High-predictability Sentences Research Articles

Listener bias and intelligibility of unfamiliar varieties of a language

Speech intelligibility depends on a combination of the speech itself and of the listener. In terms of speech, unfamiliar varieties (such as foreign-accented speech or speech produced in an unfamiliar dialect) are generally less intelligible than speech produced in a variety that matches that of the listener. In terms of the listener, studies have found that listener experience affects intelligibility of unfamiliar varieties of a language. The current study explores the extent to which a listener’s biases toward globalization and immigration predict speech intelligibility. High and low predictability sentences from three men (US English, Scottish English, Mandarin-accented English) were mixed with background noise. Fifty L1 US English listeners first typed the final word of each sentence and were then asked to answer questions related to their views on globalism and nationalism. As expected, listeners were more accurate in the high compared to low predictability sentences. Surprisingly, the Mandarin-accented speaker was the most intelligible. A follow-up study with duration-normalized samples found the same result. Contrary to expectations, listener responses to the globalist-nationalist survey had no impact on intelligibility. This may suggest that difficulty understanding unfamiliar varieties of a language is not related to listener attitudes.

Many tasks, same outcome: Role of training task on learning and maintenance of noise-vocoded speech.

Listeners who use cochlear implants show variability in speech recognition. Research suggests that structured auditory training can improve speech recognition outcomes in cochlear implant users, and a central goal in the rehabilitation literature is to identify factors that maximize training. Here, we examined factors that may influence perceptual learning for noise-vocoded speech in normal hearing listeners as a foundational step towards clinical recommendations. Three groups of listeners were exposed to anomalous noise-vocoded sentences and completed one of three training tasks: transcription with feedback, transcription without feedback, or talker identification. Listeners completed a word transcription test at three time points: immediately before training, immediately after training, and one week following training. Accuracy at test was indexed by keyword accuracy at the sentence-initial and sentence-final position for high and low predictability noise-vocoded sentences. Following training, listeners showed improved transcription for both sentence-initial and sentence-final items, and for both low and high predictability sentences. The training groups showed robust and equivalent learning of noise-vocoded sentences immediately after training. Critically, gains were largely maintained equivalently among training groups one week later. These results converge with evidence pointing towards the utility of non-traditional training tasks to maximize perceptual learning of noise-vocoded speech.

Semantic Predictability Facilitates Comprehension of Degraded Speech in a Graded Manner.

Previous studies have shown that at moderate levels of spectral degradation, semantic predictability facilitates language comprehension. It is argued that when speech is degraded, listeners have narrowed expectations about the sentence endings; i.e., semantic prediction may be limited to only most highly predictable sentence completions. The main objectives of this study were to (i) examine whether listeners form narrowed expectations or whether they form predictions across a wide range of probable sentence endings, (ii) assess whether the facilitatory effect of semantic predictability is modulated by perceptual adaptation to degraded speech, and (iii) use and establish a sensitive metric for the measurement of language comprehension. For this, we created 360 German Subject-Verb-Object sentences that varied in semantic predictability of a sentence-final target word in a graded manner (high, medium, and low) and levels of spectral degradation (1, 4, 6, and 8 channels noise-vocoding). These sentences were presented auditorily to two groups: One group (n =48) performed a listening task in an unpredictable channel context in which the degraded speech levels were randomized, while the other group (n =50) performed the task in a predictable channel context in which the degraded speech levels were blocked. The results showed that at 4 channels noise-vocoding, response accuracy was higher in high-predictability sentences than in the medium-predictability sentences, which in turn was higher than in the low-predictability sentences. This suggests that, in contrast to the narrowed expectations view, comprehension of moderately degraded speech, ranging from low- to high- including medium-predictability sentences, is facilitated in a graded manner; listeners probabilistically preactivate upcoming words from a wide range of semantic space, not limiting only to highly probable sentence endings. Additionally, in both channel contexts, we did not observe learning effects; i.e., response accuracy did not increase over the course of experiment, and response accuracy was higher in the predictable than in the unpredictable channel context. We speculate from these observations that when there is no trial-by-trial variation of the levels of speech degradation, listeners adapt to speech quality at a long timescale; however, when there is a trial-by-trial variation of the high-level semantic feature (e.g., sentence predictability), listeners do not adapt to low-level perceptual property (e.g., speech quality) at a short timescale.

