FM Tape Recorder Research Articles

A Psychophysiology of Developmental Disabilities: A Personal and Historical Perspective

In the early 1970s, as a curious young assistant professor in the Department of Psychology at the University of Illinois at Urbana–Champaign, my colleagues asked me to apply heart rate monitoring to study the intellectually impaired. Although many of my colleagues were dedicated to the study of developmental disabilities, this was a new area for me. The University of Illinois had a physical center and an administrative structure to expand the behavioral sciences into the study of typically and atypically developing children, and the Children’s Research Center was the epicenter of this research interest. The Center was headed by Bob Sprague and included several researchers—Steve Asher, Ann Brown, Joe Campione, Mark Gold, and Keith and Marcia Scott—who conducted research on mentally challenged children. The research conducted at the Center was well funded and was a high priority for both the State of Illinois and the National Institutes of Health. In retrospect, this was a special time and special place for the study of normal and atypical development. I recall one meeting in which approximately 35 faculty members across several departments and colleges on the University of Illinois at Urbana–Champaign campus self-identified as developmental psychologists. It was an optimistic time, and there were expectations that physiological monitoring would provide a portal to better understand individuals with limited language skills and cognitive resources. In the 1970s, the State of Illinois was committed to improving the quality of children with developmental disabilities. There were statefunded centers for treatment and research and state-funded research grants. For example, in Chicago, the state funded an intramural research program in a facility on the University of Illinois Medical School campus known as the Illinois State Pediatric Institute. This facility was located adjacent to another state-funded research program known as the Illinois State Psychiatric Institute. These large buildings housed basic and clinical researchers focused on understanding and improving the lives of individuals with developmental disabilities and mental health disorders. During the mid-1970s, in this background of interest and enthusiasm for research to study atypical development, I received a grant from the State of Illinois, Department of Mental Health and Developmental Disabilities to study heart rate patterns in ‘‘retarded and nonretarded’’ adolescents. To conduct this research, I borrowed from my colleague, Bob Sprague, a van that had been modified into a two-room research laboratory. With a graduate student, Mary Humphrey, and the help of a couple of talented undergraduates, we drove the van to local schools to collect the data. To do a simple study, we packed about 200 pounds of equipment into the van, including a Beckman Dynograph, an FM tape recorder, a 6-foot equipment rack containing relays programmed to display the stimulus via a slide projector and to record the responses through button presses, and a TV monitor and camera to reduce fear and uncertainty for the participants by enabling them to observe each other participating. The study resulted in a publication in the American Journal of Mental Deficiency (Porges & Humphrey, 1977), which was the former name of the American Journal on Intellectual and Developmental Disabilities. What has changed in the decades since my paper with Mary and this issue of the Journal on Intellectual and Developmental Disabilities? From my perspective, there have been three major interrelated changes. First, in 1977, it would have been virtually impossible to find sufficient intellectual material on heart rate monitoring in special populations to fill an issue of any journal. In the mid-1970s, only a few researchers studied autonomic function in special populations. Most notable was Rathe Karrer. Rathe was a psychoAMERICAN JOURNAL ON INTELLECTUAL AND DEVELOPMENTAL DISABILITIES

Ambulatory Arrhythmia Monitoring

Remote cardiac telemetry was developed to allow home ECG monitoring of patients with suspected cardiac arrhythmias. It was first introduced by the American biophysicist Norman J. Holter (1914–1983) in the 1940s. The original Holter monitor was a 75-lb backpack with a reel-to-reel FM tape recorder, analog patient interface electronics, and large batteries.1,2 It could record a single ECG lead for several hours and provided the first opportunity to record and analyze ambulatory ECG data outside a standard hospital or outpatient care setting. The clinical need to monitor outpatients has resulted in advances in technology that now allow us to monitor heart rhythms remotely through a wide variety of devices, including ambulatory external monitors, implantable event recorders, pacemakers, and cardioverter-defibrillators. The rapid expansion of ambulatory monitoring technologies affords the clinician the obvious diagnostic advantage of more comprehensive and real-time data. It also presents the challenge of creating systems to handle and pay for this increased information and the potential liability associated with a continuous data stream. This review focuses on the available technology and factors that guide the choice of monitor. Traditionally, ambulatory monitoring has been used to determine the cause of palpitations and syncope and, to a lesser degree, to identify ventricular ectopy or nonsustained ventricular tachycardia in patients at potential risk for sudden cardiac death.3 Atrial fibrillation (AF) has become an increasingly important indication for ambulatory monitoring, predominantly as a tool to monitor the efficacy and safety of pharmacological and nonpharmacological therapies.4,5 It is also used to identify asymptomatic AF as a potential source of cryptogenic stroke.6,7 Several devices are currently available to remotely assess cardiac rhythm abnormalities in ambulatory patients (Table 1). Devices can record cardiac rhythm continuously or intermittently and can be worn externally or implanted subcutaneously. …

