Browsing by Author "Morrison, H. Boyd"

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    The influence of depth and stutter on consumer preference for static three-dimensional lenticular-sheet images
    Morrison, H. Boyd (Virginia Tech, 1995)
    Lenticular-sheet (LS) images induce the sensation of object depth through motion parallax and stereopsis, which is based on retinal disparity. To achieve the three-dimensional effect, some sacrifice of image quality must be made. A study is described which investigated the tradeoff between depth and image quality that is inherent in LS imaging by asking subjects to evaluate stimuli that varied on these attributes. Four different scenes were generated as experimental stimuli to encompass a range of typical LS images. The length of camera travel in taking the 20 photographs necessary to produce a single image determined the overall amount of depth in the image, while varying the pivot point allowed the degree of foreground and background disparity to be altered. Preference evaluations were conducted using the method of free-modulus magnitude estimation. Generally, subjects preferred images which had smaller amounts of camera travel, and they tended to dislike excessive amounts of foreground disparity. However, differences were scene-dependent, so post-hoc analyses were performed to determine sources of significance in main effects and interactions. The most preferred image was also determined for each scene by selecting the image with the highest mean rating. In a second experiment, these most preferred LS images for each scene were shown to subjects along with their analogous two-dimensional (2D) photographic versions. Results indicate that observers from the general population looked at the LS images longer than they did at the 2D versions and rated them higher on the attributes of quality of depth and attention-getting ability, although the LS images were rated lower on sharpness. No difference was found in overall quality or likeability. When paired comparisons were made, preference results were scene-dependent. Finally, a recall task showed no difference in the ability to remember details based on the type of image. These results show that consumers prefer LS images when they satisfy the viewer’s image quality requirements and that these images can be beneficial in attracting and maintaining consumer attention. Recommendations, in the form of design implications, are made which can help the LS image developer meet these image quality requirements.
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    Intelligibility of synthesized voice messages in commercial truck cab noise for normal-hearing and hearing-impaired listeners
    Morrison, H. Boyd (Virginia Tech, 1993)
    A human factors experiment was conducted to assess the intelligibility of synthesized speech under a variety of noise conditions for both hearing-impaired and normal-hearing subjects. Modified Rhyme Test stimuli were used to determine intelligibility in four speech-to-noise (S/N) ratios (0, 5, 10, and 15 dB), and three noise types, consisting of flat-by-octaves (pink) noise, interior noise of a currently produced heavy truck, and truck cab noise with added background speech. A quiet condition was also investigated. During recording of the truck noise for the experiment, in-cab noise measurements were obtained. According to OSHA standards, these data indicated that drivers of the sampled trucks have a minimal risk for noise-induced hearing loss due to in-cab noise exposure when driving at freeway speeds because noise levels were below 80 dBA. In the intelligibility experiment, subjects with hearing loss had significantly lower intelligibility than normal-hearing subjects, both in quiet and in noise, but no interaction with noise type or S/N ratio was found. Intelligibility was significantly lower for the noise with background speech than the other noises, but the truck noise produced intelligibility equal to the pink noise. An analytical prediction of intelligibility using Articulation Index calculations exhibited a high positive correlation with the empirically obtained intelligibility data for both groups of subjects.