Slope Of Psychometric Function Research Articles

The effects of variability on context effects and psychometric function slopes in speaking rate normalizationa).

Acoustic context influences speech perception, but contextual variability restricts this influence. Assgari and Stilp [J. Acoust. Soc. Am. 138, 3023-3032 (2015)] demonstrated that when categorizing vowels, variability in who spoke the preceding context sentence on each trial but not the sentence contents diminished the resulting spectral contrast effects (perceptual shifts in categorization stemming from spectral differences between sounds). Yet, how such contextual variability affects temporal contrast effects (TCEs) (also known as speaking rate normalization; categorization shifts stemming from temporal differences) is unknown. Here, stimuli were the same context sentences and conditions (one talker saying one sentence, one talker saying 200 sentences, 200 talkers saying 200 sentences) used in Assgari and Stilp [J. Acoust. Soc. Am. 138, 3023-3032 (2015)], but set to fast or slow speaking rates to encourage perception of target words as "tier" or "deer," respectively. In Experiment 1, sentence variability and talker variability each diminished TCE magnitudes; talker variability also produced shallower psychometric function slopes. In Experiment 2, when speaking rates were matched across the 200-sentences conditions, neither TCE magnitudes nor slopes differed across conditions. In Experiment 3, matching slow and fast rates across all conditions failed to produce equal TCEs and slopes everywhere. Results suggest a complex interplay between acoustic, talker, and sentence variability in shaping TCEs in speech perception.

Effects of quality of initial exposure stimuli on speech intelligibility

Listeners can use lexical information to drive adaptation to talker-specific speech characteristics with a small amount of exposure. This suggests that adaptation may be strongest when listeners are initially exposed to speech in a condition that facilitates word recognition. This was tested by examining the intelligibility of second-language (L2) speech-in-noise when stimuli were initially presented in Quiet versus low signal-to-noise ratio (SNR) conditions. Recordings of 10 L2 English talkers were tested. For each talker, 120 sentences were mixed with speech-shaped noise ranging from −4 dB to 8 dB in steps of 2 dB and in Quiet (15 sentences at each SNR). These stimuli were presented from lowest to highest SNR (forward; −4 dB to Quiet) in one group of L1 English listeners (n = 10/talker) and from highest to lowest SNR (reverse; Quiet to −4 dB) in the other (n = 10/talker). The results showed that early exposure to a clean signal led to better speech perception. At lower SNRs, word recognition accuracy in the reverse order was significantly higher than the forward order, resulting in a steeper slope of psychometric function of intelligibility in the forward versus reverse condition. The quality of initial speech input may influence talker adaptation, particularly in adverse listening conditions.

Development of a Phrase-Based Speech-Recognition Test Using Synthetic Speech.

Speech-recognition tests are widely used in both clinical and research audiology. The purpose of this study was the development of a novel speech-recognition test that combines concepts of different speech-recognition tests to reduce training effects and allows for a large set of speech material. The new test consists of four different words per trial in a meaningful construct with a fixed structure, the so-called phrases. Various free databases were used to select the words and to determine their frequency. Highly frequent nouns were grouped into thematic categories and combined with related adjectives and infinitives. After discarding inappropriate and unnatural combinations, and eliminating duplications of (sub-)phrases, a total number of 772 phrases remained. Subsequently, the phrases were synthesized using a text-to-speech system. The synthesis significantly reduces the effort compared to recordings with a real speaker. After excluding outliers, measured speech-recognition scores for the phrases with 31 normal-hearing participants at fixed signal-to-noise ratios (SNR) revealed speech-recognition thresholds (SRT) for each phrase varying up to 4 dB. The median SRT was -9.1 dB SNR and thus comparable to existing sentence tests. The psychometric function's slope of 15 percentage points per dB is also comparable and enables efficient use in audiology. Summarizing, the principle of creating speech material in a modular system has many potential applications.

