Signing Exact English Transliteration: Effects of Accuracy and Lag Time on Message Intelligibility.

This paper, the fourth in a series concerned with the level of access afforded to students who use educational interpreters, focuses on the intelligibility of interpreters who use Signing Exact English (SEE). Eight expert receivers of SEE were employed to evaluate the intelligibility of transliterated messages that varied in accuracy and lag time. Results of intelligibility tests showed that, similar to Cued Speech transliterators, (a) accuracy had a large positive effect on transliterator intelligibility, (b) overall intelligibility (69%) was higher than average accuracy (58%), and (c) the likelihood that an utterance reached 70% intelligibility was somewhat sigmoidal in shape, with the likelihood of reaching 70% intelligibility dropping off fastest for accuracy values <65%. Accuracy alone accounted for 53% of the variance in transliterator intelligibility; mouthing was identified as a secondary factor that explained an additional 11%. Although lag time accounted for just .4% of the remaining variance, utterances produced with lag times between .6 and 1.2 s were most likely to exceed 70% intelligibility. With 36% of the variance still unexplained, other sources of transliterator variability (for example, facial expression, nonmanual markers, and mouth/sign synchronization) may also play a role in intelligibility and should be explored in future research.

Speaking Clearly for Older Adults With Normal Hearing: The Role of Speaking Rate.

Purpose Talkers typically use a slow speaking rate when producing clear speech, a speaking style that has been widely shown to improve intelligibility over conversational speech in difficult communication environments. With training, however, talkers can learn to produce a form of clear speech at normal speaking rates that provides young listeners with normal hearing much of the same intelligibility benefit. The purpose of this study was to determine if older listeners with normal hearing can also obtain an intelligibility benefit from clear speech at normal rates. Method Eight older listeners (55-68 years of age) with normal hearing were presented with nonsense sentences from 4 talkers in a background of speech-shaped noise (signal-to-noise ratio = 0 dB). Intelligibility (percent correct key words) was evaluated for conversational and clear speech produced at 2 speaking rates (normal and slow), for a total of 4 conditions: conv/normal, conv/slow, clear/normal, and clear/slow. Results As expected, the clear/slow speaking condition provided a large and robust intelligibility advantage (23 points) over conv/normal speech. The conv/slow condition provided almost as much benefit on average (21 points) but was highly variable across talkers. Notably, the clear/normal speaking condition provided the same size intelligibility advantage (14 points), previously reported for young listeners with normal hearing (Krause & Braida, 2002), thus extending the benefit of clear speech at normal speaking rates to older normal-hearing listeners. Conclusions Applications based on clear/normal speech (e.g., signal processing approaches for hearing aids) have the potential to provide comparable intelligibility improvements to older and younger listeners alike.

Signing Exact English Transliteration: Effects of Speaking Rate and Lag Time on Production Accuracy.

This paper is the third in a series concerned with the level of access provided to deaf and hard of hearing children who rely on interpreters to access classroom communication. The first two papers focused on the accuracy and intelligibility of educational interpreters who use Cued Speech (CS); this study examines the accuracy of those who use Signing Exact English (SEE). Accuracy, or the proportion of the message correctly produced by the interpreter, was evaluated in 12 SEE transliterators with varying degrees of experience at three different speaking rates (slow, normal, and fast). Results were similar to those previously reported for CS transliterators: (a) speaking rate had a large negative effect on accuracy, primarily due to increased frequency of omissions, (b) the effect of lag time on accuracy was also negative, but relatively small, accounting for just 8% of the variance, and (c) highly experienced transliterators were somewhat more accurate than transliterators with minimal experience, although experience alone did not guarantee accuracy. Lastly, like their CS counterparts, the overall accuracy of the 12 SEE transliterators, 42% on average, was low enough to raise serious concerns about the quality of transliteration services that (at least some) children receive in educational settings.

Cued Speech Transliteration: Effects of Accuracy and Lag Time on Message Intelligibility.

