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The proprietary product of Coulter Information Systems, designated KC-Film, will be described in terms of physical makeup, operating characteristics and areas of application. KC-Film is a crystalline, transparent photoconductor made up of semiconductors so tiny that the layer contains 100 million to the square millimeter. The surface voltages utilized with KC-Film are very much lower than normally found in electrophotographic recording work. This results in the ability to produce extended grey scale continuous tone imagery without edge effects. KC-Film has sensitivity comparable to high resolution silver halide films and has spectral sensitivity throughout the visible region. The application possibilities demonstrated to this time include high resolution continuous tone imagery, offset, printing, high speed contact printing, microfilming, plain paper copying, and multi-megacycle laser recording. Presently available coating capability allows production of films up to 32 inches wide by 4000 feet long.© (1977) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Loudness is unusually stable. Unlike most other sensations, it does not decline over time simply as the result of continued stimulation. The failure of loudness to adapt under most listening conditions poses an intriguing question. Just what keeps loudness from adapting? To help answer that question, we have investigated two of those conditions under which loudness does adapt, at levels below about 30 dB SL (Scharf, 1983) and in the presence of a contralateral intermittent sound (Botte et al., 1982). The present paper extends the latter investigation. First we review the phenomenon which we have called induced loudness adaptation and present new data on the effect of intermittency. Second we examine the reduction in the loudness of a continuous tone while a 10-s tone is present in the contralateral ear; particular attention is paid to frequency selectivity. Third we show that loudness adaptation can be induced by an intermittent tone in the same ear(s) as the continuous tone, whether the tones are presented through earphone(s) or from loudspeaker(s) in a free field.

Frequency-following responses (FFR) from continuous tone stimulation were investigated by lock-in analysis. The technique is superior to conventional tone-burst stimulation, because it allows continuous registration of the response parameters with sweeping frequency. The scalp recorded FFR consists of at least two components separable from each other by their phase/frequency relationship. The microphonic component that dominates in ipsilateral records shows latencies of about 0.5 msec with negligible dispersion and must therefore originate in the basal cochlear turn. The neural component exhibits considerable dispersion, reflecting the travelling wave delay up to the region of best frequency. These long cochlear time delays are consistent with an apical FFR origin, and brain stem sources of the continuous tone response appear to be questionable. The present FFR analysis technique opens up a very direct and comprehensive way to assess the integrity of the entire inner ear for high frequency basal and low frequency apical cochlear regions as well.

With advances in our understanding of the auditory periphery, models of cochlear mechanics have evolved from descriptions of existing data to the point that they can suggest meaningful observations that should be made and predict expected outcomes. As an example, we discuss relationships among mechanical nonlinearities in the inner ear, two‐tone suppression, and the auditory “second filter.” Electrophysiological two‐tone suppression data indicate that excitatory tuning curves (stimulus intensity required to elicit a specified amount of activity in a primary fiber, as a function of frequency) are more sharply tuned than suppressive tuning curves (stimulus intensity required to suppress the response to a continuous tone at the fiber's characteristic frequency by a specified amount, as a function of frequency). Model simulations which attempt to account for the above difference suggest that there must be a stage of sharpening between the physical variable governing two‐tone suppression (tentatively identified as velocity of the basilar membrane) and the physical variable governing neural excitation. An experiment that would unequivocally demonstrate the simultaneous existence of two representations of the stimulus with significantly different tuning properties in the cochlea is described. The future evolution of cochlear modelling, incorporating nonlinear two‐dimensional models, is discussed.

A laser color printer has been developed to depict continuous tone color images on a photographic color film or color paper with high resolution and fidelity. We have used three lasers, He-Cd (441.6 nm), Ar4 + (514.5 nm), and He-Ne (632.8 nm) for blue, green, and red exposures. We have employed a drum scanner for two dimensional scanning. The maximum resolution of our system is 40 c/mm (80 lines/mm) and the accuracy of density reproduction is within 1.0 when measured in color difference, where most observers can not distinguish the difference. The scanning artifacts and noise are diminished to a visually negligible level. The image quality of output images compares well to that of actual color photographs, and is suitable for photographic image simulations.

The effect of shadows and interreflection created by room obstructions is an important factor in the continuous tone representation of interiors. For indirect illumination, in most cases a uniform ambient light has been considered, even though the interreflection gives very complex effects with the shaded images.The proposed method for indirect lighting with shadows results in the following advanced points:1) The indirect illuminance caused by the surfaces of objects such as ceilings, floors, walls, desks, bookcases etc. gives added realism to images.2) The proposed method is suitable for every type of light source such as point sources, linear sources, and area sources.