The Psychometric Function for Focusing Attention on Pitch

What is the effect of focusing auditory attention on an upcoming signal tone? Weak signal tones, 40 ms in duration, were presented in 50 dB continuous white noise and were either uncued or cued 82 ms beforehand by a 12 dB SL cue tone of the same frequency and duration as the signal. Signal frequency was either constant for a block of trials or was randomly one of 11 frequencies from 632 to 3140 Hz. Slopes of psychometric functions for detection in single-interval (Yes/No) trials were obtained from three listeners by varying the signal level over a 1–9 dB range. Plots of log(d’) against signal dB were fit by linear functions. Slopes were similar whether signal frequency was constant or varied, as found by D. Green. Slopes for uncued tones increased by 14% to 20% more than predicted by signal energy (i.e., 0.10), as also found previously, whereas slopes for cued tones followed signal energy corrected for an 8 dB sensory threshold. That pre-cues help attention focus rapidly on signal frequency and permit listeners to act as near-ideal detectors of signal energy, which they do not do otherwise, supports a key hypothesis of Grossberg’s ART model that attention guided by conscious awareness can optimize perception.

Psychometrically Equivalent Fante Speech Recognition Threshold Materials by a Female Talker.

This study aimed to create and evaluate digitally recorded speech materials for speech recognition threshold (SRT) testing among children and adults in Fante. Fifty-one (51) familiar trisyllabic words were chosen from a list of 107 widely used trisyllabic Fante words. They were digitally captured and edited to create the same root mean square as a 1-kHz calibration tone. The study used a three-phase cross-sectional study method. Twenty native Fante speakers with normal hearing thresholds were selected at random for listener evaluation. For each of the words, the researchers used logistic regression to measure the slope, intercepts, and psychometric function slope at 50% and from 20% to 80%. In the study, the intensity of each word was modified digitally, so that the threshold at 50% of each word was equal to the mean pure-tone average (PTA) of the participants to increase the homogeneity of the thresholds of the selected words. A final list of 25 familiar homogenous words with the same tone patterns of slopes greater than 7%/dB was finally selected and recorded for speech audiometry in Fante. Psychometrically equivalent trisyllabic words in Fante were successfully developed and evaluated for SRT testing in Ghana. There is a need for the development of speech audiometry materials in other Ghanaian languages.

Contribution of listening effort and cognitive processing to psychometric functions during adolescence and young adulthood

Hearing and listening are critical to how adolescents communicate, learn new information, and engage with technology and culture. However, performance on auditory perceptual tasks takes a long time to mature. Age-related improvements in executive functions and other cognitive functions likely contribute to this long developmental trajectory. To examine how listening effort and cognition relate to psychometric functions on auditory perceptual tasks in adolescents and young adults, we used the method of constant stimuli to test 10- to 23-year-olds on frequency discrimination, temporal interval discrimination, and gap detection. During task performance, an eye tracker was used to measure pupil size and blink rate as proxies for listening effort or engagement. Typically, larger pupil size and fewer blinks are associated with higher engagement. All listeners also completed a battery of cognitive tests including tests of verbal and nonverbal reasoning, working memory, processing speed, and attention. We will demonstrate any changes in the estimated thresholds and psychometric function slopes during adolescence and will relate these developmental changes to individual differences in listening effort and cognition. [Work funded by NIDCD.]

Titrating effects of acoustic variability on context effects and psychometric function slopes in speech categorization

In temporal contrast effects (TCEs, also termed speaking rate normalization), a fast context sentence makes the onset of the subsequent target word sound longer, and vice versa. King, Sharpe, Shorey, and Stilp (2022 ASA) reported that variability in the talkers or lexical contents of context sentences each decreased TCE magnitudes. However, in that experiment, acoustic variability was not tightly controlled. Using the same stimuli as King et al., listeners completed three blocks, hearing one talker speaking the same sentence (1 Talker/1 Sentence) or 200 different sentences (1/200), or 200 different talkers speaking 200 different sentences (200/200). On each trial, listeners heard one (fast/slow) context sentence, then identified the subsequent target word as “deer” or “tier.” In one experiment, speaking rates were matched across 1/200 and 200/200 blocks; TCE magnitudes were comparable and psychometric slopes did not differ. In another experiment, all slow sentences were set to 2.67 syllables/sec and all fast sentences to 8 syllables/sec. Differences due to sentence variability (1/1 versus 1/200) were extinguished; TCE magnitudes were smaller and psychometric slopes were shallower in the 200/200 block. Thus, multiple levels of variability must be considered in how they shape speaking rate normalization. [Work supported by NIH R01DC020303.]

