Recognition Of Words In Sentences Research Articles

The possible role of early-stage phase-locked neural activities in speech-in-noise perception in human adults across age and hearing loss

Ageing affects auditory neural phase-locked activities which could increase the challenges experienced during speech-in-noise (SiN) perception by older adults. However, evidence for how ageing affects SiN perception through these phase-locked activities is still lacking. It is also unclear whether influences of ageing on phase-locked activities in response to different acoustic properties have similar or different mechanisms to affect SiN perception. The present study addressed these issues by measuring early-stage phase-locked encoding of speech under quiet and noisy backgrounds (speech-shaped noise (SSN) and multi-talker babbles) in adults across a wide age range (19–75 years old). Participants passively listened to a repeated vowel whilst the frequency-following response (FFR) to fundamental frequency that has primary subcortical sources and cortical phase-locked response to slowly-fluctuating acoustic envelopes were recorded. We studied how these activities are affected by age and age-related hearing loss and how they are related to SiN performances (word recognition in sentences in noise). First, we found that the effects of age and hearing loss differ for the FFR and slow-envelope phase-locking. FFR was significantly decreased with age and high-frequency (≥ 2 kHz) hearing loss but increased with low-frequency (< 2 kHz) hearing loss, whilst the slow-envelope phase-locking was significantly increased with age and hearing loss across frequencies. Second, potential relationships between the types of phase-locked activities and SiN perception performances were also different. We found that the FFR and slow-envelope phase-locking positively corresponded to SiN performance under multi-talker babbles and SSN, respectively. Finally, we investigated how age and hearing loss affected SiN perception through phase-locked activities via mediation analyses. We showed that both types of activities significantly mediated the relation between age/hearing loss and SiN perception but in distinct manners. Specifically, FFR decreased with age and high-frequency hearing loss which in turn contributed to poorer SiN performance but increased with low-frequency hearing loss which in turn contributed to better SiN performance under multi-talker babbles. Slow-envelope phase-locking increased with age and hearing loss which in turn contributed to better SiN performance under both SSN and multi-talker babbles. Taken together, the present study provided evidence for distinct neural mechanisms of early-stage auditory phase-locked encoding of different acoustic properties through which ageing affects SiN perception.

Recognising foreign-accented speech of varying intelligibility and linguistic complexity: insights from older listeners with or without hearing loss

Objective The goal of this study was to assess recognition of foreign-accented speech of varying intelligibility and linguistic complexity in older adults. It is important to understand the factors that influence the recognition of this commonly encountered type of speech, in a population that remains understudied in this regard. Design A repeated measures design was used. Listeners repeated back linguistically simple and complex sentences heard in noise. The sentences were produced by three talkers of varying intelligibility: one native American English, one foreign-accented talker of high intelligibility and one foreign-accented talker of low intelligibility. Percentage word recognition in sentences was measured. Study sample Twenty-five older listeners with a range of hearing thresholds participated. Results We found a robust interaction between talker intelligibility and linguistic complexity. Recognition accuracy was higher for simple versus complex sentences, but only for the native and high intelligibility foreign-accented talkers. This pattern was present after effects of working memory capacity and hearing acuity were taken into consideration. Conclusion Older listeners exhibit qualitatively different speech processing strategies for low versus high intelligibility foreign-accented talkers. Differences in recognition accuracy for words presented in simple versus in complex sentence contexts only emerged for speech over a threshold of intelligibility.

Hearing Aid Self-Adjustment: Effects of Formal Speech-Perception Test and Noise.

While listening to recorded sentences with a sound-field level of 65 dB SPL, 24 adults with hearing-aid experience used the “Goldilocks” explore-and-select procedure to adjust level and spectrum of amplified speech to preference. All participants started adjustment from the same generic response. Amplification was provided by a custom-built Master Hearing Aid with online processing of microphone input. Primary goals were to assess the effects of including a formal speech-perception test between repeated self-adjustments and of adding multitalker babble (signal-to-noise ratio +6 dB) during self-adjustment. The speech test did not affect group-mean self-adjusted output, which was close to the National Acoustics Laboratories’ prescription for Non-Linear hearing aids. Individuals, however, showed a wide range of deviations from this prescription. Extreme deviations at the first self-adjustment fell by a small but significant amount at the second. The multitalker babble had negligible effect on group-mean self-selected output but did have predictable effects on word recognition in sentences and on participants’ opinion regarding the most important subjective criterion guiding self-adjustment. Phoneme recognition in monosyllabic words was better with the generic starting response than without amplification and improved further after self-adjustment. The findings continue to support the efficacy of hearing aid self-fitting, at least for level and spectrum. They do not support the need for inclusion of a formal speech-perception test, but they do support the value of completing more than one self-adjustment. Group-mean data did not indicate a need for threshold-based prescription as a starting point for self-adjustment.