Effects of Contextual Predictability Clues in Speech Materials on the Korean Speech Intelligibility Index

Purpose: This study aimed to derive band-importance functions (BIFs) and transfer functions (TFs) according to contextual predictability clues to determine the influence of contextual predictability clues in Korean speech material on the speech intelligibility index (SII). Methods: This study was conducted on 156 native speakers of Korean who had normal hearing. Korean speech perception in noise test material, which was composed of 120 high-predictability and 120 low-predictability sentences, was used for stimuli. To obtain intelligibility data, participants were tested for intelligibility in various frequency ranges and signal-to-noise ratio conditions. In order to derive the BIF and the TF, a nonlinear optimization procedure using MATLAB (MathWorks, Inc.) was used. Results: The BIF derived from the high-predictability sentences showed a peak in areas of 700 Hz (7.0%), 1,850 Hz (8.5%), and 4,800 Hz (7.6%). The crossover frequency for the high-predictability sentences was around 1,370 Hz. The BIF derived from the low-predictability sentences showed a peak in areas of 570 Hz (7.5%), 1,850 Hz (9.3%), and 4,000 Hz (8.0%). The crossover frequency for the low-predictability sentences was around 1,600 Hz. In the case of the TF, the TF curves derived from high-predictability sentences were steeper than those derived from low-predictability sentences.Conclusion: In the SII model, speech intelligibility differs according to contextual predictability clues. Especially, the more contextual predictability clues at the identical audibility, the higher the intelligibility predicted by the SII. Therefore, accurate speech intelligibility prediction requires the use of SII considering the contextual predictability clues that are characteristic of the stimulus.

Bilateral cochlear implantation versus unilateral cochlear implantation in deaf children: Effects of sentence context and listening conditions on recognition of spoken words in sentences

ObjectivesPrevious studies have investigated the efficacy of bilateral cochlear implants (CIs) in deaf children. The current study focused on the use of sentence-context information in different listening conditions to better explain the benefits of bilateral cochlear implantation. We compared the word recognition abilities of children with bilateral CIs and children with unilateral CIs in relation to sentence context and listening conditions. Additionally, we investigated whether sentence context- and listening condition-dependent word recognition scores can differentiate children with bilateral CIs from children with unilateral CIs. MethodsTwenty children with bilateral CIs and 20 children with unilateral CIs participated in this study. All children were presented with semantically controlled sentences (high vs. low predictability) in quiet and noisy conditions and were asked to repeat the final words of each sentence. ResultsChildren with bilateral CIs had significantly higher word recognition scores than children with unilateral CIs on words embedded in both high- and low-predictability sentences in noisy conditions. The two groups recognized more words in high-predictability sentences than in low-predictability sentences in noisy conditions. The scores on the high-predictability sentences in noisy conditions significantly differentiated children with bilateral CIs from children with unilateral CIs. ConclusionBilateral cochlear implantation is more advantageous than unilateral cochlear implantation at the auditory-linguistic processing level in complex listening conditions.