BPACE: A Bayesian, Patient-Centered Procedure for Matrix Speech Tests in Noise.

Matrix sentence tests in noise can be challenging to the listener and time-consuming. A trade-off should be found between testing time, listener's comfort and the precision of the results. Here, a novel test procedure based on an updated maximum likelihood method was developed and implemented in a German matrix sentence test. It determines the parameters of the psychometric function (threshold, slope, and lapse-rate) without constantly challenging the listener at the intelligibility threshold. A so-called "credible interval" was used as a mid-run estimate of reliability and can be used as a termination criterion for the test. The procedure was evaluated and compared to a STAIRCASE procedure in a study with 20 cochlear implant patients and 20 normal hearing participants. The proposed procedure offers comparable accuracy and reliability to the reference method, but with a lower listening effort, as rated by the listeners ( points on a 10-point scale). Test duration can be reduced by 1.3 min on average when a credible interval of 2 dB is used as the termination criterion instead of testing 30 sentences. Particularly, normal hearing listeners and well performing, cochlear implant users can benefit from shorter test duration. Although the novel procedure was developed for a German test, it can easily be applied to tests in any other language.

Impact of induced pseudomyopia and refractive fluctuations of accommodative spasm on visual acuity

ABSTRACT Clinical relevance High-contrast visual acuity is disproportionately poor in patients with accommodative spasm subtype of near reflex (SNR-A), relative to uncorrected refractive errors of equivalent magnitude. This exaggerated loss of performance in SNR-A may be explained by the combination of pseudomyopia and its fluctuations, vis-à-vis, each factor considered separately. Background To determine how combinations of pseudomyopic refraction and its temporal variations in SNR-A impact high-contrast visual acuity by inducing these patterns in healthy cyclopleged adults, relative to their baseline acuity. Methods Refractive profiles of 15 patients with SNR-A were obtained from a previous study, averaged, and induced before the right eye of 14 cyclopleged adults (mean ±1 SD age: 22.7 ± 2.6 yrs) by feeding the profile into a coaxially placed, motorised, Badal optometer. LogMAR acuity was measured using the method of constant stimuli: (1) before cycloplegia, (2) after cycloplegia and post-cycloplegia with (3) combination of pseudomyopia and its temporal fluctuations, (4) only pseudomyopia, (5) only temporal fluctuations in refraction about emmetropia, (6) condition 5 with double the amplitude of induced fluctuations and (7) condition 5 with half the amplitude of induced fluctuations. Results The induced refractive fluctuations ranged from −0.80 to −1.75D, around a mean pseudomyopia of −1.20D. Visual acuity deterioration was maximum for the combination of pseudomyopia and temporal fluctuations condition (0.51 ± 0.07logMAR), followed by only pseudomyopia (0.27 ± 0.05logMAR) and only refractive fluctuations conditions (0.17 ± 0.04logMAR), all relative to baseline post-cycloplegia (0.13 ± 0.04logMAR) (p < 0.001). Visual acuity loss increased with doubling of refractive fluctuations (0.20 ± 0.04logMAR), relative to native fluctuations or halving the amplitude (0.15 ± 0.03logMAR) (p < 0.01). Task precision, as adjudged from the slope of psychometric function, followed a similar pattern of loss as visual acuity. Conclusion Combination of induced pseudomyopia and temporal fluctuations in refraction produces an additive loss of visual acuity and task precision, relative to baseline and each factor considered separately.

DEVELOPMENT OF MACEDONIAN MONOSYLLABIC AND DISYLLABIC TESTS FOR SPEECH AUDIOMETRY

The aim of the study was to develop Macedonian monosyllabic and disyllabic tests for speech audiometry, to record the speech materials, and to conduct clinical validation of the tests. The following criteria were applied: word familiarity, phonetic balance, and homogeneity of audibility. Clinical validation was conducted on a sample of 30 normal hearing subjects, aged 18 to 30 years. We developed four open-set tests for speech threshold and suprathreshold testing in quiet. The tests contain two word lists with 50 monosyllabic words and two word lists with 36 disyllabic words. Each word was introduced by a carrier phrase. Psychometric function slope from 20% to 80% correct recognition for all words was 5%/ dB. The difference between the presentation levels at which the subjects repeated all the words was ≤ 4 dB. Developed phonetically balanced word lists have relatively steep psychometric function slope and they are homogeneous in terms of the audibility.

