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Biomedical subjects

R H Wilson

Publications and source records attributed to R H Wilson.

At least 109 records · Page 6Linked to original sources
PubMed1984

Tympanometric changes at 226 Hz and 678 Hz across 10 trials and for two directions of ear canal pressure change.

The influence that repeated tympanometric trials have on the aural-acoustic admittance characteristics of the middle-ear transmission system was studied in 24 young adults. The 226-Hz and 678-Hz data were generated by concurrently digitizing the conductance and admittance tympanograms at 25 daPa/s for both ascending and descending pressure directions. Ten successive trials for each frequency and direction of pressure change were made. Changes in admittance corrected for ear canal volume across the 10 tympanometric trials were computed. The results demonstrated that generally admittance increases as the number of trials increases. For many subjects, the complexity of the tympanometric configuration also increases across trials. The results from eight subjects with single-peaked 678-Hz tympanograms were compared with the results from eight subjects with notched 678-Hz tympanograms to explain the mean decrease in susceptance across tympanometric trials. Finally, the pressure peak locations of the conductance, susceptance, and admittance tympanograms were evaluated and are discussed. The effects that differences in peak pressure location have on the computed static admittance values are presented.

Acoustic Impedance Tests↗
PubMed1984

Masking-level difference in filtered-random and amplitude-modulated noise.

The masking characteristics of filtered-random noise and amplitude-modulated noise (40-dB pressure-spectrum level) were studied in a series of four experiments using a masking-level difference paradigm, that is, 500-Hz thresholds in S0N0 and SpiN0 binaural conditions. In Experiment 1 a filtered noise (200-800 Hz) and an amplitude-modulated noise (425-575 Hz) produced equal thresholds in S0N0; for SpiN0, however, the thresholds in amplitude-modulated noise were 1.6 dB lower than were the thresholds in filtered noise. In Experiment 2 S0N0 and SpiN0 thresholds were established in three filtered noise bandwidths (200-800 Hz, 335-685 Hz, and 410-600 Hz) and in the amplitude-modulated noise (425-575 Hz). When the bandwidths of the filtered-random and amplitude-modulated noises were similar, the SpiN0 thresholds were the same but the S0N0 thresholds were different. Experiments 3 and 4 indicated that with amplitude-modulated noise when the zero amplitude crossings of the tone and the noise coincided, the S0N0, SpiN0, and SmNm thresholds were 1.2-2.0 dB higher than were the thresholds when the zero crossings of the tone and noise did not coincide. The data indicate that the masking characteristics of filtered-random noise and amplitude-modulated noise are different. The findings are interpreted as an indication that perceptual phenomena depend on the temporal characteristics as well as the power spectrum of the signal and masker.

Adult↗
PubMed1984

Word recognition with segmented-alternated CVC words: a preliminary report on listeners with normal hearing.

Consonant-vowel-consonant (CVC) monosyllabic words were segmented at the approximate phoneme boundaries and were presented to subjects with normal hearing in the following sequence: (a) the carrier phrase to both ears, (b) the initial consonant segment to one ear, (c) the vowel segment to the other ear, and (d) the final consonant segment to the ear that received the initial consonant. A computer technique, which is described in detail, was used to develop the test materials. The digital editing did not alter appreciably the spectral or temporal characteristics of the words. A series of four experiments produced a list of 50 words on which 10% correct word recognition was achieved by listeners with normal hearing when the vowel segment or the consonant segments of the words were presented monaurally in isolation. When the speech materials were presented binaurally--that is, the vowel segment in one ear and consonant segments in the other ear--word-recognition performance improved to 90% correct.

Adult↗
PubMed1984

Acoustic-reflex adaptation: morphology and half-life data for subjects with normal hearing.

Acoustic-reflex adaptation was studied in 35 subjects with normal hearing using nine pure-tone activators (250-6000 Hz) and a broadband-noise activator. The individual subject data generated by the 31-s activators presented 10 dB above the reflex threshold were digitized, corrected for baseline drift and ear canal volume, and analyzed in terms of the acoustic-admittance change in acoustic mmhos and in terms of the percentage of maximum-reflex magnitude. Reflex adaptation increased as a function of frequency. The adaptation functions for the lower frequencies (less than or equal to 1500 Hz) were essentially linear over the 31-s activator period, whereas the functions for the higher frequencies (greater than or equal to 2000 Hz) were curvilinear over the activator period. The experimental half-life data are compared with a theoretical half-life function that was generated to estimate normal acoustic-reflex adaptation as a function of activator frequency. Finally, the means and standard deviations are reported and discussed for (a) the onset time of adaptation, (b) the half-life time, and (c) the percentage of maximum reflex magnitude at 5-s intervals from 5 to 30 s.