The role of semantic predictability in adaptation to non-native-accented speech

Non-native-accented speech is more difficult for native listeners to understand than native-accented speech. However, listeners can improve their abilities to understand nonnative—accented speech through exposure and training. The goal of this project is to explore whether exposing native listeners to different sentence types affects listeners' adaptation to non-native speech. Listeners will be trained on high predictability sentences (e.g., “The color of a lemon is yellow”), low predictability sentences (e.g., “Mom said that it is yellow”), or semantically anomalous sentences (e.g., “The green week did the page”). Previous research has demonstrated that semantic predictability impacts speech perception, but its influence on adaptation to nonnative speech is unknown. Will training with low predictability or anomalous stimuli require listeners to focus more attention on the acoustic-phonetic properties of the accent and thus lead to greater adaptation and generalizable learning? Or will training with high predictability stimuli provide valuable semantic information that will allow listeners to create a better framework for improving perception? The data from this experiment will shed light on perceptual mechanisms, including how semantic predictability interacts with adaptation and learning.Non-native-accented speech is more difficult for native listeners to understand than native-accented speech. However, listeners can improve their abilities to understand nonnative—accented speech through exposure and training. The goal of this project is to explore whether exposing native listeners to different sentence types affects listeners' adaptation to non-native speech. Listeners will be trained on high predictability sentences (e.g., “The color of a lemon is yellow”), low predictability sentences (e.g., “Mom said that it is yellow”), or semantically anomalous sentences (e.g., “The green week did the page”). Previous research has demonstrated that semantic predictability impacts speech perception, but its influence on adaptation to nonnative speech is unknown. Will training with low predictability or anomalous stimuli require listeners to focus more attention on the acoustic-phonetic properties of the accent and thus lead to greater adaptation and generalizable learning? Or will training with high ...

Semantic predictability and the use of creaky voice in female speakers

The purpose of this study was to investigate the prevalence of creaky voice in sentence-final position as a function of semantic predictability of the final word. Creaky voice is maligned in the media and often claimed to be less intelligible than normal phonation. A recent study finds some evidence to support this claim by examining intelligibility of single words. If speakers were concerned about intelligibility of their speech, they may be less likely to use it in sentences with little semantic support (e.g., “Mr. Black knew about the pad” compared to “Tear off some paper from the pad”). In the current study, 11 young female speakers without any vocal pathologies produced sentences from the Speech Perception in Noise (SPIN) test. Fourteen final words that appeared in both high and low semantic predictability sentences were selected for analysis. Three outcome measures were examined for these final words: presence versus absence of creaky voice, duration of creaky voice, and type of creaky voice. Contrary to our expectations, the results indicated that semantic support does not significantly predict the existence, amount, or type of creaky voice in young female speakers.

Influence of speaking style adaptations and semantic context on the time course of word recognition in quiet and in noise

This study examines the effects of different listener-oriented speaking styles and semantic contexts on online spoken word recognition using eyetracking. In Experiment 1, different groups of listeners participated in a word-identification-in-noise and in a pleasantness-rating task. Listeners heard sentences with high- versus low-predictability semantic contexts produced in infant-directed speech, Clear Speech, and Conversational Speech. Experiment 2 (in silence) and 3 (in noise) investigated the time course of visual fixations to target objects when participants were listening to different speaking styles and contexts. Results from all experiments show that relative to conversational speech, both infant-directed speech and Clear Speech improved word recognition for high-predictability sentences, in quiet as well as in noise. This indicates that established advantages of infant-directed speech for young listeners cannot be attributed only to affect; the acoustic enhancements in infant-directed speech benefit adult speech processing as well. Furthermore, in silence (Experiment 2) lexical access was facilitated by contextual cues even in conversational speech; but in noise (Experiment 3) listeners reliably focused the target only when a combination of contextual cues and listener-adapted acoustic–phonetic cues were available. These findings suggest that both semantic cues and listener-oriented acoustic enhancements are needed to facilitate word recognition, especially in adverse listening conditions.

Listening effort during speech perception enhances auditory and lexical processing for non-native listeners and accents

Speech communication in a non-native language (L2) can feel effortful, and the present study suggests that this effort affects both auditory and lexical processing. EEG recordings (electroencephalography) were made from native English (L1) and Korean listeners while they listened to English sentences spoken with two accents (English and Korean) in the presence of a distracting talker. Neural entrainment (i.e., phase locking between the EEG recording and the speech amplitude envelope) was measured for target and distractor talkers. L2 listeners had relatively greater entrainment for target talkers than did L1 listeners, likely because their difficulty with L2 speech recognition caused them to focus more attention on the speech signal. N400 was measured for the final word in each sentence, and L2 listeners had greater lexical processing in high-predictability sentences than did L1 listeners. L1 listeners had greater target-talker entrainment when listening to the more difficult L2 accent than their own L1 accent, and similarly had larger N400 responses for the L2 accent. It thus appears that the increased effort of L2 listeners, as well as L1 listeners understanding L2 speech, modulates their auditory and lexical processing during speech recognition. This may provide a mechanism to compensate for their perceptual challenges under adverse conditions.