Development of SC-10: A psychometrically equivalent Singapore Mandarin disyllabic word list for clinical speech audiometry use.

ObjectiveThe aim of this study is to develop and evaluate a set of psychometrically equivalent disyllabic wordlist (SC-10) in Singapore Mandarin for clinical use.Study designA preliminary set of 1000 words were obtained from a dictionary of frequently used words by Singapore students. Ten native judges rate the familiarity level of each word. This is followed by a face-to-face public survey to rank the shortlisted word set from most to least familiar. The final 108 disyllabic words were recorded by a native female talker. 20 normal hearing subjects were used to obtain the percentage of correct word recognition at 24 intensity levels (−10 dB HL to 26 dB HL in 2 dB increment). Psychometric function slopes were calculated for each word. 100 words were eventually chosen and assigned into ten 10-word lists based on a psychometric balancing protocol. Minor digital adjustments were made to the intensity of each wordlist to improve their auditory homogeneity.The developed SC-10 wordlists were validated by a separate group of 25 normal hearing subjects. Test-retest reliability was carried out on 20 out of 25 participants at the selected intensity levels (SRT-5, SRT, SRT+5).ResultsThe calculated regression slopes in the psychometric functions for the ten lists are between 8.0 and 9.8%/dB. Single factor ANOVA analysis showed no significant difference in both the mean intensity required to obtain 50% recognition score (f = 0.109, df = 9, p = 0.999) and the slopes of the psychometric functions (f = 0.078, df = 9, p = 0.999) between the ten word lists. List validation on 25 normal hearing participants (PTA = 11.0 dB HL, SD = 4.3) showed a mean speech recognition threshold (SRT) of 9.3 dB HL (SD = 3.5)and regression slope of 8.395%/dB. Quadratic regression analysis showed a positive correlation (r2 = 0.923) between presentation level and word recognition score (WRS). The difference between PTA and SRT of each subject all fall within the clinically acceptable difference of 10 dB HL. Test-retest reliability, carried out on 20 subjects at three levels (SRT-5, SRT, and SRT+5 dB), showed no significance difference between word recognition score when the same participant is tested again at the same intensity level using a different wordlist.ConclusionAll in all, it shows that the SC-10 speech materials are valid for clinical use for Mandarin speech audiometry in Singapore.

Psychometric function characteristics of Persian consonantvowel-consonant words

Background and Aim: Evaluation of word recognition score requires multiple lists that must be similar in terms of difficulty level. There is currently no such word lists for the Persian language. The aim of this study was to construct several lists of Persian monosyllabic words with psychometric homogeneity. Methods: The most common monosyllabic words were collected from a book of Persian word frequency. The selected monosyllabic Consonant-Vowel-Consonant (CVC) words were presented randomly to 30 normal hearing participants with the age range of 18 to 25 years. The presentation level was from 0 to 40 dB in 8 dB increments. The characteristics of psychometric function were determined for all words using the logistic regression. Results: The Persian CVC monosyllabic words have different difficulty levels with threshold varying from 2.8 to 37.2 dB HL and the slope from 2.3 to 16.4 %/dB. Conclusion: The final result of the present study is three full lists of monosyllabic words with CVC syllabic structure that have the same mean threshold and slope of psychometric function. The 25-word half-lists of each full list are similar in terms of psychometric characteristics. Keywords: Psychometric function; Persian monosyllabic words; speech audiometry

Grouping Effects on Foveal Spatial Interactions in Children.