Whole-body vibration of tractor drivers during harrowing.

The seat vibration of nine tractors was investigated while drivers harrowed fields in eastern Finland. The vibration acceleration of the tractor driver's seat was measured simultaneously along three mutually perpendicular axes. The triaxial seat-accelerometer was used for the measurements. The vibration signals were amplified with charge amplifiers and recorded with an FM tape recorder. The samples were analyzed with a real-time analyzer. In all cases, the average vibration of the seat exceeded the 8-hour "fatigue-decreased proficiency boundary" specified in the international standard ISO 2631/1. The instantaneous accelerations of the most harmful one-third octave band of vibration were sometimes two- to threefold compared with the average.

Whole-Body Vibration of Tractor Drivers During Harrowing

The seat vibration of nine tractors was investigated while drivers harrowed fields in eastern Finland. The vibration acceleration of the tractor driver's seat was measured simultaneously along three mutually perpendicular axes. The triaxial seat-accelerometer was used for the measurements. The vibration signals were amplified with charge amplifiers and recorded with an FM tape recorder. The samples were analyzed with a real-time analyzer. In all cases, the average vibration of the seat exceeded the 8-hour “fatigue-decreased proficiency boundary” specified in the international standard ISO 2631/1. The instantaneous accelerations of the most harmful one-third octave band of vibration were sometimes two- to threefold compared with the average.

Application of spectral analysis techniques to cavitation in centrifugal pumps

ABSTRACT An experimental investigation has been performed to study the inception of cavitation and the effect of entrained air on cavitation in a double suction centrifugal pump. Experiments have been organized to cover off-design flow rates and reduced suction pressures independently so that has been possible to study both the effect of flow rate and suction pressure. Air of known amounts has been entrained from the suction pipe to investigate its effect on the intensity of cavitation and the performance of the pump. Pressure transducers and a FM tape recorder have been used to record the pressure signals acquired from three locations on the set-up. Consequently the data has been digitized and processed by spectral analysis techniques. The power spectra and the RMS values of the pressure signals have been investigated to reveal the inception and extend of cavitation as well as the effect of entrained air. As a result of the study carried out, it has been possible to conclude that spectral analysis techniques are useful tools for the detection of the inception and extend of cavitation and that although having some cushioning effect at the suction side of the pump air entrainment is not an effective method in reducing cavitation damage.

The rise and fall of the soft palate: The Velotrace

The Velotrace is a mechanical device that makes possible the collection of analog data on velar position [S. Horiguchi and F. Bell-Berti, Clin. Pal. J. 24, 104–111 (1987)]. The device consists of two levers connected through a push rod, carried on a support rod. The Velotrace is positioned with the support rod resting on the floor of the nasal cavity, with one lever resting on the nasal surface of the velum. When this internal lever is deflected upward, the second (or external) lever is deflected toward the speaker; i.e., changes in the position of the lever resting on the velum are directly reflected in the changes in position of the external lever. The position of an LED fixed to the end of the external lever is monitored with an optoelectric camera, and recorded with an FM tape recorder. [Supported by NIDCD Grant No. DC-00121 to the Haskins Labs.]

An On-Water Analysis System for Quantifying Stroke Force Characteristics during Kayak Events

A system was developed to quantify the on-water forces, impulse, and power generated by a kayak paddlet. The system is lightweight (<1 kg), portable (i.e., it can be used in single [Kl], double [K2], and fours [K4] boats), and does not affect the integrity of either the kayak paddle or the boat. Changes in the strain on the kayak paddle were measured by force transducers attached to the shaft of the paddle, and these signals were then recorded on an FM tape recorder located in the boat. The data were then analyzed by the Kayak Data Acquisition and Analysis System software which graphically presented the paddlers' force time curve as well as a printed tabular report on the paddlers' average force, impulse, work, power, and the instantaneous boat velocity.