Acoustic Stimulation↗
PubMed1982

Detection and recognition masking-level differences for the individual CID W-1 spondaic words.

The detection and recognition masking-level differences for the 36 individual CID W-1 spondaic words (Technisonic Studios) were established on 36 listeners with normal hearing. The masking for two conditions, SoNo and S pi No, was accomplished with 70-dB-SPL speech-spectrum noise. The word lists were administered in 2-dB decrements with the 36 words presented at each signal-to-noise ratio, which ranged from 9 dB to -19 dB for SoNo and from 3 dB to -25 dB for S pi No. The detection and recognition thresholds determined for each spondaic word under both masking conditions are presented. Additionally, the slopes of the psychometric functions for each word under both conditions are given. The mean masking-level difference (SoNo-S pi No) for the detection-response task was 9.4 dB (SD = .7 dB). The mean masking-level difference for the recognition task was 7.2 dB (SD = 1.4 dB). The recognition masking-level differences for the individual spondaic words ranged from 4.4 dB (stairway) to 10.0 dB (oatmeal). A list of 10 words that had the largest masking-level differences for recognition is suggested to enhance the clinical utility of the masking-level difference for speech.

Auditory Threshold↗
PubMed1982

Recognition masking-level differences for 10 CID W-1 spondaic words.

Psychometric functions for the S omicron N omicron and S pi N omicron conditions and masking level differences were obtained for a subgroup of 10 words having the largest masking-level differences of 36 CID W-1 spondaic words. The mean masking-level difference obtained from 36 young normal adults was 9.4 dB with a standard deviation of 1.2 dB. The smallest masking-level difference of 7.4 dB was suggested as the low cut-off for normalcy. A shorter version of the masking-level difference procedure was suggested for clinical implementation. The subgroup of 10 words may permit a wider separation between normal and abnormal performance, and thus may enhance the clinical utility of the masking-level difference task for speech recognition. Because the magnitude of the masking-level difference will vary with the materials and procedures used, each clinic must establish its own norms.

Adult↗
PubMed1982

A technique for detecting the ipsilateral acoustic reflex.

A technique was explored for detecting the ipsilateral acoustic reflex using one acoustic signal (226-HZ tone) both to elicit the reflex and to measure the impedance of the ear. By eliminating the presentation of two acoustic signals to the same ear, artifactual responses that result from interactions between two signals are avoided. The method provided reflex threshold estimates for five normal subjects that averaged 99.8 dB SPL, in close agreement with previously reported data. A sixth subject, with otosclerosis, showed no evidence of a reflex. With some refinement, the method could become a quick, reliable measurement procedure that avoids some of the problems of conventional methods.

Acoustic Impedance Tests↗
PubMed1981

Aural acoustic-immittance measurements: inter-aural differences.

Bilateral measurements of the aural acoustic-immittance characteristics of the middle-ear transmission system of 48 subjects were made with an acoustic-admittance meter. The measurements, including static acoustic-immittance, acoustic-reflex thresholds, and acoustic-reflex growth functions, were made using a 220-Hz probe. The contralateral reflex data for three pure tones (500, 1000, and 2000 Hz) and for broadband noise were acquired in 2-dB steps at sound-pressure levels from 84-116 dB (tones) and 66-116 dB (noise) during ascending- and descending-intensity level runs. For all acoustic-immittance measurements, right ear and left ear comparisons were made and found not to be significantly different. The individual subject data then were expressed as the absolute differences between ears. In this manner normative inter-aural immittance differences were defined. The peak static immittance data were analyzed in terms of median inter-aural differences and upper 80% cut-off values. The 80% ranges for normal immittance values were smaller for a within subject versus an across subject comparison. For acoustic-reflex thresholds, a disparity between ears of greater than 10 dB was suggested as indicative of an abnormality in the auditory mechanism. Finally, the reflex-growth data indicated mean inter-aural absolute differences that ranged to .040-.043 acoustic mmhos (300-400 acoustic ohms) at the higher reflex activator sound-pressure levels.