Various types of permanent hardcopy images consisting of dots or raster lines can be output from the same scanner because it writes a fixed-pitch dot. The machine is easy to use and can stand alone or can be interfaced to other image processing equipment.

Conventional image quality metrics in photography evolved in the context of so called continuous tone images. In electronic imaging there is now an ever increasing need to develop metrics which apply to (output) images which are quantized, as from laser writers or digital halftone schemes. Fortunately the most robust of the conventional metrics are based on or compatible with the concept of the quantized nature of light (input), and extending these to the case where both input and output are by definition discrete is usually straightforward. A survey is given of these metrics, with examples from recent work on laser writer hardcopy.

A detailed discussion of an on -line Laser Beam Recorder /Processor utilizing transparentelectrophotography as well as its performance in regard to critical image processing par-ameters and their impact on sensitometry and image quality is presented. Good sensitometryand high image quality combined with near real time access has been demonstrated. Sensito-metric parameters such as D -max, D -min and gamma can be controlled during dynamic process-ing through electrical parameters.ObjectiveDemonstrate the viability of transparent electrophotography for continuous tone on -linelaser beam recording.IntroductionA description of an experimental Laser Beam Recorder (LBR) utilizing transparentelectrophotographic film will be presented in conjunction with data acquired with theinstrument. Also included is a detailed discussion of the system's performance with regardto the critical image processing parameters and their impact on sensitometry and imagequality. There will be 35mm slides showing the LBR and several of its components.The work discussed here has demonstrated that the TEP® process' is a viable candidatefor recording at high data rates with laser bean scanning systems. The quality of theimagery is equivalent to presently available silver halide films and there is promise ofmuch higher quality. The simplicity of the process and the attained image quality offermany potential advantages for on -line processing laser recording systems. Part of thiswork has been sponsored by the USAF, AFAL Wright -Patterson Air Force Base, Air ForceContract No. F- 33615 -76 -C -1312 -- Mr. Roland D. Dunker, Technical Monitor.The transparent electrophotographic process

The synthesis of continuous tone raster scan images has been the subject of considerable research effort over the past decade or so. Many algorithms have been developed during this period, and many significant advances have been made. However, very few images have been produced which require more than a moment's study to reveal their synthetic origins. This paper reviews the major issues of relevance to the goal of realism in synthetic images. The major achievements towards this goal are reviewed, and the main outstanding problems are identified.

Algorithms for bilevel display of continuous tone images should provide reproduction of edge detail and proper rendition of continuous tone regions with binary textures that adequately reproduce image gray scale without introducing additional structure into the image. Error diffusion algorithms have been shown to have the capability of generating visually appealing binary images, but existing schemes will sometimes generate undesirable textural artifacts. A new image binarization algorithm is developed based on a Markov random field texture model and an edge based constraint matrix. The resulting Markov random field error diffusion algorithm generates nondeterministic binary textures that overcome some of the problems associated with conventional binarization algorithms.© (1984) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The history of radiographic duplicating technology has at times been concerned with improving the extraction of information from radiographs. Recent work in diazotype radiographic duplicating film has resulted in a continuous tone direct positive film which is capable of visual enhancement of edge-sharpness and contrast. The convenience it affords of room light handling contributes to its value as an interpretive and diagnostic aid in conjunction with the original radiograph. Specific examples are discussed.© (1977) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Neuromagnetic responses to frequency modulation of a continuous tone were studied in nine subjects. The latencies of the transient responses increased and the amplitudes decreased with decreasing speed of modulation. The equivalent dipoles for modulation of a 1,000 Hz tone were slightly but statistically significantly anterior to the dipoles activated by modulation of a 500 Hz tone. The generation mechanisms of N100m are discussed.

An intermittent monaural tone may induce a decline in the loudness of a continuous tone presented to the same ear [Canevet et al., Br. J. Audiol. 17, 49-57 (1983)]. Two experiments studied the frequency selectivity of loudness adaptation induced in this manner. The method of successive magnitude estimations was used to measure the loudness of a monaural 84-s test tone before and after a single presentation of a 24-s inducer tone in the same ear. The first experiment shows that, for an inducing tone (500, 1000, or 3000 Hz) approximately 15 dB more intense than a test tone set to one of 21 different frequencies, adaptation is greatest when the two tones have the same frequency; with increasing difference between the test-tone and inducer frequencies, adaptation progressively declines. The second experiment measured frequency selectivity in the loudness reduction caused by a 1000-Hz inducer as a function of its level. As inducer level went from 75 to 95 dB (with test tone constant at 60 phons), selectivity passes progressively from the type seen in short-term or low-level fatigue (maximal for the 1000-Hz test tone) to a type seen in long-term or high-level fatigue (maximal for the 1000-Hz test tone) to a type seen in long-term or high-level fatigue (maximal at frequencies higher than that of the inducer or fatiguing tone). A common cochlear origin and a continuity between the mechanisms of ipsilaterally induced adaptation and high-level fatigue are suggested by the data.