Extrinsic Cognitive Load Impairs Spoken Word Recognition in High- and Low-Predictability Sentences.

Listening effort (LE) induced by speech degradation reduces performance on concurrent cognitive tasks. However, a converse effect of extrinsic cognitive load on recognition of spoken words in sentences has not been shown. The aims of the present study were to (a) examine the impact of extrinsic cognitive load on spoken word recognition in a sentence recognition task and (b) determine whether cognitive load and/or LE needed to understand spectrally degraded speech would differentially affect word recognition in high- and low-predictability sentences. Downstream effects of speech degradation and sentence predictability on the cognitive load task were also examined. One hundred twenty young adults identified sentence-final spoken words in high- and low-predictability Speech Perception in Noise sentences. Cognitive load consisted of a preload of short (low-load) or long (high-load) sequences of digits, presented visually before each spoken sentence and reported either before or after identification of the sentence-final word. LE was varied by spectrally degrading sentences with four-, six-, or eight-channel noise vocoding. Level of spectral degradation and order of report (digits first or words first) were between-participants variables. Effects of cognitive load, sentence predictability, and speech degradation on accuracy of sentence-final word identification as well as recall of preload digit sequences were examined. In addition to anticipated main effects of sentence predictability and spectral degradation on word recognition, we found an effect of cognitive load, such that words were identified more accurately under low load than high load. However, load differentially affected word identification in high- and low-predictability sentences depending on the level of sentence degradation. Under severe spectral degradation (four-channel vocoding), the effect of cognitive load on word identification was present for high-predictability sentences but not for low-predictability sentences. Under mild spectral degradation (eight-channel vocoding), the effect of load was present for low-predictability sentences but not for high-predictability sentences. There were also reliable downstream effects of speech degradation and sentence predictability on recall of the preload digit sequences. Long digit sequences were more easily recalled following spoken sentences that were less spectrally degraded. When digits were reported after identification of sentence-final words, short digit sequences were recalled more accurately when the spoken sentences were predictable. Extrinsic cognitive load can impair recognition of spectrally degraded spoken words in a sentence recognition task. Cognitive load affected word identification in both high- and low-predictability sentences, suggesting that load may impact both context use and lower-level perceptual processes. Consistent with prior work, LE also had downstream effects on memory for visual digit sequences. Results support the proposal that extrinsic cognitive load and LE induced by signal degradation both draw on a central, limited pool of cognitive resources that is used to recognize spoken words in sentences under adverse listening conditions.

Interaction of cognitive load, sentence predictability, and speech degradation in spoken word recognition and memory

Whether cognitive load and/or listening effort needed to understand degraded speech differentially affect bottom-up and top-down processes is not well understood. The current project examined effects of sentence predictability, speech degradation, and cognitive load on the recognition of sentence-final words and on the recall of short (low-load) or long (high-load) sequences of visual digits presented prior to each spoken sentence. In addition to main effects of sentence predictability and spectral degradation, word recognition in both high- and low-predictability sentences was modulated by cognitive load when accuracy was between 35 and 80 percent. Words were identified more accurately under low load than high load. Digit recall was affected by load, speech degradation, and sentence predictability. Results indicate that cognitive load affects processes used to identify words in both low- and high-predictability sentences, and that listening effort affects memory for visual digits.

Relative Weighting of Semantic and Syntactic Cues in Native and Non-Native Listeners' Recognition of English Sentences.