Acoustic Impedance Tests↗
PubMed1981

The effects of aging on the magnitude of the acoustic reflex.

Aural acoustic-immittance (admittance and impedance) measurements during the quiescent and reflexive states were made using a computer sampling technique on 18 subjects with normal hearing in each of two age groups (less than 30 years and greater than 50 years). Seven pure-tones (250-6000 Hz) and broadband-noise stimuli served to elicit the acoustic reflex at sound-pressure levels from 84-116 dB (tones) and 66-116 dB (noise) in 2-dB steps during ascending and descending runs. The contralateral middle-ear activity was monitored with a 220-Hz probe by digitizing the conductance and susceptance outputs of an acoustic-admittance meter. The computer corrected for the immittance characteristics of the ear-canal volume by utilizing measurements made at an ear-canal pressure of -350 daPa and then by converting the conductance and susceptance values into admittance and impedance units. The results are reported as the immittance change between the quiescent and reflexive states as a function of both the activator sound-pressure level and the activator-pressure level above the reflex threshold. There were no significant differences between the static-immittance values for the two groups. Although acoustic-reflex thresholds for the two groups were the same in the low- to mid-frequency region (250-2000 Hz), the reflex thresholds for the greater than 50-years group were elevated significantly (approximately 8 dB) for 4000 Hz, 6000 Hz, and noise activators. In all conditions, the magnitude of the acoustic reflex was substantially smaller for the greater than 50-years group as compared with the less than 30-years group. The variability of the reflex magnitude was large for both groups of subjects. Saturation of the individual growth functions, which was frequency dependent, occurred twice as often with the greater than 50-years group as with the less than 30-years group. The relationship between the magnitude changes in conductance and susceptance from the quiescent to the reflexive state was the same for the two groups. Finally, the magnitude differences among the reflex-growth data were not related to differences in static immittance.

Acoustic Impedance Tests↗
PubMed1981

Digestion in the pig between 7 and 35 d of age. 1. The performance of pigs given milk and soya-bean proteins.

1. One hundred and fourteen pigs between 7 and 35 d of age were given diets containing milk or soya-bean proteins in four separate experiments. 2. The substitution of milk protein by soya-bean meal (SBM) to 75% of the total dietary protein reduced the weight gains and food conversion efficiencies of the pigs by 85% between 7 and 14 d of age and 31% between 21 and 28 d of age. 3. The treatment of soya-bean protein with alkali did not improve the performance of the pigs. 4. The substitution of milk protein by two different isolated soya-bean proteins (ISP) resulted in weight gains of 34 and 60% of te gains of pigs given milk protein diets. 5. Supplementation of the soya-bean-protein diets with methionine to 13 . 7 g/kg (5 g/16 g nitrogen) resulted in reduced food intakes and weight gains of the pigs and a 20-fold increase in the concentration of methionine in the blood plasma. 6. Supplementation of soya-bean-protein diets with lysine to 22 g/kg (8 g/16 g N) in addition to methionine doubled the concentration of lysine in the blood plasma. 7. The apparent digestibility (AD) of dry matter (DM) and N of the diets containing soya-bean protein increased with increasing age of the pigs, but the AD of the milk-protein diet was not affected by the age of the pigs. The retention of N as a percentage of the N intake increased from 57--67% for soya-bean protein over the duration of the experiments while the average value for the milk-fed pigs was 85% at all ages. 8. At 35 d of age, the fat content of the carcasses of the pigs given the ISP diet was 249 g/kg DM compared to 164 g/kg DM for the pigs given the milk diets.

Aging↗
PubMed1981

Digestion in the pig between 7 and 3 d of age. 2. The digestion of dry matter and the pH of digesta in pigs given milk and soya-bean proteins.

