Ergonomic aspects of aircraft keyboard design: the effects of gloves and sensory feedback on keying performance

Increasing requirements for aircraft keyboards have indicated inadequacies in ergonomic standards for airborne environments, in particular for tasks involving unskilled, discontinuous data entry, with emphasis on accuracy rather than speed. Four experiments are reported from a programme of research aimed at the development and application of methodologies for assessing factors relevant to keyboard design. Experiment 1 demonstrated that the effects of various aircrew gloves on a representative aircraft data entry task are highly situation specific. Experiment 2 showed that gloves impaired performance on a high compatibility continuous keying task, with relatively high keying rates, and that this impairment was not reduced by additional auditory feedback. Experiment 3 demonstrated that the high compatibility keying task provided a successful methodology for investigating the effects of key displacement and resistance on speed and accuracy. Experiment 4 indicated the relative contributions of reduced tactility and mobility to the effects on keying and manipulative performance caused by aircrew gloves. Together, these experiments suggest that kinaesthetic and tactile feedback associated with keying are relatively unaffected by aircrew gloves, and that restrictions on mobility caused by gloves may be more important for continuous data entry involving relatively high keying rates     

Judging the urgency of non-verbal auditory alarms: a case study

When designed correctly, non-verbal auditory alarms can convey different levels of urgency to the aircrew, and thereby permit the operator to establish the appropriate level of priority to address the alarmed condition. The conveyed level of urgency of five non-verbal auditory alarms presently used in the Canadian Forces CH-146 Griffon helicopter was investigated. Pilots of the CH-146 Griffon helicopter and non-pilots rated the perceived urgency of the signals using a rating scale. The pilots also ranked the urgency of the alarms in a post-experiment questionnaire to reflect their assessment of the actual situation that triggers the alarms. The results of this investigation revealed that participants' ratings of perceived urgency appear to be based on the acoustic properties of the alarms which are known to affect the listener's perceived level of urgency. Although for 28% of the pilots the mapping of perceived urgency to the urgency of their perception of the triggering situation was statistically significant for three of the five alarms, the overall data suggest that the triggering situations are not adequately conveyed by the acoustic parameters inherent in the alarms. The pilots' judgement of the triggering situation was intended as a means of evaluating the reliability of the alerting system. These data will subsequently be discussed with respect to proposed enhancements in alerting systems as it relates to addressing the problem of phase of flight. These results call for more serious consideration of incorporating situational awareness in the design and assignment of auditory alarms in aircraft.     

Laser projection versus a CRT display in the visual perception of aircraft aspect

High-resolution visual displays have been designed for flight simulation so that observers may judge the aspect angle of aircraft at far distances. The present experiment compares two display devices as untrained observers judge the spatial orientation of two target aircraft: F-15 and F-16 jets. The display devices are a prototype direct-write microlaser projector and an SXGA-format CRT display. Observers' accuracy of aircraft identification is better with the laser projector, and recognition response times are faster. A simple rule was found to fit the observers' response times; it is expressed in terms of a statistic on the autocorrelation of black-and-white silhouette images of aircraft. Observers' estimates of aspect are biased by the laser projector, whereas observers' estimates of aspect are accurate on average with the SXGA display. This bias in estimation of aspect may be attributable to variations in line brightness introduced by the laser projector. Actual or potential applications of this research include the evaluation of high-resolution visual displays for the training of basic fighter maneuvers with military jet pilots.     

Changing the role of the air traffic controller: how will free flight affect memory for spatial events?

At present, air traffic controllers (ATCOs) exercise strict control over routing authority for aircraft movement in airspace. The onset of a free flight environment, however, may well result in a dramatic change to airspace jurisdictions, with aircraft movements for the large part being governed by aircrew, not ATCOs. The present study examined the impact of such changes on spatial memory for recent and non-recent locations of aircraft represented on a visual display. The experiment contrasted present conditions, in which permission for manoeuvres is granted by ATCOs, with potential free flight conditions, in which aircrew undertake deviations without explicit approval from ATCOs. Results indicated that the ATCO role adopted by participants impacted differently on short-term and long-term spatial representations of aircraft manoeuvres. Although informing participants of impending deviations has beneficial effects on spatial representations in the short term, long-term representations of spatial events are affected deleteriously by the presentation of subsequent information pertaining to other aircraft. This study suggests strongly that recognition of the perceptual and cognitive consequences of changing to a free flight environment is crucial if air safety is not to be jeopardized.     