Non-native listeners do not recognize English sentences as effectively as native listeners, especially in noise. It is not entirely clear to what extent such group differences arise from differences in relative weight of semantic versus syntactic cues. This study quantified the use and weighting of these contextual cues via Boothroyd and Nittrouer's j and k factors. The j represents the probability of recognizing sentences with or without context, whereas the k represents the degree to which context improves recognition performance. Four groups of 13 normal-hearing young adult listeners participated. One group consisted of native English monolingual (EMN) listeners, whereas the other three consisted of non-native listeners contrasting in their language dominance and first language: English-dominant Russian-English, Russian-dominant Russian-English, and Spanish-dominant Spanish-English bilinguals. All listeners were presented three sets of four-word sentences: high-predictability sentences included both semantic and syntactic cues, low-predictability sentences included syntactic cues only, and zero-predictability sentences included neither semantic nor syntactic cues. Sentences were presented at 65 dB SPL binaurally in the presence of speech-spectrum noise at +3 dB SNR. Listeners orally repeated each sentence and recognition was calculated for individual words as well as the sentence as a whole. Comparable j values across groups for high-predictability, low-predictability, and zero-predictability sentences suggested that all listeners, native and non-native, utilized contextual cues to recognize English sentences. Analysis of the k factor indicated that non-native listeners took advantage of syntax as effectively as EMN listeners. However, only English-dominant bilinguals utilized semantics to the same extent as EMN listeners; semantics did not provide a significant benefit for the two non-English-dominant groups. When combined, semantics and syntax benefitted EMN listeners significantly more than all three non-native groups of listeners. Language background influenced the use and weighting of semantic and syntactic cues in a complex manner. A native language advantage existed in the effective use of both cues combined. A language-dominance effect was seen in the use of semantics. No first-language effect was present for the use of either or both cues. For all non-native listeners, syntax contributed significantly more to sentence recognition than semantics, possibly due to the fact that semantics develops more gradually than syntax in second-language acquisition. The present study provides evidence that Boothroyd and Nittrouer's j and k factors can be successfully used to quantify the effectiveness of contextual cue use in clinically relevant, linguistically diverse populations.

The Contribution of Auditory and Cognitive Factors to Intelligibility of Words and Sentences in Noise.

Understanding the causes for speech-in-noise (SiN) perception difficulties is complex, and is made even more difficult by the fact that listening situations can vary widely in target and background sounds. While there is general agreement that both auditory and cognitive factors are important, their exact relationship to SiN perception across various listening situations remains unclear. This study manipulated the characteristics of the listening situation in two ways: first, target stimuli were either isolated words, or words heard in the context of low- (LP) and high-predictability (HP) sentences; second, the background sound, speech-modulated noise, was presented at two signal-to-noise ratios. Speech intelligibility was measured for 30 older listeners (aged 62-84) with age-normal hearing and related to individual differences in cognition (working memory, inhibition and linguistic skills) and hearing (PTA(0.25-8 kHz) and temporal processing). The results showed that while the effect of hearing thresholds on intelligibility was rather uniform, the influence of cognitive abilities was more specific to a certain listening situation. By revealing a complex picture of relationships between intelligibility and cognition, these results may help us understand some of the inconsistencies in the literature as regards cognitive contributions to speech perception.

Effects of speaking style and context on online word recognition in adverse listening conditions

This study investigated the time-course of word recognition in adverse listening conditions. Specifically, we examined the effect of different listener-oriented speaking styles and semantic context on lexical access in quiet and in noise. Young adult listeners participated in an online visual word recognition experiment. They heard sentences with a high- versus low-predictability semantic context, produced in Conversational (CO), Infant-Directed (IDS), and Clear (CS) speech while fixating two pictures on a screen: a target that matched the last word of the auditory stimulus and a distractor. All sentences were presented either in quiet, or mixed with speech-shaped noise at a −5 dB SNR. Results showed that IDS provided similar perceptual benefits to adult listeners as CS. Relative to low-predictability CO baseline, IDS and CS increased speed of word recognition for high-predictability sentences, in quiet and in noise equally. However, in the quiet condition, lexical access was eventually facilitated by contextual cues even in CO, but listeners in noise reliably focused the target only when a combination of contextual cues and exaggerated acoustic-phonetic cues was available. These findings suggest that both semantic cues and listener-oriented acoustic enhancements are needed for reliable and rapid lexical access, especially in adverse conditions.