1. In two separate experiments, forty-four pigs weaned at 4--5 d of age were given diets containing milk or soya-bean proteins until slaughtered at 14, 28 or 35 d of age. 2. The retention times of digesta in the stomach and the entire gastro-intestinal tract did not differ between pigs given pelleted diets containing milk or soya-bean protein. 3. Digesta retention times in the stomach were shorter (61 v. 145 min) in pigs given a milk-protein diet in a liquid form than in pigs given the same diet in a pelleted form. The retention times in the whole gastro-intestinal tract were 42 . 8 v. 29 . 6 h on the respective diets. 4. The total retention time of digesta in the gastro-intestinal tract increased with age of pigs between 14--35 d of age when given pelleted diets but not when given a liquid diet. 5. The daily amount of digesta flowing through the anterior small intestine was unaffected by the source of protein. Greater endogenous secretions into the anterior small intestine were observed when pigs were fed ad lib. than when fed at 2 g nitrogen (45 d dry matter (DM)/kg live weight 0 . 75 per d. 6. The apparent digestion of DM to the ileum of pigs given milk, isolated soya-bean protein (ISP) (Promine D) or soya-bean meal (SBM) protein at 28 d of age was 0 . 826, 0 . 825 and 0 . 644 respectively. 7. The apparent digestion of DM to the ileum of pigs given ISP (Supro 610) significantly increased with age of pigs from 0 . 851 at 14 d of age to 0 . 883 at 35 d of age. No increase was observed for pigs given milk protein. 8. Differences in the digestibility of DM between protein sources were greater to the ileum than over the entire gastro-intestinal tract. The greatest increase in DM digestion from the ileum to the faeces occurred in pigs given SBM (0 . 644--0 . 874). 9. Neither the protein source nor age of pigs influenced gastric pH values, the mean value being 4 . 05. pH increased along the small intestine and was not affected by the protein source of age of pig.

Aging↗
PubMed1981

Digestion in the pig between 7 and 3 d of age. 3. The digestion of nitrogen in pigs given milk and soya-bean proteins.

1. In two separate experiments, forty-four pigs weaned at 4--5 d of age were fed on diets containing milk or soya-bean protein until slaughtered at 14, 28 or 35 d of age. 2. Daily amounts of nitrogen flowing through the stomach and proximal small intestine of pigs were similar with both sources of protein fed. 3. Endogenous N flows in the duodenum, jejunum and ileum of pigs given an N-free diet were 22 . 9, 7 . 4 and 4 . 6 g N/kg dry matter (DM) intake. Endogenous N in faeces was 0 . 970 g N/kg DM intake. 4. The apparent and true digestibility of N to the ileum of 28-d-old pigs was 0 . 86 and 0 . 92 for the pigs given the milk-protein diets, 0 . 80 and 0 . 86 for the pigs given the isolated soya-bean protein (ISP; Promine D) diets and 0 . 51 and 0 . 62 for pigs given the soya-bean meal (SBM)-protein diet. These values over the entire gastro-intestinal tract were 0 . 98 and 1 . 00 for milk, 0 . 92 and 0 . 95 for ISP and 0 . 82 and 0 . 85 for SBM. 5. The apparent and true digestibility of N to the ileum of 14-d-old pigs given a liquid milk diet was 0 . 92 and 0 . 94, while the values for the pigs given a pelleted milk diet were 0 . 86 and 0 . 87. At 35 d of age there were no differences in the apparent digestibility of the N in the liquid an pelleted milk diets. 6. The apparent digestibility of N to the ileum and over the entire gastro-intestinal tract of pigs given ISP (Supro 610) increased with increasing age of pigs from 0 . 83 at 14 d of age to 0 . 88 at 35 d of age. 7. Of the N in the stomach 14--32% could not be precipitated by trichloroacetic acid (TCA; 30 milligram). 8. In the jejunal and ileal contents an average of 46 and 24% of the N was precipitated by TCA in pigs given soya-bean proteins and milk proteins respectively.

Aging↗
PubMed1981

Digestion in the pigs between 7 and 35 d of age. 4. The digestion of amino acids in pigs given milk and soya-bean proteins.