A 500‐Hz tonal signal was masked by a continuous tone, both from the same oscillator. A two‐interval‐forced‐choice procedure was used to determine the level required for 80% correct. The masker level was 50 dB SPL, and the signal was always in phase with the masker. Signal durations from 20 msec to 2 sec were employed. The results showed a slope of approximately 3 dB per doubling over the entire range from 20 msec to 1 sec. Detection at 2 sec tended to be worse than at 1 sec. The slope of 3 dB per doubling is much steeper than has commonly been found with noise maskers, especially at the longer durations. Data from an electrical model are discussed.

Most models of hearing loss explicitly or implicitly assume that damage to the hair cells reduces the amount and distribution of input to the central auditory mechanisms according to the pattern of damage along the receptor surface. Thus, the basis for reduced psychophysical performance with hearing loss was initially sought in the pattern and distribution of cochlear damage and not in altered central mechanisms. It is now apparent that central anatomic changes follow the peripheral changes produced by acoustic trauma [1,2] or auditory deprivation in the young animal [3,4]. Central physiological differences between the normal-hearing and hearing-impaired animal have also been reported in a variety of preparations [5–9]. The argument is made herein that a contemporary model of hearing impairment not only must include impoverished transduction, but must recognize altered central processing as well.

Electronic color scanners have found wide acceptance in graphic arts and related fields forrecording of color separations. The accuracy and flexibility of electronic image processing exceedsphoto optical methods. Size changes, color correction and masking functions are accomplished electroni- cally. A recent addition (1974) to these functions is electronic dot generation by means of modulated laser beams. This provides the user with additional features, increased processing speed and hard dotgeneration independent of external parameters or material. This paper describes the basic configurationof the Chromagraph DC 300 and its electronic dot generation.The DC 300 is an electronic color scanner for the production of color and tone corrected continuoustone, contact screened and electronic screened separations for all printing processes.Color transparencies or flexible reflection copy up to size 16" x 20" can be scanned. A special masking control drum provides for the combination of picture elements from more than one original, insetlettering and insertion of tints and tones.Using digital storage techniques, the output reproduction range is from 10% to 3000% with regard tooriginal or part of the original being scanned.The output film size is 16" x 20 ". Positive or negative separations can be push button selected,right reading or wrong reading with respect to the original. Continuous tone separations can be recordedwith line resolutions from 350 to 1000 lines /inch. Using a set of 4 prepunched, preangled grey contactscreens, screened separations from 65 line to 300 line per inch can be produced.Using the electronic dot generation system and a laser beam as the exposing light source, screenedseparations from 85 lines to 200 lines per inch can be produced.One color or two colors can be exposed onto the 16" x 20" film in one pass of the exposing head,depending upon the size of the output picture. Scanning times vary according to the method of producingthe separations; i.e. continuous tone vs. contact screened vs. laser screened, but on average the laserscreening system is twice as fast as the other two recording methods.The normally used 150 line screen exposes at 15 seconds per inch across the axis of the drum.Therefore, it takes 4 minutes to expose the available 16" x 20" area. One to four separations can beexposed in this time period, depending on the image size.The DC 300 was initially a non -laser machine, the first delivery was in mid 1972. The laserelectronic screening system became available in late 1974.To date, there are over 280 DC300s installed in North America, about 35 of these are strictlycontinuous tone machines for the rotogravure industry. Of the balance about 250 are laser equipped.Many of those sold before the laser system had been available have now had the laser system fitted, itcan be bought as an inplant retrofit kit. Furthermore, at the present time, about 40 machines are onorder, all except one (a rotogravure machine) are equipped with the laser screening system.This indicates clearly the customer (end user) preference of laser screening over contact screens.The following Block Diagram (Fig. 1.1) shows the basic configuration of the DC 300 scanner.