The Effect of Hearing Aid Bandwidth and Configuration of Hearing Loss on Bimodal Speech Recognition in Cochlear Implant Users.

(1) To determine the effect of hearing aid (HA) bandwidth on bimodal speech perception in a group of unilateral cochlear implant (CI) patients with diverse degrees and configurations of hearing loss in the nonimplanted ear, (2) to determine whether there are demographic and audiometric characteristics that would help to determine the appropriate HA bandwidth for a bimodal patient. Participants were 33 experienced bimodal device users with postlingual hearing loss. Twenty three of them had better speech perception with the CI than the HA (CI>HA group) and 10 had better speech perception with the HA than the CI (HA>CI group). Word recognition in sentences (AzBio sentences at +10 dB signal to noise ratio presented at 0° azimuth) and in isolation [CNC (consonant-nucleus-consonant) words] was measured in unimodal conditions [CI alone or HAWB, which indicates HA alone in the wideband (WB) condition] and in bimodal conditions (BMWB, BM2k, BM1k, and BM500) as the bandwidth of an actual HA was reduced from WB to 2 kHz, 1 kHz, and 500 Hz. Linear mixed-effect modeling was used to quantify the relationship between speech recognition and listening condition and to assess how audiometric or demographic covariates might influence this relationship in each group. For the CI>HA group, AzBio scores were significantly higher (on average) in all bimodal conditions than in the best unimodal condition (CI alone) and were highest at the BMWB condition. For CNC scores, on the other hand, there was no significant improvement over the CI-alone condition in any of the bimodal conditions. The opposite pattern was observed in the HA>CI group. CNC word scores were significantly higher in the BM2k and BMWB conditions than in the best unimodal condition (HAWB), but none of the bimodal conditions were significantly better than the best unimodal condition for AzBio sentences (and some of the restricted bandwidth conditions were actually worse). Demographic covariates did not interact significantly with bimodal outcomes, but some of the audiometric variables did. For CI>HA participants with a flatter audiometric configuration and better mid-frequency hearing, bimodal AzBio scores were significantly higher than the CI-alone score with the WB setting (BMWB) but not with other bandwidths. In contrast, CI>HA participants with more steeply sloping hearing loss and poorer mid-frequency thresholds (≥82.5 dB) had significantly higher bimodal AzBio scores in all bimodal conditions, and the BMWB did not differ significantly from the restricted bandwidth conditions. HA>CI participants with mild low-frequency hearing loss showed the highest levels of bimodal improvement over the best unimodal condition on CNC words. They were also less affected by HA bandwidth reduction compared with HA>CI participants with poorer low-frequency thresholds. The pattern of bimodal performance as a function of the HA bandwidth was found to be consistent with the degree and configuration of hearing loss for both patients with CI>HA performance and for those with HA>CI performance. Our results support fitting the HA for all bimodal patients with the widest bandwidth consistent with effective audibility.

Nonverbal Reasoning as a Contributor to Sentence Recognition Outcomes in Adults With Cochlear Implants

Significant variability in speech recognition persists among postlingually deafened adults with cochlear implants (CIs). We hypothesize that scores of nonverbal reasoning predict sentence recognition in adult CI users. Cognitive functions contribute to speech recognition outcomes in adults with hearing loss. These functions may be particularly important for CI users who must interpret highly degraded speech signals through their devices. This study used a visual measure of reasoning (the ability to solve novel problems), the Raven's Progressive Matrices (RPM), to predict sentence recognition in CI users. Participants were 39 postlingually deafened adults with CIs and 43 age-matched normal-hearing (NH) controls. CI users were assessed for recognition of words in sentences in quiet, and NH controls listened to eight-channel vocoded versions to simulate the degraded signal delivered by a CI. A computerized visual task of the RPM, requiring participants to identify the correct missing piece in a 3×3 matrix of geometric designs, was also performed. Particular items from the RPM were examined for their associations with sentence recognition abilities, and a subset of items on the RPM was tested for the ability to predict degraded sentence recognition in the NH controls. The overall number of items answered correctly on the 48-item RPM significantly correlated with sentence recognition in CI users (r = 0.35-0.47) and NH controls (r = 0.36-0.57). An abbreviated 12-item version of the RPM was created and performance also correlated with sentence recognition in CI users (r = 0.40-0.48) and NH controls (r = 0.49-0.56). Nonverbal reasoning skills correlated with sentence recognition in both CI and NH subjects. Our findings provide further converging evidence that cognitive factors contribute to speech processing by adult CI users and can help explain variability in outcomes. Our abbreviated version of the RPM may serve as a clinically meaningful assessment for predicting sentence recognition outcomes in CI users.