Effects of pyridostigmine bromide on in-flight aircrew performance

The effects of a chemical defense pretreatment drug, pyridostigmine bromide (PB), on in-flight aircrew performance were assessed using the Total In-Flight Simulator (TIFS) aircraft. TIFS was used to supply appropriate control dynamics, handling characteristics, and cockpit instrumentation for a tactical transport airdrop simulation. Twenty-one C-130 pilots flew two familiarization and four data flights. During two data flights PB was given to both members of the aircrew using the dosage regimen of 30 mg/8 h prescribed by the U.S. Air Force surgeon general. The drug was administered using a double-blind technique. The results indicated that (1) aircrews successfully completed their assigned mission, (2) airdrop inaccuracies and navigation errors in time and distance were not specifically related to PB, (3) performance and crew coordination were not affected by PB, (4) PB and pilot/copilot not discriminate beyond chance between PB and placebo conditions.     

Judging the urgency of non-verbal auditory alarms: a case study

When designed correctly, non-verbal auditory alarms can convey different levels of urgency to the aircrew, and thereby permit the operator to establish the appropriate level of priority to address the alarmed condition. The conveyed level of urgency of five non-verbal auditory alarms presently used in the Canadian Forces CH-146 Griffon helicopter was investigated. Pilots of the CH-146 Griffon helicopter and non-pilots rated the perceived urgency of the signals using a rating scale. The pilots also ranked the urgency of the alarms in a post-experiment questionnaire to reflect their assessment of the actual situation that triggers the alarms. The results of this investigation revealed that participants' ratings of perceived urgency appear to be based on the acoustic properties of the alarms which are known to affect the listener's perceived level of urgency. Although for 28% of the pilots the mapping of perceived urgency to the urgency of their perception of the triggering situation was statistically significant for three of the five alarms, the overall data suggest that the triggering situations are not adequately conveyed by the acoustic parameters inherent in the alarms. The pilots' judgement of the triggering situation was intended as a means of evaluating the reliability of the alerting system. These data will subsequently be discussed with respect to proposed enhancements in alerting systems as it relates to addressing the problem of phase of flight. These results call for more serious consideration of incorporating situational awareness in the design and assignment of auditory alarms in aircraft.     

飞机排班调度中机组指派优化模型及算法研究

分析了航空企业飞机排班计划编制流程,重点研究了其中的空勤机组指派优化问题,建立了机组指派优化模型,模型同时考虑了机组与航班执行飞机之间在机型、飞行区域等条件上的匹配要求。为求解模型,构造了一种改进遗传算法,算法采用自然数编码,动态自适应调整交叉和变异概率,以及智能启发式规则修正的方式加快优化速度。采用航空公司的实际航班数据进行仿真实例研究结果表明,模型和算法切实可行。     

Adaptive control laws for F-8 flight test

This paper describes an adaptive flight control system design for NASA's F-8 digital fly-by-wire research aircraft. This design implements an explicit parallel maximum likelihood identification algorithm to estimate key aircraft parameters. The estimates are used to compute gains in simplified quadratic-optimal command augmentation control laws. Design details for the control laws and identifier are presented, and performance evaluation results from NASA Langley's F-8 Simulator are summarized.     

Cough once for danger: icons versus abstract warnings as informative alerts in civil aviation

OBJECTIVE: An experiment investigated the efficacy of auditory icons as warning signals in an aviation context. BACKGROUND: Iconic signals, such as a cough to signal dangerous levels of carbon monoxide, convey information about the nature of an incident and alert the operator that there is a problem, whereas signals that are arbitrarily associated with a critical incident provide relatively less information. Warning recognition speed and accuracy are likely to be influenced by modality of presentation (visual, auditory, auditory + visual) and task demand (low, high). METHODS: The 172 participants completed a computer-based training session and test task that involved responding to abstract or iconic auditory (1 s), visual, or auditory + visual warnings associated with seven critical incidents while performing low- and high-demand concurrent tasks. RESULTS: Significantly fewer training trials were required to learn iconic warnings than abstract warnings. An advantage for iconic warnings persisted into the test phase, evident most consistently as greater warning recognition accuracy. The effect was observed in both high- and low-demand conditions. Auditory abstract warnings, in particular, elicited slow reaction times and poor accuracy. CONCLUSION: Associations between a small number of meaningful environmental sounds and critical incidents can be learned with ease relative to more abstract associations, although training is required and response times are relatively slow. APPLICATION: Sets of distinctive auditory iconic warnings can be designed to alert and inform pilots about non-time-pressured events. Potential applications of language-neutral icons as informative warnings include civil, commercial, and defense aircraft.     