Duplication of high-quality continuous-tone photography requires a capability to accept broad ranges of contrast and maximum density in the original negative. An electrophoto-graphic system using liquid toner and a final-imaging photoconductive film has been shown to meet these requirements. The system can be applied in continuous roll duplication of high-quality originals. A description is given of the special characteristics and control of the photoconductive film that make it applicable in this system, taking advantage of the property of persistent conductivity to augment conventional electrostatic image formation.© (1983) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Frequency glides from a continuous tone have been shown to produce activity from the human cortex that can be recorded as time-varying magnetic fields outside the scalp in the same way as simpler auditory stimuli such as clicks and tone bursts. Data analysis has been based on a model assuming an equivalent current dipole localized close to the skull surface. Recorded data have shown good agreement with such a model. Interhemispheric differences have been shown in the location of this dipole, as well as with regard to dipole moment and latencies of responses to contralateral stimulation. The location of the equivalent dipole for frequency glide stimulation is close to that previously reported for tone pulse stimulation. However, the results indicate that differences in location of the order of 10 mm may exist. Comparing previously reported electric responses to frequency glides indicates essentially qualitative agreement although some significant differences have also been found. This is interpreted as evidence that at least the major contributions to the two types of response are produced by the same generator in the temporal lobe of the human cortex.

In this paper we show that annular source and dynamic coherent phase contrast viewing systems are equivalent. Experimental results which demonstrate the equivalence by showing the bandwidth doubling are included. The additional noise reduction and the continuous tone capability of these systems is also shown experimentally.

In the graphic arts industry, a digital image is stored as four continuous tone files of Cyan, Magenta, Yellow, and Black (CMYK). These are the most common colors used in a 4-color ink printing process. Since a printing press cannot print "differential" amounts of ink at a given location, printers achieve fine tonal gradations by printing halftone dots of smoothly changing "areas". A screening computer's primary function is to convert these continuous tone pixel values into halftone dots. In general, the task of transforming continuous tone pixel values into halftone dots is computationally intensive. Furthermore, when using a high resolution output writer, screened halftone bitmapped images can easily exceed 100 Mbytes per separation, resulting in lengthy and unacceptable screening times. As a result, the sheer volume of data that must be manipulated in the screening process dictates the need for a high performance, special purpose screening engine, which does not degrade the performance of the target system. This paper first introduces the fundamental theory and concepts of electronic digital halftone screening. Second, a set of fundamental functional requirements for a digital screening computer are developed. Third, a parallel, pipelined screening computer design, which meets the developed functional requirements, is presented. Last, an illustration of digitally screened halftone dots is provided.

Continuous-tone images produced by mechanically scanned analog modulated laser beams are susceptible to image artifacts in the form of spatially periodic density variations due to machine errors in film transport velocity, raster scan-line placement, and scan-line intensity. The human eye is particularly sensitive to periodic patterns and, in ideal conditions, can detect peak-to-peak density variations as small as approximately 0.005 for spatial frequencies around 2-5 cycles/deg. The stringent requirements that this implies for the scanner hardware are derived. Particular attention is paid to the rotating polygon-type scanner, since this device currently provides the best combination of speed, image quality, and cost.

In the primary auditory cortex of cats anaesthetized with nitrous oxide, single neurones were examined with respect to their responses to tone bursts and linear modulations of the frequency of an on-going continuous tone. Using FM ramps of 2.0 kHz excursion and varying centre frequency, each of 39 neurones was examined for its preference for the direction of frequency change of a ramp whose centre frequency was varied in and around the neurone's response area. Direction preference was strictly associated with the slopes of the cell's spike count-versus-frequency function over the frequency range covered by the ramp. Preferences for upward- and downward-directed ramps were associated with the low- and high-frequency slopes of the spike count function, respectively. The strength of the cell's direction preference was associated with the relative steepness of the spike count function over the frequency range covered by the ramp. The timing of discharges elicited by the frequency modulations was found to be the sum of the cell's latent period for tone bursts plus the time after ramp onset that the stimulus frequency fell within the neurone's response area. The implications of these data for the processing of narrow and broad frequency-modulated ramps are discussed.

The detection of changes in sound intensity (ΔI) is one of the fundamental auditory capacities for which auditory systems have presumably been “designed” throughout evolution. Questions of the neural representations of sound intensity, and the ways these are processed by the brain are basic to an analysis of sensory coding. The psychophysical literature contains two major observations: (1) The ratio ΔI/I is approximately constant for noise signals within a wide range of I values (i.e., Weber’s law holds) (Miller 1947, Rodenburg 1972). (2) For tone signals, ΔI/I declines somewhat at larger I values (i.e., there is a “near miss” to Weber’s law) (Reisz 1928, McGill and Goldberg 1968, Jesteadt, Wier, and Green 1977, Steigel 1977).