Influences of Alprazolam on EMG in maximal voluntary efforts

A randomized controlled double-blind study was conducted to investigate the influences of different doses of Alprazolam (a benzodiazepine; 0.5, 1.5 and 3.0 mg) on the electromyogrophic activity (EMG) during standardized movement controlled maximal efforts. Nineteen healthy male subjects were tested 90 and 360 minutes after administration of the drug. Electromyography of the M. vastus medialis was measured during different exercise tests on an isokinetic dynamometer. The signals (both EMG and dynamometer output) were registrated by means of active surface electrodes (gain: 10: CMRR: 90 dB), amplified by means of differential amplifiers (gain: 300; CMRR: 85 dB); recorded on an FMtape recorder, low-pass filtered (second-order Butterworth) at 500 Hz. analog-to-digital converted and sampled at 2000 Ht. It was found that moderate to high doses of Alprazolam (1.5 and 3.0 mg) significantly (~4.05) reduced both integrated EMG and maximal EMG amplitude, and that 360 minutes after administration. only the high dose demonstrated significant decrease of the EMG signal. It is suggested that the observed relaxating effects of the drug may be due to the enhancement of gamma-aminobutyric acid (GABA) activity not only in the central nervous system, but also in peripheral receptor sites.

Continuous changes in electroencephalographic topograms and auditory reaction time during simulated 21 ATA (atmospheres absolute) heliox saturation dives.

The present study was designed to investigate EEG changes during two simulated 21 ATA hyperbaric heliox saturation dives. Four professional male divers were attached to 13 electrodes over the scalp and compressed to 21 ATA by helium. Throughout the dives, EEGs were measured and stored on a magnetic FM tape recorder to calculate electroencephalographic topograms. Three patterns of slow wave increase were clearly distinguished by the electroencephalographic topogram during compression. The first pattern was caused by trains or bursts of theta waves which spread from the frontal region to the central region of the scalp. This pattern occurred at comparatively shallow depth and showed the slowest recovery during the bottom stage among three patterns. The second pattern found in two divers was caused by frontal midline theta bursts, which showed maximum activity at F2. The frontal midline theta bursts were augmented by a reaction time task. The third pattern was caused by vertex sharp waves which indicated a transition from sleep stage 1 to sleep stage 2. Neurophysiological meanings of these EEG patterns as well as the relationship between EEG changes and other indices were discussed.

Digitizing and signal averaging of left ventricular pressure signals using a dedicated radionuclide imaging system.

A method for obtaining left ventricular (LV) volume curves, synchronized with average LV pressure (LVP) curves for calculation of LV contractility, is described. Multiple gated blood pool imaging was performed to calculate average LV volume curves. Simultaneously with this acquisition, LVPs and aortic pressures were measured by indwelling catheters and recorded on an FM tape recorder. These signals were fed to the computer as image information and averaged and processed by the software developed for this purpose. Pressure resolution of the calibrated images was 4 mmHg/pixel when provision was made for a maximum pressure of 200 mmHg. A good correlation (r = 0.99) was obtained between the calculated peak LVPs and mean peak LVPs read from the chart recorder. The regression equation was: digitized peak LVP = 1.04 x chart recording--5.11 mmHg and the standard error of the estimate was 2.9 mmHg. Similar results were obtained with the aortic pressure (AP) measurements (digitized AP = 0.94 x chart recording + 6.37 mmHg, the standard error of the estimate was 3.8 mmHg). The digitized data also allowed the construction of pressure-volume loops for interpretation of ventricular contractility.

Role of Gloves in Reducing Vibration: An Analysis for Pneumatic Chipping Hammer

The effects of vibration isolating gloves in reducing the vibration transmitted to the operator chipping castings were investigated. The actual chipping technique was simulated at the University of Iowa Department of Biomedical Engineering. The resulting accelerations measured during the chipping process were recorded on a four channel FM tape recorder through a set of accelerometers mounted on the back of the operator's hand used for holding/guiding the chisel. The data were digitized with a PDP 11/34 computer, and third octave band rms acceleration levels were obtained. The results indicated that the use of vibration isolating gloves reduced the vibration on the hand holding the chisel significantly in comparison to the bare hand. The average reductions achieved for the leather, Poron padded and Sorbothane padded gloves were 23.5%, 24.2% and 45.5%, respectively. Operators should be encouraged to wear vibration isolating gloves during the chipping process.

