Dip Type Research Articles

A Study of Hearing Loss of Chain Saw Workers

Otolaryngological and audiological examinations were done on the chain saw workers, and eighty seven subjects out of one hundred three workers were studied. No ear infections or hearing loss in past history were detected.The average hearing thresholds for 250, 500, 1, 000, 2, 000, 4, 000, 8, 000Hz in each decade were calculated by using a computer process. There were no remarkable differences of hearing loss in the lower frequencies than 2, 000Hz in each decade, but there were difference more than 20dB in 4, 000 and 8, 000Hz between the second and fifth decades. There were no significant difference according to the years of their experiences. It might be said that the hearing loss of the chain saw workers increased in accordance with the age, and their hearing loss were always worse than that of those working in office, but was better than that of those working in the noisy iron manufacturing industry.A typical pure tone audiogram for the chain saw workers was not a c-5 dip type, but a c-6 injured type. The hearing loss was found in fourteen percents in the second decade, twenty in the third, twenty two in the fourth, and thirty two percents in the fifth.

Hearing Impairment in the Nishizin Textile Weavers

Exposure to a loud noise in many years in some industries may cause hearing impairment.Average noise level in the Nishizin textile workshops was 94dB(A) at weaver's ear level and peak range of its frequency was 2, 000-3, 000Hz.105 patients with some otologic complaints who were working in the Nishizin textile workshops were statistically analyzed in the last 5 years.The patients were ranged 20-70 years old with 2-40 working years and male and female ratio was 2:3. Chief complaints were tinnitus (60%), hard of hearing (30%) and dizziness (8%), and the higher incidence was found between 40 years and 10 years of experience.Audiogram showed C5 dip type or high tone abrupt type in the most cases.The average hearing impairment over 40dB were 25%.The average hearing impairment in the workers below 20 years experience tended to become worse in proportion to the number of working years, however the proportion of hearing impairment to the working years was hardly found in the workers over 21 years experience.

Detailed Audiometry

Very slow frequency sweep (5 minutes and 40 seconds per 1 octave) was adopted in ordinary Békésy audiometry as a new method for detailed measurement of hearing threshold along the frequency scale. The purpcse of this paper is to ascertain the limitation of this method in the viewpoint of exact recording of the threshold curve. One hundred and three ears with high tone loss of abrupt or dip type were tested. As the result, it was observed that the correct threshold was obtained in 101 ears, and only two ears showed so sharp slope of the threshold curve that the trace coincided the maximum limit of this recording. Accodingly, it was concluded that the usefullness of this method was recognized.

New method for measuring lag time between human uterine contraction and the effect on fetal heart rate

Two types of fetal heart rate dips, commonly referred to as Types I and II dips, may occur under abnormal conditions during labor. The purpose of this paper is to describe a new method for analyzing the time relation between Type II dips and the corresponding amnictic fluid pressure wave. Instead of using only one point corresponding to the minimum of fetal heart rate plus one point from the peak of amniotic fluid pressure and taking the difference, this method comprehensively includes many points from each wave form. This circumvents large lag-time errors as illustrated by analysis of 16 wave-form pairs.

A Rotational Viscometer Capable of Precise Measurement at Very Low Rate of Shear

A rotational viscometer with high accuracy at very low rate of shear (0.05 1/s) is constructed. It is a viscometer of free suspension type which is devised so as to reduce the influence of surface tension and the error due to excentricity. The expected error of the measurement can be so small as 0.02%. By means of this apparatus an anomaly of dip type in the curve of ηsp/C vs. C for highly diluted solutions (ηsp≃0.05) of polystyrene (mol. wt. 9.7×104) in toluene is observed. For the same dilution of DNA in water with 0.1 mol. NaCl an anomaly of peak type is observed. These anomalies are quite similar to the anomalies Cragg and Bigelow have observed in ternary systems and interpreted as the effect of critical concentration.

STUDIES ON OCCUPATIONAL DEAFNESS

Lately, many methods of calculatiing the average hearing loss for occulational deafness are discussed. A new procedure for such a method is proposed and was centered on the tone range impaired and the pattern of the development of hearing impair-ment. A classifing criteria as shown in fig. was basedon the average hearing loss at the middle and hig-her frequency range. The air conduction audiograms in 237 persons (474 ears) working under the noise exposure in a certain factory could be divided in to 0, A and B groups. The chief results were as follow: 1) Occupational deafness was found in 66% of the screening test (1000, 4000 cps 20db).2) 0 group showed slight hearing loss under 20db at the middle and higher frequency range in 16% of 311 audiograms. 3) A group showed hearing loss under 20db at middle frequency range and over 20db at the higherfrequency range, in 57% of all ears. There appea-red in 41% a dip type hearing impairment with peaks around 4000cps in this group.Bad subjective symptom of hard-hearing. Fi-fty percent of this group. A considerable loss of hearing at 2000.--3000cps tone range was formd in many of this group. 4) B gooups showed loss over 20 db at the mid-dle and higher frequency range, in 14% in all ears. The number of afflicted ears increased as the year of service increased and were especially seen most frequently in those with records over 20 years of service. 5) The author found that the decrease of hea-ring tend to become worse in proportion to the nu-mber of working years. However, a significant diff-erence was not noticed in decibel hearing loss among the classfication of age in the group of working years.

Radioactivity of Oil-Well Drilling Fluid with Depth of Wells

holes as well as producing wells. Both studies were conducted in a similar manner and with the same apparatus, with the exception that Johnston used a Special Dip type counter tube while Drees' used a GIS gamma-ray tube. With Johnston's technique, the Dip type counter tube was partially immersed in the drilling fluid; while with Drees technique his GIS counter tube was held uniformly cm above each sample. Furthermore, Johnston used lead sheeting to screen his tube and fluid-sample, while Drees used 2 x 4 x 6 iron bricks for this purpose. Selection of Oil-Wells