PurposeGrouping of flankers from the target can modulate crowding in adults. Visual acuity in children is measured clinically using charts with targets and different flankers to enhance spatial interactions. We investigated grouping effects on interactions using visual acuity letters, flanked by contours and letters, in children.MethodsVisual acuity for isolated and flanked letters was measured in 155 three- to 11-year old children and 32 adults. Flankers were one stroke width from the target and were a box or four bars and black or red letters. Magnitudes of interaction were flanked minus isolated logMAR acuities. Psychometric function slopes were also examined.ResultsMagnitudes of interaction by contours did not change significantly with age. They were 0.047 ± 0.014 logMAR more with bars than a box. Interaction from flanking letters reduced with age, adults being not different from 9- to 11-year-olds for black and red letter surrounds. It was weaker by 0.033 ± 0.013 logMAR when a black letter was surrounded by red rather than black letters. Psychometric function slopes for visual acuity were steepest for the youngest children (3–5 years).ConclusionsFor contour and letter flankers, grouping effects on interaction magnitude are age independent. Grouping bars into a box forming a single object reduces magnitude of effect. Grouping letter flankers by color and ungrouping them from the target reduce interaction magnitude by ∼8%, suggesting that luminance-defined form dominates. Differently colored letter flankers of high-luminance contrast on acuity charts could draw attention to the target but retain significant interaction strength.

Repeatability of Taste Recognition Threshold Measurements with QUEST and Quick Yes-No.

Taste perception, although vital for nutrient sensing, has long been overlooked in sensory assessments. This can, at least in part, be attributed to challenges associated with the handling of liquid, perishable stimuli, but also with scarce efforts to optimize testing procedures to be more time-efficient. We have previously introduced an adaptive, QUEST-based procedure to measure taste sensitivity thresholds that was quicker than other existing approaches, yet similarly reliable. Despite its advantages, the QUEST procedure lacks experimental control of false alarms (i.e., response bias) and psychometric function slope. Variations of these parameters, however, may also influence the threshold estimate. This raises the question as to whether a procedure that simultaneously assesses threshold, false-alarm rate, and slope might be able to produce threshold estimates with higher repeatability, i.e., smaller variation between repeated measurements. Here, we compared the performance of QUEST with a method that allows measurement of false-alarm rates and slopes, quick Yes–No (qYN), in a test–retest design for citric acid, sodium chloride, quinine hydrochloride, and sucrose recognition thresholds. We used complementary measures of repeatability, namely test–retest correlations and coefficients of repeatability. Both threshold procedures yielded largely overlapping thresholds with good repeatability between measurements. Together the data suggest that participants used a conservative response criterion. Furthermore, we explored the link between taste sensitivity and taste liking or which we found, however, no clear association.

Psychometric Functions of Vowel Detection and Identification in Long-Term Speech-Shaped Noise.

Purpose The goal of this study was to investigate vowel detection and identification in noise and provide baseline data regarding how vowel perception changed with signal-to-noise ratios. Psychometric functions of vowel detection and identification for 12 American English isolated vowels in long-term speech-shaped noise were examined for young listeners with normal hearing in this study. Method Vowel detection was measured at sensation levels from -10 to +5 dB (re: thresholds of vowel detection from the study of Liu and Eddins, 2008a ) with a 4-interval forced-choice procedure. Thresholds of vowel detection were computed for each listener as the speech level at which 70.7% correct performance was reached. Vowel identification was then examined at sensation levels from 0 to 12 dB relative to detection thresholds for each listener. Thresholds of vowel identification were calculated as the speech level with vowel identifiability ( d') equals to 1. Results Thresholds of vowel detection and identification were significantly affected by vowel category. Slopes of psychometric functions of vowel identification were significantly dependent on vowel category, whereas slopes of psychometric functions of vowel detection were not. Conclusions These results suggest that, given the same sensation levels, especially at low sensation levels, vowel sounds are not equally perceivable in terms of identifiability.

The motor system's [modest] contribution to speech perception.

