A database of speech samples from eight different talkers has been collected for use in multitalker communications research. Descriptions of the nature of the corpus, the data collection methodology, and the means for obtaining copies of the database are presented.

We conducted an experiment to evaluate the effectiveness of spatial audio displays on target acquisition performance. Participants performed a visual search task with and without the aid of a spatial audio display. Potential target locations ranged between plus and minus 180° in azimuth and from -70° to +90° in elevation. Independent variables included the number of visual distractors present (1,5, 10, 25, 50) and the spatial audio condition (no spatial audio, free-field spatial audio, virtual spatial audio). Results indicated that both free-field and virtual audio cues engendered a significant decrease in search times. Potential applications of this research include the design of spatial audio displays for aircraft cockpits and ground combat vehicles.

Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing this collection of information. Send comments regarding this burden estimate or any other aspect of this collection of Information, including suggestions for reducing this burden to Department of Defense, Washington Headquarters Services, Directorate for Information Operations and Reports (0704-0188), 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to any penalty for failing to comply with a collection of information if it does not display a currentiy valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. REPORT DATE SPONSORING / MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSOR/MONITOR'S ACRONYM(S)AFLR/HECB SPONSOR/MONITOR'S REPORT NUMBER(S) DISTRIBUTION I AVAILABILITY STATEMENTApproved for public release; distribution is unlimited. SUPPLEMENTARY NOTESOriginally published in the journal Human Factors, Spring 2005.14. ABSTRACTThe effect of hearing protection devices (HPDs) on sound localization was examined in the context of an auditorycued visual search task. Participants were required to locate and identify a visual target in a field of 5, 20, or 50 visual distractors randomly distributed on the interior surface of a sphere. Four HPD conditions were examined: earplugs, earmuffs, both earplugs and earmuffs simultaneously, and no hearing protection. There was also a control condition in which no auditory cue was provided. A repeated measures analysis of variance revealed significant main effects of HPD for both search time and head motion data, indicating that the degree to which localization is disrupted by HPDs varies with the type of device worn. When both earplugs and earmuffs are worn simultaneously, search times and head motion are more similar to those found when no auditory cue is provided than when either earplugs or earmuffs alone are worn, suggesting that sound localization cues are so severely disrupted by double hearing protection that the listener can recover little or no information regarding the direction of sound source origin. Potential applications of this research include high-noise military, aerospace, and industrial settings in which HPDs are necessary but wearing double protection may compromise safety and/or performance. The effect of hearing protection devices (HPDs) on sound localization was examined in the context of an auditory-cued visual search task. Participants were required to locate and identify a visual target in a field of 5, 20, or 50 visual distractors randomly distributed on the interior surface of a sphere. Four HPD conditions were examined: earplugs, earmuffs, both earplugs and earmuffs simultaneously (double hearing protection), and no hearing protection. In addition, t...

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Advances in helmet-mounted displays (HMDs) have permitted the design of "see-through" displays in which virtual imagery may be superimposed upon real visual environments. Such displays have numerous potential applications; however, their promise to improve human perception and performance in complex task environments is threatened by numerous technological challenges. Moreover, users of HMDs may be vulnerable to symptoms associated with simulator sickness. The primary objective of this investigation was to assess subjective ratings of simulator sickness as a function of time delay, time on task, and task complexity. Participants attempted to center a reticle over a moving circular target using a see-through HMD while concurrently performing a visual monitoring task displayed on a computer monitor. Results indicated that simulator sickness ratings varied directly with time on task, while performance efficiency and ratings of perceived mental workload were not mediated by this factor. Furthermore, the time delay manipulation that affected performance efficiency and operator workload did not generally influence SSQ ratings. These findings are discussed in terms of their implications for practical implementation of see-through HMDs in multi-task environments.

Automatic speech emotion recognition (SER) techniques based on acoustic analysis show high confusion between certain emotional categories. This study used an indirect approach to provide insights into the amplitude-frequency characteristics of different emotions in order to support the development of future, more efficiently differentiating SER methods. The analysis was carried out by transforming short 1-second blocks of speech into RGB or grey-scale images of spectrograms. The images were used to fine-tune a pre-trained image classification network to recognize emotions. Spectrogram representation on four different frequency scales-linear, melodic, equivalent rectangular bandwidth (ERB), and logarithmic-allowed observation of the effects of high, mid-high, mid-low and low frequency characteristics of speech, respectively. Whereas the use of either red (R), green (G) or blue (B) components of RGB images showed the importance of speech components with high, mid and low amplitude levels, respectively. Experiments conducted on the Berlin emotional speech (EMO-DB) data revealed the relative positions of seven emotional categories (anger, boredom, disgust, fear, joy, neutral and sadness) on the amplitudefrequency plane.

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An experiment was conducted to determine the effects of two types of hearing protectors on auditory localization performance. Six listeners localized a 750-ms broadband noise from loudspeakers ranging in azimuth from -180 degrees to +180 degrees and in elevation from -75 degrees to +90 degrees. Independent variables included the type of hearing protector and the elevation of the source. Dependent measures included azimuth error, elevation error, and the percentage of trials resulting in a front-back confusion. Performance on each of the dependent measures was found to be mediated by one or more of the independent variables. Actual or potential applications include the generation of improved design guidelines for hearing protectors and workplace alarms.