Low-Frequency requirements for recording ischemic st-segment abnormalities in coronary artery disease

The objective of this investigation was to determine whether extended low-frequency response is required to record ischemic ST-segment abnormalities in humans. Bipolar electrocardiograms (ECGs) were recorded in 5 men with coronary artery disease using a high-fidelity instrumentation amplifier and FM tape recorder before, during and after erect bicycle exercise. In all patients, ischemic ST-segment abnormalities developed during exercise; 3 patients had angina and 2 remained asymptomatic throughout the test. Using a fast-Fourier transform (FFT) and a variable digitizing rate into a 1,024-point input array, FFT spectra were computed with low-frequency content extending to either 0.20, 0.98 or 1.95 Hz for both a rest and exercise ECG. From these spectra, ECGs were resynthesized using the inverse FFT and compared with the original records. Visual inspection of the original and resynthesized ECGs revealed no obvious differences when lowfrequency content extended to 0.20, 0.98 or 1.95 Hz. Numerical comparisons were made by calculating the coefficient of determination (R 2) between the original and resynthesized ECGs. The R 2 (mean ± standard deviation) for these comparisons was 0.998 ± 0.001. It is concluded that the amplituderesponse characteristics of electrocardiographic recording equipment do not require extended low-frequency range (such as that found in FM systems) to accurately reproduce ischemic ST-segment abnormalities in humans.

Recording electrophysiological data on video tape: a superior and less costly alternative to conventional tape recorders

Electrical potentials recorded extracellularly from the sinus gland of the isopod, Oniscus asellus, were stored on video tape with the aid of a digital-audio (DA) processor and a video cassette recorder (VCR). The DA processor transforms the analog signal to digital pulses of equal amplitude and converts these pulses into a television signal for recording on video tape. In playback, the DA processor reconverts the pulses to an analog signal with negligible distortion. When viewed on the oscilloscope screen, electrical potentials reproduced by this method were indistinguishable from electrical potentials recorded ‘live’ from the sinus gland. However, electrical potentials recorded from the same sinus gland and reproduced by a conventional FM tape recorder were easily differentiated from the ‘live’ recording. The special effects inherent in the VCR (e.g. stop action, frame advance) also permitted detailed analysis of spontaneously occurring electrical potentials. Special effects were not possible with the FM tape recorder. The price, ease of operation and ability to produce extremely high quality recordings, makes the DA processor and VCR an exceptional system for storing electrophysiological data.

Mandibular position during children's defective /s/ productions

Mandibular displacement during /s/ production was monitored via a mercury strain gauge which was taped to the face of two normally articulating and six /s/-misarticulating children. Simultaneous audio and jaw displacement visicorder traces were produced from an FM-tape recording of each experimental session, and were subsequently analyzed. Results indicated that various /s/-misarticulating subgroups exhibit different mandibular positions during /s/- production, and phonetic contextual effects upon mandibular position also vary by articulatory type.

Recording system of infant oral response during regular feeding session

The sucking response is often used as a dependent variable in the study of infant behavior. Nevertheless, few attempts have been made to systematically investigate sucking within the context in which this response gets its original significance and adaptive function: nutrition. This might come partially from a lack of technical devices to make this kind of investigation feasible, without interfering with the bonding atmosphere that usually takes place between baby and caretaker during feeding sessions. A system has been designed to record the oral response of the infant during bottle-feeding. The system consists of a portable and otherwise convenient device mounted on a standard bottle that allows study of this type of response within the familiar environment of the bottle-fed baby, avoiding the usual laboratory constraints (Figure 1). The device is constructed as follows: Four strain gauges are connected to form a Wheatstone bridge and are glued on both sides of a rubber restraint which is tightened around the circular base of the bottle’s rubber nipple (Figure 2A). The rubber restraint is made of a normal rubber nipple that has been truncated at 10 mm from its base. The connecting order of the strain gauges is indicated in Figure 2B. Figure 2C shows the assembly of the device on a regular bottle. When no pressure is applied upon the nipple, the signal output of the resistance bridge has a null value, thus changing when a positive pressure is applied commensurate with the amount applied. The resulting signal output is amplified, and can be recorded on an FM tape recorder or can drive a graphic chart display. Two output signals can be recorded via the amplifier: (a) the AC conzponent (Figure 3A), which corresponds to the signal one can obtain by using