Mead Imaging is commercializing Cycolor ® , a revolutionary photoimaging system which will have broad applications in color copying and reproduction, referred to as cylithography. Cycolor possesses the following characteristics: • panchromatic sensitivity • dry processing • high resolution • continuous tone • high color quality • low cost. The Cycolor system is a result of work carried out at Mead Corporation over the past several years on the microencapsulated process.

New opportunities are emerging in the graphic-arts pre-press market stimulated by the need for digitally created images. To meet this need, we have designed a cost-effective three-color digital printer using PLZT light valves. Transparent lead lanthanum zirconate titanate (PLZT) ceramic crystals when used as a linear modulator offer a number of significant benefits. The primary advantage is that the light valve is an efficient modulator of incoherent light providing a broad spectral output ranging from 400nm to well into the infrared region. In addition, light valves offer the advantages of being small, low cost, have a wide dynamic range (>1000 to 1), and can be used with simple optical designs. The characteristics of the PLZT material plays an important role in the performance of the light valve. A number of variables such as ceramic composition, electrode spacing, and ceramic thickness can be altered to affect its quadratic electrooptic behavior. Additionally, the modulator design requires a closed-loop servo to eliminate the errors caused by the device's remanent polarization and nonlinear behavior.

The tone scale or gradation of a continuous tone picture is the most important factor related to the quality of an image. We have developed special purpose analog and digital circuitry which enables the real-time (30 updates per second) computation of a tone scale transformation which is then applied to a digitized picture being displayed on a television monitor. In our system the tone scale transformations are controlled by knobs which are labelled in terms meaningful to photographic artisans, rather than requiring an operator to specify points on a transfer characteristic as is common with other systems. These knobs directly specify minimum and maximum densities, brightness, and shadow, highlight and overall contrast. These control parameters may be selectively enabled by the operator. After the appropriate aesthetic modifications have been achieved on the television display, the operator may initiate the transformation of the complete stored image prior to subsequent computer processing or hard copy output.© (1982) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The effects of fixed frequency tracing orders at 4000 cps upon thresholds in quiet, in noise and in recovery after noise exposure were determined on a Bekesy audiometer with 32 normal hearing adult subjects. The results showed that:1. In the pulsed/continuous tracing order in quiet the difference in threshold sensitivity was non-significant. Conversely, in the continuous/pulsed tracing order in quiet the pulsed trace threshold was significantly more acute.2. Order effects were present also in the noise tracings. Post-rest pulsed tones were more acute than pre-rest continuous tones. However, the converse was not true.3. Tracing order effects were operating in the recovery thresholds. Postrest pulsed recovery thresholds were more acute than pre-rest continuous recovery thresholds. Also, initial thresholds in quiet appeared to have a significant effect on subsequent recovery thresholds for continuous tone tracings. This finding did not obtain for pulskd tones.4. When initial thresholds in quiet were compared...

A group of subjects with sensory-neural noise-induced hearing loss was tested with a fixed-frequency Bekesy type audiometer. Responses were studied for signs of abnormal auditory adaptation and increased differential sensitivity. Adaptation was defined as a poorer threshold response to a continuous tone than to an interrupted tone. Increased differential sensitivity was defined as a narrower envelope of responses to the continuous tone than to the interrupted tone. It was found that all subjects showed both of these effects to some degree. It is suggested that adaptation increases differential sensitivity by raising the threshold. It would seem impossible to measure a sensitivity differential unaffected by adaptation in this category of hearing loss. It is concluded that a fixed-frequency Bekesy technique may be the most fruitful approach to recruitment testing since both effects may be measured concurrently with this procedure.

It is the purpose of this experiment to observe recovery of abnormal auditory adaptation by means of Bekesy fixed frequency audiometry and reverse TTD test. After the tested ear showed maximum elevation of auditory threshold in usual TTD tra-cing by nsing a continuous pure tone, the recovery process just from the highly adapted state of the ear was traced by these two methods.Test signals used were the continuous, the amplitude-modulated, and the interrupted pure tones. The results were as follows :1) Bekesy tracing for a continuous pure tone showed no recovery of auditory threshold from the temporary hearing loss in TTD test and smal-ler amplitude than the nonadapted state of the test-ear, whereas that for an interrupted pure tone showed complete recovery from the hearing loss and normal amplitude similar to the nonadapted state.2) As the ampitude modulation of the test tones was increased, recovery curves of Bekesy and reverse TTD tracings were changed in thre-sholds and amplitudes from those of the more adapted state of the test-ear for a continuous tone to those of the less adapted state for an interru-pted tones