This paper is the second in a series concerned with the level of access afforded to students who use educational interpreters. The first paper (Krause & Tessler, 2016) focused on factors affecting accuracy of messages produced by Cued Speech (CS) transliterators (expression). In this study, factors affecting intelligibility (reception by deaf consumers) of those messages is explored. Results for eight highly skilled receivers of CS showed that (a) overall intelligibility (72%) was higher than average accuracy (61%), (b) accuracy had a large positive effect on intelligibility, accounting for 26% of the variance, and (c) the likelihood that an utterance reached 70% intelligibility as a function of accuracy was sigmoidal, decreasing sharply for accuracy values below 65%. While no direct effect of lag time on intelligibility could be detected, intelligibility was most likely to exceed 70% for utterances produced with lag times between 0.6 and 1.8 s. Differences between CS transliterators suggested sources of transliterator variability (e.g. speechreadability, facial expression, non-manual markers, cueing rate) that are also likely to affect intelligibility and thus warrant further investigation. Such research, along with investigations of other communication options (e.g. American Sign Language, signed English systems, etc.) are important for ensuring accessibility to all students who use educational interpreters.

Cued Speech Transliteration: Effects of Speaking Rate and Lag Time on Production Accuracy.

Many deaf and hard-of-hearing children rely on interpreters to access classroom communication. Although the exact level of access provided by interpreters in these settings is unknown, it is likely to depend heavily on interpreter accuracy (portion of message correctly produced by the interpreter) and the factors that govern interpreter accuracy. In this study, the accuracy of 12 Cued Speech (CS) transliterators with varying degrees of experience was examined at three different speaking rates (slow, normal, fast). Accuracy was measured with a high-resolution, objective metric in order to facilitate quantitative analyses of the effect of each factor on accuracy. Results showed that speaking rate had a large negative effect on accuracy, caused primarily by an increase in omitted cues, whereas the effect of lag time on accuracy, also negative, was quite small and explained just 3% of the variance. Increased experience level was generally associated with increased accuracy; however, high levels of experience did not guarantee high levels of accuracy. Finally, the overall accuracy of the 12 transliterators, 54% on average across all three factors, was low enough to raise serious concerns about the quality of CS transliteration services that (at least some) children receive in educational settings.

A Method for Transcribing the Manual Components of Cued Speech.

Designed to allow visual communication of speech signals, Cued Speech consists of discrete hand signals that are produced in synchrony with the visual mouth movements of speech. The purpose of this paper is to describe a method for transcribing these hand signals. Procedures are presented for identifying 1) the steady-state portion of the cue to be analyzed, 2) the cue's handshape, and 3) the cue's placement. Reliability is evaluated, using materials from 12 cuers that were transcribed on two separate occasions (either by the original rater or a second rater). Results show very good intra-rater and inter-rater reliability on average, which remained good across a variety of individual cuers, even when the cuer's hand gestures were heavily coarticulated. Given its high reliability, this transcription method may be of benefit to applications that require systematic and quantitative analysis of Cued Speech production in various populations. In addition, some of the transcription principles from this method may be helpful in improving accuracy of automatic Cued Speech recognition systems.

An adaptive clinical test of temporal resolution: within-channel and across-channel gap detection.

OBJECTIVE: Several methods exist to measure temporal resolution in a clinical setting. The Adaptive Tests of Temporal Resolution (ATTR©) are unique in that they incorporate an adaptive psychophysical procedure to present stimuli via computer sound card. The purpose of this study was to determine if ATTR gap detection thresholds (GDTs) were stable across presentation levels (80 dB SPL, listener-selected level) and sound cards (high-end, inexpensive). DESIGN: GDTs were measured using three conditions of the ATTR: broad-band noise within-channel (BBN-WC), narrowband noise within-channel (NBN-WC), and narrowband noise across-channel (NBN-AC). Analysis of the acoustical properties of ATTR stimuli was made by measuring the electrical signals produced by each sound card. STUDY SAMPLE: Participants were 30 young adults with normal hearing. RESULTS: The ATTR GDTs did not differ between presentation levels for all three stimulus conditions. Also, neither ATTR stimuli nor ATTR GDTs differed between sound cards for all conditions. CONCLUSIONS: The ATTR may be used in a clinical setting with a relatively inexpensive sound card and listener-selected levels. Normative performance values for each ATTR condition are provided.

Conversational and clear speech intelligibility of /bVd/ syllables produced by native and non-native English speakers.

