Repeatability of an automated ETDRS contrast threshold measurement

2021 ◽  
Author(s):  
Yi Pang ◽  
Lauren Sparschu ◽  
Jingyun Wang
Keyword(s):  
Contrast Threshold ◽  
Threshold Measurement

scholarly journals Contrast threshold measurement system in N and PSC cataract

2013 ◽  
Vol 13 (15) ◽  
pp. P15-P15
Author(s):  
C. Paz ◽  
R. Sanchez ◽  
E. Colombo ◽  
L. Issolio
Keyword(s):  
Measurement System ◽  
Contrast Threshold ◽  
Threshold Measurement

Optimizations for the Electrically-Evoked Stapedial Reflex Threshold Measurement in Cochlear Implant Recipients

2017 ◽  
Vol 38 (2) ◽  
pp. 255-261 ◽  
Author(s):  
Jace Wolfe ◽  
Melanie Gilbert ◽  
Erin Schafer ◽  
Leonid M. Litvak ◽  
Anthony J. Spahr ◽  
...  
Keyword(s):  
Cochlear Implant ◽  
Stapedial Reflex ◽  
Reflex Threshold ◽  
Threshold Measurement

Differential contributions of magnocellular and parvocellular pathways to the contrast response of neurons in bush baby primary visual cortex (V1)

2000 ◽  
Vol 17 (1) ◽  
pp. 71-76 ◽  
Author(s):  
JOHN D. ALLISON ◽  
PETER MELZER ◽  
YUCHUAN DING ◽  
A.B. BONDS ◽  
VIVIEN A. CASAGRANDE
Keyword(s):  
Visual Cortex ◽  
Primary Visual Cortex ◽  
Response Amplitude ◽  
Contrast Threshold ◽  
Peak Response ◽  
V1 Neurons ◽  
Bush Baby ◽  
High Stimulus ◽  
Average Contrast ◽  
Contrast Response

How neurons in the primary visual cortex (V1) of primates process parallel inputs from the magnocellular (M) and parvocellular (P) layers of the lateral geniculate nucleus (LGN) is not completely understood. To investigate whether signals from the two pathways are integrated in the cortex, we recorded contrast-response functions (CRFs) from 20 bush baby V1 neurons before, during, and after pharmacologically inactivating neural activity in either the contralateral LGN M or P layers. Inactivating the M layer reduced the responses of V1 neurons (n = 10) to all stimulus contrasts and significantly elevated (t = 8.15, P < 0.01) their average contrast threshold from 8.04 (± 4.1)% contrast to 22.46 (± 6.28)% contrast. M layer inactivation also significantly reduced (t = 4.06, P < 0.01) the average peak response amplitude. Inactivating the P layer did not elevate the average contrast threshold of V1 neurons (n = 10), but significantly reduced (t = 4.34, P < 0.01) their average peak response amplitude. These data demonstrate that input from the M pathway can account for the responses of V1 neurons to low stimulus contrasts and also contributes to responses to high stimulus contrasts. The P pathway appears to influence mainly the responses of V1 neurons to high stimulus contrasts. None of the cells in our sample, which included cells in all output layers of V1, appeared to receive input from only one pathway. These findings support the view that many V1 neurons integrate information about stimulus contrast carried by the LGN M and P pathways.

Verification of In Situ Thresholds and Integrated Real-Ear Measurements

2010 ◽  
Vol 21 (10) ◽  
pp. 663-670 ◽  
Author(s):  
Jeffrey J. DiGiovanni ◽  
Ryan M. Pratt
Keyword(s):  
Measurement System ◽  
Hearing Aids ◽  
Hearing Aid ◽  
Normal Hearing ◽  
Analysis Tool ◽  
Ohio University ◽  
Positive Direction ◽  
Significant Difference ◽  
Threshold Measurement