A comparison of threshold variation among patients with sensorineural hearing loss and accompanying tinnitus in relation to plused and continuous tone threshold determination was reported. The results indicated that both types of signals obtained comparable threshold levels at all audiometric frequencies tested, and did not vary by more than 1.6 dB. The greatest variation in threshold occurred at those frequencies which corresponds to the reported tinnitus. The latter was observed for 5 patients and did not exceed 5 dB. All threshold variations were within the acceptable criterion of ±5 dB. The majority of patients reported high-pitched tinnitus, and most frequently matched their tinnitus to 3 000 Hz. Over two-thirds of both normal and tinnitus subjects preferred to listen to pulsed tones as opposed to continuous tones during threshold determination. The data obtained from this study did not confirm the assumption that significantly lower threshold are obtained with pulsed tones among patients with tinnit...

Seven male and seven female subjects were exposed to a monaurally presented 1000-Hz continuous tone at 110 dB SPL for three minutes. During the exposure pulsed wide-band noise (one second on / one second off) was presented to the contralateral ear. Six noise levels (70, 80, 90, 100, 110, and 115 dB SPL) were used. In addition, a control condition consisting of the absence of contralateral stimulation was used. Pre- and postexposure thresholds were tracked with a Bekesy type procedure for a stimulus one-half octave above the exposure frequency. TTS was greatest for the control condition (no contralateral noise) and became progressively less as the SPL of contralateral noise was increased from 70 to 115 dB. The inverse relation between magnitude of TTS and the level of contralateral noise was attributed to stapedius muscle activity. Hence, the data provided psychophysical support for the contention that the stapedius muscle reflex is graded in response to the level of acoustic stimulation. The data also indicated an absence of significant differences in TTS magnitudes between males and females.

Two studies were performed to determine the parameters affecting the sensitivity and variability of Bekesy thresholds. The first study was concerned with the effects of varying period, duty cycle, and frequency on threshold measurements obtained using pulsed tones and was done to derive an “optimal” pulsed tone. The second study compared thresholds taken using the optimized pulsed tone to those obtained with continuous tones. The effects of varying attenuation rate with both types of presentation were also investigated. Pulsed tones were found to yield superior threshold measurements both in terms of greater sensitivity and less intratest variability. Also, continuous tone thresholds were found to be susceptible to changes in attenuation rate whereas pulsed tone thresholds were not.

For the purposes of description and study, the electrophotographic process may be divided conveniently into six parts: (1) the electrophotographic plate, (2) sensitization of the plate, (3) exposure of the sensitized plate, (4) development of the exposed plate to produce a powder image, (5) transfer of this image from the plate to a final support, and (6) fixing the transferred image to make the final print.

Six subjects with abnormal adaptation tracked their thresholds on a Bekesy audiometer for a fixed frequency interrupted pure tone stimulus presented in conjunction with a continuous tone of the same frequency at levels 20, 10 and 5 dB below that of the interrupted tone. The presence of the continuous tone below the threshold for the interrupted tone produced abnormal adaptation in four of the subjects, and narrowing of the excursion width of the tracings in three of the subjects. Effects of the below-threshold continuous tone were found in subjects with cochlear lesions, as well as in subjects with retro-cochlear lesions. It is concluded that continuous stimulation does not have to be at threshold to produce abnormal adaptation in susceptible individuals.

IT is well known that a sensation of continuous tone may be produced by presenting to the ear regularly repeated trains of sinusoidal waves, although each train may consist of only a few oscillations followed by a relatively long ‘blank’ period1. I have observed that a sensation of tone may arise by the presentation of trains of very short pulses, each pulse of duration of 0.20 m.sec., and each train consisting of two such pulses only. The pulse duration quoted is that measured on a cathode ray oscilloscope across the output of the amplifier, no suitable instrument being available to monitor the air pressure wave-form as produced by the loudspeaker. The pulses were derived from an electronic stimulator, and were locked to the time-base at predetermined times, each being independently adjustable. Hence, for each time-base two pulses were obtained, the separation of which in time could be varied from zero (coincidence) to 10 m.sec. The time-base repetition-rate could be varied from 10 to 100 per sec. Within this range, at any given rate of repetition, progressive separation of the pulses gave rise to a sensation of falling pitch, and approximation caused a rising pitch. At a separation of 1 m.sec., the sensation was that of a 1,000-cycle per sec. tone, as matched against a known frequency source; at a separation of 2 m.sec. the tone was 500 cycles per sec., at 4 m.sec. 250 cycles per sec., and so on. Since the tone sensation dependent on the pulse separation was heard against a background due to the frequency of repetition of each pulse (the time-base repetition-rate), only those derived tones of frequency considerably higher than the frequency of repetition could readily be detected and matched against the standard frequency source.