Acoustic Ranging Technique for Assessing Low-Frequency Acoustic Noise from Wind Turbines

An acoustic source ranging procedure is obviously a research tool and would not normally be attempted by an individual wind turbine owner. The minimum equipment necessary for the analysis includes three microphone systems preferably with very low-frequency response, an FFT dual-channel signal analyzer with hard copy or data output capability, and the necessary cabling. There is no requirement to record the acoustic data although it is certainly easier to post-process the data when all three microphone pairings can be analyzed from the same time record. If this is done, a suitable FM tape recorder with at least three tracks is required. Assessment of the degree of concentration of source region within a swept area is necessarily somewhat subjective. The time signal itself from one microphone should also be examined for periodic impulsiveness which would indicate a localization of source region. This can be analyzed in parallel with blade position (abiding acoustic transport delays) to corroborate a source ranging location.

An inverse filtering study of Burmese creaky voice

A systematic study of the glottal characteristics of creaky voice in a language which uses it for linguistic contrast has not yet been done. In Burmese, syllables can contrast plain and creaky phonation. The characteristics of these phonation types were studied using inverse filtering [R. L. Miller, J. Acoust. Soc. Am. 31, 667–677 (1959); G. Fant, Q. Prog. Status Rep. Speech Transmission Lab. No. 1, 85–107 (1979)]. A Burmese speaker was recorded in a sound‐treated booth using a high‐quality condenser microphone and an FM tape recorder. The recording was analyzed through an analog multi‐formant inverse filter. An Oscillomink was used to graph (1) the speech wave, (2) the output of the inverse filter (representing the differentiated glottal flow), and (3) the inverse filter output integrated to represent glottal flow. The differences between creaky and normal phonation can be described in terms of peak flow, the asymmetry between the rate of rise and fall of flow in each glottal pulse, as well as F0. [Work ...

A compact, microprocessor-based ECG ST-segment analyzer for the operating room.

We describe a microprocessor-based device for analyzing ST-segment changes of the electrocardiogram in the operating room during general anesthesia. The device identifies significant components of the ECG waveform, detects arrhythmias, and performs ST-segment measurements. Measured values of heart rate, QRS duration, R-wave magnitude, and ST-segment level, slope, area, and index are selectively displayed on a front-panel numeric display and can be recorded in analog form with an FM tape recorder. Provided are details of the battery-operated hardware, the ST-analysis software, and the results of 60 h of clinical trials. Possible uses are proposed for trend analysis during anesthesia.

An Electrophysiological Voltage to Frequency-Frequency to Voltage Fm Converter and Tape Recording System1

A relatively inexpensive high performance FM tape system for bioelectrical recording was developed utilizing voltage to frequency-frequency to voltage converters as intermediaries between an AM tape recorder and an oscilloscope. Frequency response is within 3 decibels from dc to 500 Hz with a rise time of ca. 1 msec with a conversion linearity of 1%.

The accuracy of ultrasonic fetal cardiography.

The present work investigated the accuracy of ultrasound cardiography (uFCG) in registering the fetal heart rate variability. Five patients in early labour were studied. Two cardiotocographs (HP 8030A) were simultaneously recording uFCG and direct fetal electrocardiography (dFECG). The information was stored in an analogue FM tape recorder for further data processing. The number of beats registered by the two methods were counted, and the time intervals between the beats were calculated. The short term variability (STV) and the long term variability (LTV) were investigated according to the definitions of DE HAAN [3]. To get an acceptable correlation coefficient in STV of 0.78, a difference as high as 5 beats per minute (bpm) between the two registrations had to be allowed. For LTV, a correlation coefficient of 0.70 was reached at a difference of 2 bpm. The results of the study show that the uFCG can hardly be used in interpretation of the STV. As the visual examination of the cardiotocograms reflects the LTV rather than the STV [7, 9], the uFCG can be used for interpretation of LTV provided that "jitter" is absent on the tracing.