The Effects of Linguistic Context on Word Recognition in Noise by Elderly Listeners Using Spanish Sentence Lists (SSL).

This study evaluated the effects of the linguistic context on the recognition of words in noise in older listeners using the Spanish Sentence Lists. These sentences were developed based on the approach of the SPIN test for the English language, which contains high and low predictability (HP and LP) sentences. In addition, the relative contribution of peripheral hearing sensitivity, measured by pure-tone hearing thresholds (PTA), to the performance on both types of sentences was assessed in a regression analysis. The results showed that older listeners obtained benefits on word recognition from the linguistic context. PTA contributed significantly to explaining the variance in performance on both HP and LP sentences.

Elaboración de una versión reducida de las listas de frases en español (vr-LFE) para evaluar la percepción del habla con ruido

This article presents, a short version of the ‘listas de frases en español’ (vr-LFE; “Lists of Phrases in Spanish”) to evaluate speech perception in noise. The original version is an adaptation of the SPIN (Speech Perception in Noise) test for the English language. The original LFE consists of 6 lists, each of them including 25 high-predictability sentences and 25 low-predictability sentences. The difference between the correct recognition scores on the two types of sentences provides an estimation of the effective use of linguistic context (semantic, syntactic, and pragmatic information) by the listener in the speech perception process. In the present work, 60 sentences were selected from an initial pool of 300 sentences. These 60 sentences were arranged in 5 lists of 12 sentences each (6 high-predictability and 6 low-predictability sentences). This version preserves the same characteristics of reliability (equivalence among the lists) and validity (sensibility to the effects of sentence context and to the signal-to-noise ratio) as the original version, but considerably reduces the time needed for its administration. These lists can be used to evaluate speech perception difficulties in noise in older listeners with mild-to-moderate hearing loss (presbycusis), with or without mild cognitive impairment, and in non-native listeners with different degrees of linguistic competence.

Acoustic and Semantic Enhancements for Children With Cochlear Implants

In this study, the authors examined how signal clarity interacts with the use of sentence context information in determining speech-in-noise recognition for children with cochlear implants and children with normal hearing. One hundred and twenty sentences in which the final word varied in predictability (high vs. low semantic context) were produced in conversational and clear speech. Nine children with cochlear implants and 9 children with normal hearing completed the sentence-in-noise listening tests and a standardized language measure. Word recognition in noise improved significantly for both groups of children for high-predictability sentences in clear speech. Children with normal hearing benefited more from each source of information compared with children with cochlear implants. There was a significant correlation between more developed language skills and the ability to use contextual enhancements. The smaller context gain in clear speech for children with cochlear implants is in accord with the effortfulness hypothesis (McCoy et al., 2005) and points to the cumulative effects of noise throughout the processing system. Modifications of the speech signal and the context of the utterances through changes in the talker output hold substantial promise as a communication enhancement technique for both children with cochlear implants and children with normal hearing.

The Revised Speech Perception in Noise Test (R-SPIN) in a Multiple Signal-to-Noise Ratio Paradigm