Information across different senses can affect our behavior in both positive and negative ways. Stimuli aligned with a target stimulus can lead to improved behavioral performances, while competing, transient stimuli often negatively affect our task performance. But what about subtle changes in task-irrelevant multisensory stimuli? Within this experiment we tested the effect of the alignment of subtle auditory and visual distractor stimuli on the performance of detection and discrimination tasks respectively. Participants performed either a detection or a discrimination task on a centrally presented Gabor patch, while being simultaneously subjected to a random dot kinematogram, which alternated its color from green to red with a frequency of 7.5 Hz and a continuous tone, which was either a frequency modulated pure tone for the audiovisual congruent and incongruent conditions or white noise for the visual control condition. While the modulation frequency of the pure tone initially differed from the modulation frequency of the random dot kinematogram, the modulation frequencies of both stimuli could align after a variable delay, and we measured accuracy and reaction times around the possible alignment time. We found increases in accuracy for the audiovisual congruent condition suggesting subtle alignments of multisensory background stimuli can increase performance on the current task.

In this paper, we propose a novel rate allocation method for compound image coding using Quality-biased Rate-Distortion Optimization (QRDO) technique to enhance visual quality. The compound image is divided into 16 /spl times/ 16 blocks, which are further classified into four types: smooth, text/graphics, continuous tone and hybrid blocks. Four carefully designed coding approaches according to different statistical features are introduced to compress them, and rate-distortion tradeoff with QRDO technique is considered to decide which approach should be used for each block. The quality of "text" regions is specially emphasized during this process by weighting blocks according to their types, which is verified by experimental results.

It is shown that, when ordered dither is employed, the constrained-average algorithm presented in the above paper is equivalent to ordered-dither coding of a picture which has been subjected to a well-known method of edge enhancement. The magnitude of the parameterγ controls the degree of edge enhancement and the dither signal amplitude controls the picture contrast.

As is well known, raising of the threshold of hearing is caused by exposure to a continuous tone. The magnitude of this effect is a function of the frequency, duration and intensity of the tone. In general it is small, with intensities which do not exceed 90–100 db. above normal threshold in the middle frequency range.

The effectiveness of pulsed and continuous masking was investigated as a function of frequency, with the masker presented at equal sound‐pressure levels and then at equal effective‐masking levels. Thresholds at 250, 1000, and 4000 cps were recorded by 10 subjects via a graphic attenuator while a wide‐band random noise was delivered either to the test ear (monotic) or the contralateral ear (dichotic). Three methods of presentation were used: (1) pulsed tone and pulsed noise, simultaneous; (2) pulsed tone and continuous noise; and (3) continuous tone and continuous noise. In both the monotic and dichotic conditions, the effectiveness of the pulsed masker, whether presented at equal sound‐pressure levels or at effective levels, increased with signal frequency. The threshold shifts in the monotic and dichotic conditions also increased with frequency but the changes were slightly less than for the pulsed‐pulsed condition. When noise was present, changes in the variability around threshold as estimated by frequency of excursions over time were observed under certain conditions. This finding was related to the theoretical interpretation of the results. [This work was supported by the National Institutes of Health, U. S. Department of Health, Education, and Welfare.]

A mechanical violin bower, giving a constant and continuous tone as required for recording by a crystal analyzer and sound level recorder, was made and used for measuring the “response” from violins. The report on response measurements was given at the Pittsburgh meeting. This report deals only with the mechanical bower. The bow, as now made, is composed of fine silk strands, loosely spun, and treated with a quick hardening lacquer. This hair‐like thread is wound around two grooved pulleys many times, and the two ends are fastened together to form one continuous thread. Fine‐toothed guides placed in front of the pulleys keep each strand in its proper place, and form a flat belt which performs like a regular violin bow. By a proper mounting of this belt on a frame, and by having a small motor to run it, the desired results are obtained. The frame holds a violin in the same manner as held by a violinist. A spring attached to the frame and violin support hold the pressure of the bow on the string at any desired constant value. The speed of the bow is regulated by an adjustable friction gear. The silk thread bow produces tones free from scratching noises, and comparable to those produced by a horse‐hair bow.

Four albino rats were trained to depress a lever on a DRL schedule. Reinforcement was delivered 10 sec. after a correct response. A tone immediately followed a correct response. The Ss learned the DRL performance by reducing initially long IRTs rather than increasing initially short IRTs as is usually the case when reinforcement is not delayed.