1. In two experiments, forty-four pigs weaned at 4--5 d of age were given diets containing milk or soya-bean proteins until slaughtered at 14, 28, or 35 d of age. 2. Additions of methionine and methionine plus lysine to the diets did not increase the proportions of these amino acids in ileal digesta. 3. In the pigs given a nitrogen-free diet, ileal digesta contained more threonine, proline and glycine than in pigs given diets containing protein. 4. The apparent and true digestibility of amino acids were greater when milk protein was fed than when soya-bean proteins were fed. 5. The apparent digestion of amino acids to the ileum of pigs given isolated soya-bean protein (ISP; Supro 610) increased with increasing age of pigs from a mean of 0 . 82 at 14 d of age to 0 . 87 at 35 d of age. 6. When milk protein was fed apparent digestibilities of methionine and lysine to the ileum were 0 . 912 and 0 . 905. The apparent digestibility of threonine to the ileum was 0 . 800, 0 . 774 and 0 . 504 for pigs given the milk-, ISP and soya-bean-meal (SBM)-protein diets respectively. 7. Apparent digestibilities of total essential and non-essential amino acids were 0 . 79 and 0 . 69 respectively, and true digestibilities of both were 0 . 82.

Aging↗
PubMed1981

Digestion in the pig between 7 and 35 d of age. 5. The incorporation of amino acids absorbed in the small intestines into the empty-body gain of pigs given milk or soya-bean proteins.

1. In two separate experiments, forty-two pigs weaned at 4--5 d of age were given diets containing milk or soya-bean protein and slaughtered at 7, 28 or 35 d of age. 2. The amino acid composition of the empty body of the pigs did not vary with age or sources of protein fed. 3. The nitrogen and amino acid contents of the empty body gain were calculated between 7 and 28, and 7 and 35 d of age. The retention of absorbed N was greater in pigs given a soya-bean meal (SBM) diet than in pigs given milk or isolated soya-bean protein (ISP) diets. 4. The retention of total absorbed N was greater in pigs given a pelleted milk diet (0 .72) than in pigs given a liquid milk diet (0 . 58). 5. Methionine and threonine appeared to be the first two limiting amino acids, as indicated by their high incorporation into the empty body, for pigs given soya-bean proteins in Expt 3, while methionine and lysine were the first two limiting amino acids for pigs given ISP in Expt 4. 6. The addition of methionine to diets in Expt 3 reduced the retention of absorbed methionine in the empty body by 43--76%. Lysine supplementation did not alter the retention of the absorbed lysine. 7. Retention of arginine, proline and glycine in the body was greater than the apparent absorption of each of these amino acids.

Aging↗
PubMed1980

A picture identification task as an estimate of the word-recognition performance of nonverbal adults.

The Picture Identification Task was developed to estimate the word-recognition performance of nonverbal adults. Four lists of 50 monosyllabic words each were assembled and recorded. Each test word and three rhyming alternatives were illustrated and photographed in a quadrant arrangement. The task of the patient was to point to the picture representing the recorded word that was presented through the earphone. In the first experiment with young adults, no significant differences were found between the Picture Identification Task and the Northwestern University Auditory Test No. 6 materials in an open-set response paradigm. In the second experiment, the Picture Identification Task with the picture-pointing response was compared with the Northwestern University Auditory Test No. 6 in both an open-set and a closed-set response paradigm. The results from this experiment demonstrated significant differences among the three response tasks. The easiest task was a closed-set response to words, the next was a closed-set response to pictures, and the most difficult task was an open-set response. At high stimulus-presentation levels, however, the three tasks produced similar results. Finally, the clinical use of the Picture Identification Task is described along with preliminary results obtained from 30 patients with various communicative impairments.

Adult↗
PubMed1980

Acoustic-reflex thresholds for noise stimuli.

The effect of noise bandwidth on the acoustic-reflex threshold was studied in 12 normal-hearing adult subjects by independently varying the cutoff frequencies of low-pass (fL = 100 Hz) and high-pass (fH = 6000 Hz) computer-generated noises. Adjusting the cutoff frequency of the low-pass or high-pass activating stimuli over the 700-6000 Hz range resulted in a change in the reflex threshold of 4 dB/octave. As the cutoff frequency of the low-pass noise was reduced below 700 Hz, more rapid increases in reflex thresholds occurred. For high-pass stimuli, very small changes in reflex thresholds were noted as the lower cutoff frequency was increased from 100 to 700 Hz. The data suggest that between 700 and 6000 Hz equal spectral regions of a noise stimulus contribute equally to the reflex threshold, and that energy below 700 Hz contributes little to the sensitivity of the reflex.

Acoustic Stimulation↗