The ability of native and non-native speakers to enhance intelligibility of target vowels by speaking clearly was compared across three talker groups: monolingual English speakers and native Spanish speakers with either an earlier or a later age of immersion in an English-speaking environment. Talkers produced the target syllables "bead, bid, bayed, bed, bad" and "bod" in 'conversational' and clear speech styles. The stimuli were presented to native English-speaking listeners in multi-talker babble with signal-to-noise ratios of -8 dB for the monolingual and early learners and -4 dB for the later learners. The monolinguals and early learners of English showed a similar average clear speech benefit, and the early learners showed equal or greater intelligibility than monolinguals for most target vowels. The 4-dB difference in signal-to-noise ratio yielded approximately equal average intelligibility for the monolinguals and later learners. The average clear speech benefit was smallest for the later learners, and a significant clear speech decrement was obtained for the target syllable "bid." These results suggest that later learners of English as a second language may be less able than monolinguals to accommodate listeners in noisy environments, due to a reduced ability to improve intelligibility by speaking more clearly.

Evaluating the role of spectral and envelope characteristics in the intelligibility advantage of clear speech.

In adverse listening conditions, talkers can increase their intelligibility by speaking clearly [Picheny, M.A., et al. (1985). J. Speech Hear. Res. 28, 96-103; Payton, K. L., et al. (1994). J. Acoust. Soc. Am. 95, 1581-1592]. This modified speaking style, known as clear speech, is typically spoken more slowly than conversational speech [Picheny, M. A., et al. (1986). J. Speech Hear. Res. 29, 434-446; Uchanski, R. M., et al. (1996). J. Speech Hear. Res. 39, 494-509]. However, talkers can produce clear speech at normal rates (clear/normal speech) with training [Krause, J. C., and Braida, L. D. (2002). J. Acoust. Soc. Am. 112, 2165-2172] suggesting that clear speech has some inherent acoustic properties, independent of rate, that contribute to its improved intelligibility. Identifying these acoustic properties could lead to improved signal processing schemes for hearing aids. Two global-level properties of clear/normal speech that appear likely to be associated with improved intelligibility are increased energy in the 1000-3000-Hz range of long-term spectra and increased modulation depth of low-frequency modulations of the intensity envelope [Krause, J. C., and Braida, L. D. (2004). J. Acoust. Soc. Am. 115, 362-378]. In an attempt to isolate the contributions of these two properties to intelligibility, signal processing transformations were developed to manipulate each of these aspects of conversational speech independently. Results of intelligibility testing with hearing-impaired listeners and normal-hearing listeners in noise suggest that (1) increasing energy between 1000 and 3000 Hz does not fully account for the intelligibility benefit of clear/normal speech, and (2) simple filtering of the intensity envelope is generally detrimental to intelligibility. While other manipulations of the intensity envelope are required to determine conclusively the role of this factor in intelligibility, it is also likely that additional properties important for highly intelligible speech at normal speech at normal rates remain to be identified.

BKB-SIN and ANL predict perceived communication ability in cochlear implant users.

OBJECTIVE: Cochlear implant (CI) users typically report that speech recognition becomes substantially more difficult in the presence of background noise. This perception is consistent with objective measures of speech recognition showing that CI users require more favorable signal-to-noise ratios than normal-hearing (NH) listeners to achieve equivalent speech recognition. However, recent research in hearing aid users suggests that noise tolerance or the "willingness to listen in noise" may also influence perceived communication ability. Therefore, the purpose of this study was to evaluate the extent to which speech recognition in noise and noise tolerance predict perceived communication ability among adult CI users. DESIGN: Twenty adult CI users were evaluated on an objective test of speech recognition in noise (Bamford-Kowal-Bench Sentences in Noise [BKB-SIN] test) and a measure of noise tolerance (Acceptable Noise Level [ANL] test) and completed a self-report measure of communication difficulty (Abbreviated Profile of Hearing Aid Benefit [APHAB]). Relationships between BKB-SIN scores, ANL scores, and aided APHAB scores for the ease of communication, background noise, reverberation, and Global scales were assessed. In addition, BKB-SIN scores and ANL scores for the CI users were compared with scores for a control group of 23 NH listeners. RESULTS: CI users demonstrated substantially poorer BKB-SIN scores than NH listeners, as expected; however, their ANL scores were similar to those for NH listeners. BKB-SIN scores and ANL scores were not systematically related to one another. Each measure accounted for more than one third of the variance in CI users' aided APHAB Global scores; together, the two measures accounted for 72% of that variance. CONCLUSIONS: Both speech recognition in noise and noise tolerance are strongly associated with CI users' self-perceived communication ability. The two measures seem to reflect different factors that influence an individual's communication experience; thus, both may provide useful clinical information. The establishment of formal criteria for BKB-SIN scores and ANL scores that are predictive of excessive communication difficulty may help to identify CI users who could benefit from additional audiologic rehabilitation.