Background: Accurate prescriptive gain results in a more accurate fit, lower return rate in hearing aids, and increased patient satisfaction. In situ threshold measurements can be used to determine required gain. The Widex Corporation uses an in situ threshold measurement strategy, called the Sensogram. Real-ear measurements determine if prescriptive gain targets have been achieved. Starkey Laboratories introduced an integrated real-ear measurement system in their hearing aids. Purpose: To determine whether the responses obtained using the Widex Sensogram were equivalent to those obtained using current clinical threshold measurement methods. To determine the accuracy of the Starkey IREMS™ (Integrated Real Ear Measurement System) in measuring RECD (real-ear to coupler difference) values compared to a dedicated real-ear measurement system. Research Design: A verification design was employed by comparing participant data measured from standard, benchmark equipment and procedures against new techniques offered by hearing-aid manufacturers. Study Sample: A total of 20 participants participated in this study. Ten participants with sensorineural hearing loss were recruited from the Ohio University Hearing, Speech, and Language Clinic participated in the first experiment. Ten participants with normal hearing were recruited from the student population at Ohio University participated in both experiments. The normal-hearing group had thresholds of 15 dB HL or better at the octave frequencies of 250–8000 Hz. The hearing-impaired group had thresholds of varying degrees and configurations with thresholds equal to or poorer than 25 dB HL three-frequency pure-tone average. Data Collection and Analysis: The order of measurement method for both experiments was counterbalanced. In Experiment 1, thresholds obtained via the Widex Sensogram were compared to thresholds obtained for each participant using a clinical audiometer and ER-3A insert ear phones. In Experiment 2, RECD values obtained via the Starkey IREMS were compared to RECD values obtained via the Audioscan Verifit™. A repeated-measures analysis of variance (ANOVA) was used for statistical analysis, and a Fisher's LSD (least significant difference) was used as a post hoc analysis tool. Results: A significant difference between Sensogram thresholds and conventional audiometric thresholds was found with the Sensogram method resulting in better threshold values at 0.5, 1.0, and 2.0 kHz for both groups. In Experiment 2, a significant difference between RECD values obtained by the Starkey IREMS and the Audioscan Verifit system was found with significant differences in RECD values found at 0.25, 0.5, 0.75, 1.5, 2.0, and 6.0 kHz. Conclusions: The Sensogram data differ significantly from traditional audiometry at several frequencies important for speech intelligibility. Real-ear measures are still required for verification of prescribed gain, however, calling into question any claims of shortened fitting time. The Starkey IREMS does perform real-ear measurements that vary significantly from benchmark equipment. These technologies represent a positive direction in prescribing accurate gain during hearing-aid fittings, but a stand-alone system is still the preferred method for real-ear measurements in hearing-aid fittings.

Design of Time-to-digital Converters for Time-over-threshold Measurement in Picosecond Timing Detectors

2021 ◽  
pp. 1-1
Author(s):  
Bo Wu ◽  
Yonggang Wang ◽  
Qiang Cao ◽  
Ziwei Li ◽  
Xin Li ◽  
...  
Keyword(s):  
Threshold Measurement

Qualitatively Different Effects of Undetected and Unidentified Auditory Primes

1988 ◽  
Vol 40 (2) ◽  
pp. 323-339 ◽  
Author(s):  
J. A. Groeger
Keyword(s):  
Semantic Priming ◽  
Forced Choice ◽  
Sentence Completion ◽  
Semantic Activation ◽  
Unconscious Processing ◽  
Priming Stimulus ◽  
Completion Task ◽  
Threshold Measurement

The suggestion that semantic activation can occur without conscious identification of the priming stimulus is still controversial. Many studies supporting such a contention, especially those where primes were auditorially presented, suffer from methodological shortcomings, frequently with regard to threshold measurement. In the study reported here 24 subjects underwent a considerably more rigorous thresholding procedure than has been usual, prior to engaging in a forced-choice sentence completion task. The results show that semantic priming operates when subjects were unable to detect the presence of primes and that phonological (but not semantic) priming operates when the primes were invariably detected but never correctly identified. The relevance of these qualitatively different effects of primes, as a function of the level at which they are presented, in discussed in the light of recent accounts of unconscious processing.

Guidelines for Auditory Threshold Measurement for Significant Threshold Shift

2016 ◽  
Vol 37 (8) ◽  
pp. e263-e270 ◽  
Author(s):  
Kathleen Campbell ◽  
Tanisha Hammill ◽  
Michael Hoffer ◽  
Jonathan Kil ◽  
Colleen Le Prell
Keyword(s):  
Auditory Threshold ◽  
Threshold Shift ◽  
Threshold Measurement
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