Recent evidence suggests that the motor system may have a facilitatory role in speech perception during noisy listening conditions. Studies clearly show an association between activity in auditory and motor speech systems, but also hint at a causal role for the motor system in noisy speech perception. However, in the most compelling "causal" studies performance was only measured at a single signal-to-noise ratio (SNR). If listening conditions must be noisy to invoke causal motor involvement, then effects will be contingent on the SNR at which they are tested. We used articulatory suppression to disrupt motor-speech areas while measuring phonemic identification across a range of SNRs. As controls, we also measured phoneme identification during passive listening, mandible gesturing, and foot-tapping conditions. Two-parameter (threshold, slope) psychometric functions were fit to the data in each condition. Our findings indicate: (1) no effect of experimental task on psychometric function slopes; (2) a small effect of articulatory suppression, in particular, on psychometric function thresholds. The size of the latter effect was 1 dB (~5% correct) on average, suggesting, at best, a minor modulatory role of the speech motor system in perception.

Psychometric function slope for speech-in-noise and speech-in-speech: Effects of development and aging.

Masked sentence recognition was evaluated in normal-hearing children (8.8-10.5 years), young adults (18-28 years), and older adults (60-71 years). Consistent with published data, speech recognition thresholds were poorer for young children and older adults than for young adults, particularly when the masker was composed of speech. Psychometric function slopes were steeper for young children and older adults than for young adults when the masker was two-talker speech, but not when it was speech-shaped noise. Multiple factors are implicated in the age effects observed for speech-in-speech recognition at low signal-to-noise ratios.

Neuronal adaptation to sound statistics in the inferior colliculus of behaving macaques does not reduce the effectiveness of the masking noise.

The detectability of target sounds embedded within noisy backgrounds is affected by the regularities that summarize acoustic sceneries. Previous studies suggested that the dynamic range of neurons in the inferior colliculus (IC) of anesthetized guinea pigs shifts toward the mean sound pressure level in irregular acoustic environments. Yet, it is unclear how this neuronal adaptation processes may influence the effectiveness of sounds as a masker, both behaviorally and in terms of neuronal encoding. To answer this question, we measured the neural response of IC neurons while macaque monkeys performed a Go/No-Go tone detection task. Macaques detected a 50-ms tone that was either simultaneously gated with a burst of noise or embedded within a continuous noise background, whose levels were randomly sampled (every 50 ms) from a probability distribution. The mean of the distribution matched the level of the gated burst of noise. Psychometric and IC neurometric thresholds to tones did not differ between the two masking conditions. However, the neuronal firing rate versus level function was significantly affected by the temporal characteristics of the noise masker. Simultaneously gated noise caused higher baseline responses and greater dynamic range compression compared with noise distribution. The slopes of psychometric and neurometric functions were significantly shallower for higher variance distributions, suggesting that neuronal sensitivity might change with the variability of the sound. Our results suggest that the adaptive response of IC neurons to sound regularities does not affect the effectiveness of the noise-masking signal, which remains invariant to surrounding noise amplitudes. NEW & NOTEWORTHY Auditory neurons adapt to the statistics of sound levels in the acoustic scene. However, it is still unclear to what extent such adaptation influences the effectiveness of the stimulus as a masker. Our study represents the first attempt to investigate how the adaptation to the statistics of masking stimuli may be related to the effectiveness of masking, and to the single-unit encoding of the midbrain auditory neurons in behaving animals.

Auditory Synaptopathy and Masking Psychometric Function Slope: A Conjecture

Auditory Synaptopathy and Masking Psychometric Function Slope: A Conjecture

Development of a Thai phonetically balanced monosyllabic word recognition test: Derivation of phoneme distribution, word list construction, and response evaluations

This paper proposes a test tool for Thai word recognition, the Thammasat University Phonetically Balanced Word List 2014 (TU PB’14), standardized on several major criteria: phonemic balance, familiarity, reliability, list equivalency, and homogeneity. Phoneme distributions from the largest written Thai corpus (InterBEST) were obtained and used to construct five phonetically balanced word lists, each containing 25 frequently occurring monosyllabic words. Listeners’ percent correct discrimination scores from test and re-test sessions were not significantly different, confirming test reliability. Detailed analysis of listeners’ errors revealed that perceptual errors occurred predominantly for initial sound only, final only, and initial together with final. In terms of list equivalency and homogeneity, derived psychometric function slopes of TU PB’14 ranged from 0.0941 to 0.1155, while intensities required for 50% intelligibility ranged from 41.0279 to 41.3697. Two-way Chi-Square analysis performed on both parameters indicated that there was no significant difference among the word lists.