Toward extending the educational interpreter performance assessment to cued speech.

The Educational Interpreter Performance Assessment (EIPA) is as an important research tool for examining the quality of interpreters who use American Sign Language or a sign system in classroom settings, but it is not currently applicable to educational interpreters who use Cued Speech (CS). In order to determine the feasibility of extending the EIPA to include CS, a pilot EIPA test was developed and administered to 24 educational CS interpreters. Fifteen of the interpreters' performances were evaluated two to three times in order to assess reliability. Results show that the instrument has good construct validity and test-retest reliability. Although more interrater reliability data are needed, intrarater reliability was quite high (0.9), suggesting that the pilot test can be rated as reliably as signing versions of the EIPA. Notably, only 48% of interpreters who formally participated in pilot testing performed at a level that could be considered minimally acceptable. In light of similar performance levels previously reported for interpreters who sign (e.g., Schick, Williams, & Kupermintz, 2006), these results suggest that interpreting services for deaf and hard-of hearing students, regardless of the communication option used, are often inadequate and could seriously hinder access to the classroom environment.

Acoustic properties of naturally produced clear speech at normal speaking rates.

Sentences spoken "clearly" are significantly more intelligible than those spoken "conversationally" for hearing-impaired listeners in a variety of backgrounds [Picheny et al., J. Speech Hear. Res. 28, 96-103 (1985); Uchanski et al., ibid. 39, 494-509 (1996); Payton et al., J. Acoust. Soc. Am. 95, 1581-1592 (1994)]. While producing clear speech, however, talkers often reduce their speaking rate significantly [Picheny et al., J. Speech Hear. Res. 29, 434-446 (1986); Uchanski et al., ibid. 39, 494-509 (1996)]. Yet speaking slowly is not solely responsible for the intelligibility benefit of clear speech (over conversational speech), since a recent study [Krause and Braida, J. Acoust. Soc. Am. 112, 2165-2172 (2002)] showed that talkers can produce clear speech at normal rates with training. This finding suggests that clear speech has inherent acoustic properties, independent of rate, that contribute to improved intelligibility. Identifying these acoustic properties could lead to improved signal processing schemes for hearing aids. To gain insight into these acoustical properties, conversational and clear speech produced at normal speaking rates were analyzed at three levels of detail (global, phonological, and phonetic). Although results suggest that talkers may have employed different strategies to achieve clear speech at normal rates, two global-level properties were identified that appear likely to be linked to the improvements in intelligibility provided by clear/normal speech: increased energy in the 1000-3000-Hz range of long-term spectra and increased modulation depth of low frequency modulations of the intensity envelope. Other phonological and phonetic differences associated with clear/normal speech include changes in (1) frequency of stop burst releases, (2) VOT of word-initial voiceless stop consonants, and (3) short-term vowel spectra.

Investigating alternative forms of clear speech: the effects of speaking rate and speaking mode on intelligibility.

Sentences spoken "clearly" (and slowly) are significantly more intelligible than those spoken "conversationally" for hearing-impaired listeners in a variety of backgrounds [Picheny, Durlach, and Braida, J. Speech Hear. Res. 28, 96-103 (1985); Uchanski et al., J. Speech Hear. Res. 39, 494-509 (1996); Payton, Uchanski, and Braida, J. Acoust. Soc. Am. 95, 1581-1592 (1994)]. However, it is unknown whether slower speaking rates are necessary for highly intelligible speech or whether an alternative form of clear speech exists at faster (i.e., normal) rates. To investigate this question, talkers with significant public speaking experience were asked to produce clear and conversational speech at slow, normal, and quick rates. A method for eliciting clear speech was introduced that ensured the clearest possible speech was obtained at each of these speaking rates. To probe for other highly intelligible speaking modes, talkers also recorded sentences in two other speaking modes: soft and loud. Intelligibility tests indicated that clear speech was the only speaking mode that provided a consistent intelligibility advantage over conversational speech. Moreover, the advantage of clear speech was extended to faster speaking rates than previously reported. These results suggest that clear speech has some inherent acoustic properties that contribute to its high intelligibility without altering rate. Identifying these acoustic properties could lead to improved signal-processing schemes for hearing aids.