An overview of auditory display to assist comprehension of molecular information

This paper presents an overview of auditory display (the use of non-speech sounds to convey information) applied to the study of molecular properties in human–computer interfaces, particularly in virtual environments. Chemistry researchers and students have difficulty in analysing and comprehending molecular structure and bonding and other biomolecular characteristics. Research reports that non-speech sounds have been useful in identifying trends in gene sequences and molecular characteristics, which when used in virtual environments, can facilitate comprehension of complex relationships that are difficult to perceive through visualisation alone.     

Auditory navigation in hyperspace: design and evaluation of a non-visual hypermedia system for blind users

This paper presents the design and evaluation of a hypermedia system for blind users, making use of a nonvisual interface, non-speech sounds, three input devices, and a 37 node hypermedia module. The important components of an effective auditory interface are discussed, together with the design of the auditory interface to hypermedia material. The evaluation, which was conducted over several weeks and used a range of complementary objective and subjective measures to assess users' performance and preferences, is described. The findings from the evaluation with nine visually impaired student participants are presented. The results from this research can be applied to the design and evaluation of other non-visual hypermedia systems, such as auditory World Wide Web (WWW) browsers and digital talking books.     

Psychophysiological response of different aircrew in normobaric hypoxia training

Abstract

Hypoxia remains the most important hazard in high altitude flights, but there is still a need for deeper analysis of the effect of hypoxia exposition in the psychophysiological and cognitive functions. The aim of this study was to study the effect of hypoxia training in cortical arousal, autonomic modulation, muscle strength and cognitive function. We analysed 23 male aircrew personnel of the Spanish Army and Air Force (10 Helicopter Pilots, 7 Transport Aircrew, 3 Transport Pilots and 3 F-18 Fighter Pilots) before, during and after a normobaric hypoxia exposition. Hypoxia produced an increase in perceived stress and effort, a higher Heart Rate and a decreased function of breath muscles. Working memory and pattern recognition were impaired after hypoxia exposition. Significant differences were found in cognitive tests performance among aircrew groups, suggesting differences on their previous training. These results can improve specific training for better preparation of pilots and aircrews for hypoxic threats.

Practitioner summary: Distinct aircrew preparation produces a different hypoxia exposition effect on psychophysiological response and cognitive functions. Hypoxia produced an increase in Heart Rate, a decreased function of breath muscles, being more negatively affected in Transport Pilots. Cognition abilities were impaired after hypoxia exposition, independently of the aircrew group.     

Pilot mental workload: how well do pilots really perform?

The purpose of this study was to investigate the effects of increasing mental demands on various aspects of aircrew performance. In particular, the robustness of the prioritization and allocation hierarchy of aviate–navigate–communicate was examined, a hierarchy commonly used within the aviation industry. A total of 42 trainee pilots were divided into three workload groups (low, medium, high) to complete a desktop, computer-based exercise that simulated combinations of generic flight deck activities: flight control manipulation, rule-based actions and higher level cognitive processing, in addition to Air Traffic Control instructions that varied in length from one chunk of auditory information to seven chunks. It was found that as mental workload and auditory input increased, participants experienced considerable difficulty in carrying out the primary manipulation task. A similar decline in prioritization was also observed. Moreover, when pilots were under a high mental workload their ability to comprehend more than two chunks of auditory data deteriorated rapidly.     

Pilot mental workload: how well do pilots really perform?

The purpose of this study was to investigate the effects of increasing mental demands on various aspects of aircrew performance. In particular, the robustness of the prioritization and allocation hierarchy of aviate-navigate-communicate was examined, a hierarchy commonly used within the aviation industry. A total of 42 trainee pilots were divided into three workload groups (low, medium, high) to complete a desktop, computer-based exercise that simulated combinations of generic flight deck activities: flight control manipulation, rule-based actions and higher level cognitive processing, in addition to Air Traffic Control instructions that varied in length from one chunk of auditory information to seven chunks. It was found that as mental workload and auditory input increased, participants experienced considerable difficulty in carrying out the primary manipulation task. A similar decline in prioritization was also observed. Moreover, when pilots were under a high mental workload their ability to comprehend more than two chunks of auditory data deteriorated rapidly.     