The Revised Speech Perception in Noise Test (R-SPIN; Bilger, 1984b) is composed of 200 target words distributed as the last words in 200 low-predictability (LP) and 200 high-predictability (HP) sentences. Four list pairs, each consisting of two 50-sentence lists, were constructed with the target word in a LP and HP sentence. Traditionally the R-SPIN is presented at a signal-to-noise ratio (SNR, S/N) of 8 dB with the listener task to repeat the last word in the sentence. The purpose was to determine the practicality of altering the R-SPIN format from a single SNR paradigm into a multiple SNR paradigm from which the 50% points for the HP and LP sentences can be calculated. Three repeated measures experiments were conducted. Forty listeners with normal hearing and 184 older listeners with pure-tone hearing loss participated in the sequence of experiments. The R-SPIN sentences were edited digitally (1) to maintain the temporal relation between the sentences and babble, (2) to establish the SNRs, and (3) to mix the speech and noise signals to obtain SNRs between -1 and 23 dB. All materials were recorded on CD and were presented through an earphone with the responses recorded and analyzed at the token level. For reference purposes the Words-in-Noise Test (WIN) was included in the first experiment. In Experiment 1, recognition performances by listeners with normal hearing were better than performances by listeners with hearing loss. For both groups, performances on the HP materials were better than performances on the LP materials. Performances on the LP materials and on the WIN were similar. Performances at 8 dB S/N were the same with the traditional fixed level presentation and the descending presentation level paradigms. The results from Experiment 2 demonstrated that the four list pairs of R-SPIN materials produced good first approximation psychometric functions over the -4 to 23 dB S/N range, but there were irregularities. The data from Experiment 2 were used in Experiment 3 to guide the selection of the words to be used at the various SNRs that would provide homogeneous performances at each SNR and would produce systematic psychometric functions. In Experiment 3, the 50% points were in good agreement for the LP and HP conditions within both groups of listeners. The psychometric functions for List Pairs 1 and 2, 3 and 4, and 5 and 6 had similar characteristics and maintained reasonable separations between the HP and LP functions, whereas the HP and LP functions for List Pair 7 and 8 bisected one another at the lower SNRs. This study indicates that the R-SPIN can be configured into a multiple SNR paradigm. A more in-depth study with the R-SPIN materials is needed to develop lists that are systematic and reasonably equivalent for use on listeners with hearing loss. The approach should be based on the psychometric characteristics of the 200 HP and 200 LP sentences with the current R-SPIN lists discarded. Of importance is maintaining the synchrony between the sentences and their accompanying babble.

Speech-in-noise measures: Variable versus fixed speech and noise levels

Objective: The purpose was to determine if speech-recognition performances were the same when the speech level was fixed and the noise level varied as when the noise level was fixed and the speech level varied. Design: A descriptive/quasi-experimental experiment was conducted with Lists 3 and 4 of the revised speech perception in noise (R-SPIN) test, which involves high predictability (HP) and low predictability (LP) words. The R-SPIN was modified into a multiple signal-to-noise paradigm (23- to −1-dB in 3-dB decrements) from which the 50% points were calculated with the Spearman-Kärber equation. Study sample: Sixteen young listeners with normal hearing and 48 older listeners with pure-tone hearing losses participated. Results: The listeners with normal hearing performed better than the listeners with hearing loss on both the HP and LP conditions. For both groups of listeners, (1) performance on the HP sentences was better than on the LP sentences, and (2) the mean 50% points were 0.1 to 0.4 dB lower (better) on the speech-variable, babble-fixed condition than on the speech-fixed, babble-variable condition. Conclusions: For practical purposes the ≤ 0.4-dB differences are not considered noteworthy as the differences are smaller than the decibel value of one word on the test (0.6 dB).

Effects of age and hearing loss on the recognition of interrupted words in isolation and in sentences

The ability to recognize spoken words interrupted by silence was investigated with young normal-hearing listeners and older listeners with and without hearing impairment. Target words from the revised SPIN test by Bilger et al. [J. Speech Hear. Res. 27(1), 32-48 (1984)] were presented in isolation and in the original sentence context using a range of interruption patterns in which portions of speech were replaced with silence. The number of auditory "glimpses" of speech and the glimpse proportion (total duration glimpsed/word duration) were varied using a subset of the SPIN target words that ranged in duration from 300 to 600 ms. The words were presented in isolation, in the context of low-predictability (LP) sentences, and in high-predictability (HP) sentences. The glimpse proportion was found to have a strong influence on word recognition, with relatively little influence of the number of glimpses, glimpse duration, or glimpse rate. Although older listeners tended to recognize fewer interrupted words, there was considerable overlap in recognition scores across listener groups in all conditions, and all groups were affected by interruption parameters and context in much the same way.