of respiratory and vocal function. This study was established to look into objective measurement as a means of monitoring change within various diagnostic groups of dysphonic patients, using two hospital departments in different locations and comparing the results of clinical data from dysphonia assessments and re‐assessments at approximately 6‐week intervals. The data was collated from the caseload of 10 therapists with experience in the management of dysphonia. It was hoped that the analysis would confirm: (1) Patterns of measureable improvements in different parameters for dysphonia of different aetiologies; (2) Outcome measures for the different aetiological groups in terms of laryngeal condition and voice quality, mean numbers of sessions and weeks. The two centres, Law Hospital NHS Trust (LH) and the Victoria Infirmary NHS Trust (VI), operate similar voice assessment clinic and videostroboscopy procedures and are equipped with similar systems of computer‐assisted instrumentation, i.e. ST1 airflow measurement, Visispeech and the portable electrolaryngograph (ELG). A population sample was carried out at each centre to determine normative values for Visispeech and ELG, in recognition of the variation caused by clinical situations, microphones and user technique. No sampling was necessary for the ST1 airflow instrument (Kelman et al., 1975). The samples included 43 female and 47 male subjects (LH) and 62 females and 21 males (VI). The patient sample involved 67 patients at VI and 70 at LH. Patients were grouped according to the laryngeal diagnosis as follows: vocal strain; oedema; vocal nodules; post‐surgical; ventricular folds; psychogenic; bowing; post‐radiotherapy; contact ulcers; and vocal cord palsy. Patients were treated by therapists within their clinical workload, using their treatment of choice and determining the frequency, length and number of sessions according to their usual procedures. No therapy technique was prescribed and no timescale stated. It was felt that if similar objective results were produced at the two centres, the results could be accepted as indicatng the most vital parameters requiring change to facilitate maximal improvement. Objective assessments confirmed similar results between the two centres in the following: (1) Certain diagnostic groups showed the same parameters to be within normal limits at the initial assessment; (2) Specific parameters were identified in certain diagnostic groups as those showing most change towards normal limits; (3) Different diagnostic groups showed different patterns of normality and change. There were also close similarities in the numbers of treatment sessions and total length of care episode. Having identified the parameters of normality and required change for different diagnostic groups, it may follow that targeting these key areas in therapy will result in maximal improvement in laryngeal condition and voice quality, with efficient use of time and resources. This would have important implications in future objective assessments of dysphonia and planning of appropriate therapy.

Peer group counselling with bereaved adolescents

Abstract An experiment is described which aimed to help bereaved teenagers through peer group counselling, and also to examine the related issue of how reliably we can measure the effectiveness of such counselling. This involved a systematic approach to the subjective impressions of participants, and also used objective measurement techniques. Subjects perceived the group counselling sessions to have had a high value, and certain consistent trends were revealed concerning participants' previous experience of their bereavement and concerning the medium-term effects of adolescent bereavement. Statistical analysis of the objective tests paralleled this with improvements in several areas, though the extent of the statistical significance of those improvements is debatable. Recommendations are made concerning the implications for the pastoral care of bereaved pupils in schools.

Peer Group Counselling with Bereaved Adolescents

Abstract An experiment is described which aimed to help bereaved teenagers through peer group counselling, and also to examine the related issue of how reliably we can measure the effectiveness of such counselling. This involved a systematic approach to the subjective impressions of participants, and also used objective measurement techniques. Subjects perceived the group counselling sessions to have had a high value, and certain consistent trends were revealed concerning participants' previous experience of their bereavement and concerning the medium-term effects of adolescent bereavement. Statistical analysis of the objective tests paralleled this with improvements in several areas, though the extent of the statistical significance of those improvements is debatable. Recommendations are made concerning the implications for the pastoral care of bereaved pupils in schools.

Daylight as a zoning device for midtown

Since 1960, New York City's Midtown district has experienced an office building boom with the construction of seventy million square feet (650 300 m 2) of new office space in one hundred eleven buildings. During this period it became increasingly clear that this new generation of superscale office towers, such as AT & T and IBM, were overpowering their context by dramatically diminishing the daylighting available to the public streets, parks, plazas, and neighboring buildings. The prime cause of this environmental dilemma was the permissive and subjective manner in which the City Planning Commission reviewed Midtown buildings. The waiving of the rigid as-of-right or automatic height and setback regulations for a negotiated review, conceived to encourage good architecture, resulted in daylighting conditions which were measurably worse than those that, in part, led to the call for zoning to protect public access to “light and air” in 1916. The as-of-right zoning regulations which were enacted to guarantee an adequate level of solar access had been superceded by negotiated or discretionary zoning and in the process one of the original goals of zoning was lost. Responding to the defined need for procedural certainty, public accountability, and design and development flexibility, the consultants proposed a performance system of as-of-right zoning based on objective criteria and measurement techniques. The centerpiece of the new building bulk regulations is a modified Waldram Diagram on which the daylighting performance of a building is evaluated against a threshold and standard. The threshold and standard were systematically derived from an analysis of the sixty-year historical expectation for daylight in Midtown. The performance system as adopted by the City is presently being programmed for computer evaluation.

The formatting of alphanumeric displays: a review and analysis.

This paper surveys the literature on alphanumeric display formatting, focusing primarily on computer-generated displays. Two general areas are included: guidelines addressing display design and empirical studies of displays. Four characteristics of display formats are described: overall density, local density, grouping, and layout complexity. Objective measurement techniques for these characteristics are proposed and are applied to two different display formats. The results suggest that these measures could provide the basis for objectively evaluating a display without collecting performance data.

Speech intelligibility in rooms

This paper reviews developments in the science of speech intelligibility in rooms, and discusses the need for further work. Over the last 60 years, knowledge on this subject area of auditorium acoustics has been ascertained by observation and experiment, critically tested, systematized, and brought under a set of general principles. Objective indices are now available for measuring and predicting speech intelligibility in rooms without the need for traditional subjective testing procedures. Thus a more widespread application of intelligibility criteria in auditorium design is to be expected in future work. Parallel with the developments in objective and subjective measurement techniques, the computer prediction of reflection patterns in rooms has been developed so that speech intelligibility levels can now be ascertained during design, and acoustic faults remedied before construction commences. However, further work is needed to establish a valid basis for speech intelligibility design criteria based on objective measurements. To this end, a catalog of subjective and objective measures of speech intelligibility could be determined for a set of conditions in well‐known auditoria. The result would be a relative scale of intelligibility values for use by practitioners. [Work supported by the SERC, United Kingdom.]