We consider the binary representation of hexagonally sampled continuous-tone images. The method of error diffusion is extended for the hexagonal lattice. Aliasing artifacts as well as the spatial patterns generated with this method are compared with those obtained in the binarization of rectangularly sampled images. The nonideal printing process is analyzed for this lattice structure, and the binarization process is modified so as to suppress dot overlap and minimize tone degradations. On a nonideal printer it is shown that binarization in a hexagonal lattice is more robust than in a rectangular one in tone preservation.

Bekesy fixed‐frequency thresholds for pulsed and continuous tones were compared for different starting intensities and attenuation rates (attenuation steps) in subjects with normal hearing. Starting intensities were 38, 58, 78, and 98 dB SPL. Attenuation rates were 1, 2, 4, and 8 dB/s with attenuation steps in 0.25, 0.5, 1.0, and 2.0 dB/s, respectively. For pulsed tones, the threshold was not significantly affected by varying starting intensities or attenuation rates (attenuation steps). Reducing the attenuation rate (attenuation step) produced an elevation of continuous tone thresholds for a given suprathreshold starting intensity. Increase in the suprathreshold starting intensity produced an elevation of continuous tone thresholds for a given attenuation rate (attenuation step). The slower the attenuation rate (the slower the attenuation step) and the higher the suprathreshold starting intensity, the higher the threshold. This is considered a manifestation of normal adaptation. Present findings were compared and discussed with our previous studies for the threshold differences measured by different attenuation rates with a fixed attenuation step in 0.2 dB starting at the same suprathreshold intensities.

The algorithm developed by Kiang and Moxon [J. Acoust. Soc. Am. 55, 620–630 (1974)] to track the isorate response of a single fiber with respect to frequency (tuning curve) was modified to track the lower threshold boundary of two‐tone rate suppression (TTRS). In this study automated tuning curves were first determined, after which a continuous tone at the fiber's characteristic frequency (CF) was placed 10 to 15 dB above threshold. Results indicate that suppression boundaries, especially those below CF, are often remarkably similar in absolute threshold for fiber CFs between about 0.6 to 12.0 kHz. Further, the absolute level of the suppression boundary is largely independent of that of the tuning curve and its tail. For example, fibers of similar CFs can have tail thresholds differing by as much as 30 dB yet have essentially the same TTRS contours. These data suggest that the tuning curve is a locally determined phenomenon along the cochlear duct, whereas TTRS is determined more globally and is to a larg...

Adaptation to a stimulus environment often implies suppression of the redundant features in favor of stimuli carrying more information. Study of auditory adaptation of a continuing (redundant) stimulus, also requires consideration of the less redundant “comparison” stimulus. A magnitude estimation loudness adaptation study (1 kHz, 60 dB) designed to parallel the steps of the SDLB technique, yielded the following: (a) no loudness adaptation occurred during the pre‐test baseline when binaural simultaneously intermittent stimuli were presented, (b) immediately afterward, 7 min. of continuous redundant monaural stimulation yielded negatively accelerated adaptation, (c) finally, restoration of intermittent stimulation in the contralateral ear, resulted in apparent binurally “induced” adaptation of the continuous tone, but not of the less redundant intermittent tone. Previously, monaural heterophonic balances (Weiler and Friedman, 1973, etc.) resulted in the decline of the continuous (redundant) tone in the presence of an intermittent comparison tone. In summary, adaptation occurs in the more redundant stimulus when the two are competitive, similar, and in the same frame of reference.

Botte, Canevet, and Scharf (1982) induced Magnitude Estimated (M.E.) loudness adaptation of a continuous tone by means of a simultaneous intermittent contralateral tone. The present study investigated the need for simultaneous contralateral stimulation to induce M.E. adaptation. During the pre‐test, simultaneous intermittent binaural stimuli were presented at 60 dB SPL, 1 kHz. During the adapting (middle) phase, the tone was presented monaurally and continuously for 7 min. This stimulus continued into the post‐test when the contralateral intermittent tone was re‐introduced. No change in loudness was reported during the pre‐test. A significant cumulative decline in loudness was reported for the monaural 7‐min adapting phase. Re‐introduction of the binaural contralateral tone resulted in additional adaptation. Simultaneous presentation of the contralateral tone was not necessary to observe loudness adaptation.

There are many ways of displaying a video signal derived from graphical material. People in the graphic arts business have been wrestling with the same sorts of problems for more than 100 years; this article surveys what they have done, in the hope that some useful technology transfer may occur.