Continuous sonification enhances adequacy of interactions in peripheral process monitoring

As many users who are charged with process monitoring need to focus mainly on other work while performing monitoring as a secondary task, monitoring systems that purely rely on visual means are often not well suited for this purpose. Sonification, the presentation of data as (non-speech) sound, has proven in several studies that it can help in guiding the user's attention, especially in scenarios where process monitoring is performed in parallel with a different, main task. However, there are several aspects that have not been investigated in this area so far, for example if a continuous soundscape can guide the user's attention better than one that is based on auditory cues. We have developed a system that allows reproducible research to answer such questions. In this system, the participants’ performance both for the main task (simulated by simple arithmetic problems) and for the secondary task (a simulation of a production process) can be measured in a more fine-grained manner than has been the case for existing research in this field. In a within-subject study (n=18), we compared three monitoring conditions – visual only, visual + auditory alerts and a condition combining the visual mode with continuous sonification of process events based on a forest soundscape. Participants showed significantly higher process monitoring performances in the continuous sonification condition, compared to the other two modes. The performance in the main task was at the same time not significantly affected by the continuous sonification.     

The contribution of communications signals to noise exposure

Man-mounted miniature recording equipment has been used to measure the electroacoustic conditions obtaining in cockpits of aircraft and at the pilot's ear during operational sorties in the Royal Air Force. Although this paper considers the measurements taken that relate to the total noise exposure (noise dose) received by aircrew, the results apply equally to anyone who is exposed to high noise and requires communications.

Comparison of the noise at the ear with the cockpit noise gave a measure of headgear attenuation which was used to adjust a 1/3-octave filter. Playing cockpit noise tapes through this filter to a noise dose meter gave the noise dose that would have been experienced had there been no communications signals. The results showed that the communications signals at the ear, averaging 40% of the sortie time, are a major contributor to the total dose, and, without the signals, the dose averaged about 6 dB less. In view of the Health and Safety at Work Act, 1974, employers should be aware of the additional dose to which employees are exposed because of communications.

A method for the prediction of noise dose is proposed where communication takes place in a noisy environment.     

Using non-speech sound to overcome information overload

With ever increasing amounts of visual information to take in when interacting with computers, users can become overloaded. One reason is that computers communicate solely by graphical output. This paper suggests the use of non-speech sound output to enhance the graphical display of information to overcome overload. The question is how to integrate the display of sound and graphics to capitalise on the advantages each offers. The approach described here is to integrate sound into the basic components of the human-computer interface. Two experiments are described where non-speech sounds were added to buttons and scrollbars. Results showed sound improved usability by increasing performance and reducing time to recover from errors. Subjective workload measures also showed a significant reduction. Results from this work show that the integrated display of graphical and auditory information can overcome information overload.     

音频取证中录音设备识别研究进展

从音频信号中提取录音设备特征是司法比较研究和音频取证的前沿课题。由于录音设备识别技术受到环境、语义、说话人等因素干扰,需要攻克的难题较多,国内外的研究还处于起步阶段。为此回顾了录音设备研究的发展情况、基本理论和组成结构,特别对组成结构中非话音段检测、特征参数、识别模型和数据库建设的研究现状进行了介绍和分析。最后,进一步分析了录音设备识别存在的不足,并展望未来的研究发展方向,指出加快构建现有各品牌各型号的录音设备、各场合、各类人群的数据库建设与深度学习在录音设备中的应用是下一阶段研究的重点。     

基于FFT的非均匀重采样值的重构实现技术

文章叙述数字语音信号的基于FFT的非均匀重采样值重构的技术实现问题,并对实际的WAV格式的数字语音文件的重采样值用VC++6.0编写的程序实现了基于FFT的重构;以实验数据结果分析讨论了重构信号的质量、重采样后的数据量与分段长度的关系等问题;实现方法、实现程序及结论不仅对WAV格式的数字语音文件有效,而且也适用于其它格式的数字语音文件和非语音信号的非均匀采样值重构的实现。