Development of semantic context facilitation for nonnative-accented speech

Children can use sentence context to facilitate their understanding of both native and nonnative speakers and this benefit increases with age. In this study, 5- to 7-year-old children (n = 90) and adults (n = 30) were compared on their ability to benefit from sentence context. In addition, we examined whether receptive vocabulary accounts for variability in spoken word recognition differently for words spoken in sentences versus in isolation. Stimuli were produced by either native- or nonnative-accented (Japanese and Spanish) speakers. Listeners first identified words in isolation that had been extracted from meaningful sentences. Then they completed the NIH Toolbox Picture Vocabulary Test. Finally, they identified the same spoken words embedded in the original sentences. Children and adults showed significant word recognition advantages for the sentence condition compared to the isolated word condition for both native and nonnative speakers. However, adults showed a much larger benefit from sentence context than the children in the nonnative but not the native condition. Further, older children benefited from context more than younger children. Finally, receptive vocabulary was positively correlated with nonnative recognition of words in sentences but not in isolation for both children and adults, suggesting that better receptive vocabulary enhances use of context for nonnative speech.

Speech Recognition in Adults With Cochlear Implants: The Effects of Working Memory, Phonological Sensitivity, and Aging.

Models of speech recognition suggest that "top-down" linguistic and cognitive functions, such as use of phonotactic constraints and working memory, facilitate recognition under conditions of degradation, such as in noise. The question addressed in this study was what happens to these functions when a listener who has experienced years of hearing loss obtains a cochlear implant. Thirty adults with cochlear implants and 30 age-matched controls with age-normal hearing underwent testing of verbal working memory using digit span and serial recall of words. Phonological capacities were assessed using a lexical decision task and nonword repetition. Recognition of words in sentences in speech-shaped noise was measured. Implant users had only slightly poorer working memory accuracy than did controls and only on serial recall of words; however, phonological sensitivity was highly impaired. Working memory did not facilitate speech recognition in noise for either group. Phonological sensitivity predicted sentence recognition for implant users but not for listeners with normal hearing. Clinical speech recognition outcomes for adult implant users relate to the ability of these users to process phonological information. Results suggest that phonological capacities may serve as potential clinical targets through rehabilitative training. Such novel interventions may be particularly helpful for older adult implant users.

Non-auditory neurocognitive skills contribute to speech recognition in adults with cochlear implants.

ObjectiveUnexplained variability in speech recognition outcomes among postlingually deafened adults with cochlear implants (CIs) is an enormous clinical and research barrier to progress. This variability is only partially explained by patient factors (e.g., duration of deafness) and auditory sensitivity (e.g., spectral and temporal resolution). This study sought to determine whether non‐auditory neurocognitive skills could explain speech recognition variability exhibited by adult CI users.Study DesignThirty postlingually deafened adults with CIs and thirty age‐matched normal‐hearing (NH) controls were enrolled.MethodsParticipants were assessed for recognition of words in sentences in noise and several non‐auditory measures of neurocognitive function. These non‐auditory tasks assessed global intelligence (problem‐solving), controlled fluency, working memory, and inhibition‐concentration abilities.ResultsFor CI users, faster response times during a non‐auditory task of inhibition‐concentration predicted better recognition of sentences in noise; however, similar effects were not evident for NH listeners.ConclusionsFindings from this study suggest that inhibition‐concentration skills play a role in speech recognition for CI users, but less so for NH listeners. Further research will be required to elucidate this role and its potential as a novel target for intervention.

Cochlear Implants in Adults: Effects of Age and Duration of Deafness on Speech Recognition.

Unexplained outcome variability exists among adults with cochlear implants (CIs). Two significant predictors are age and duration of deafness, with older patients and those with longer durations of deafness generally demonstrating poorer speech recognition. However, these factors are often highly correlated. Thus, it is unclear whether poorer outcomes should be attributed primarily to age-related declines or to the experience of auditory deprivation. Our aim was to examine the effects of aging and duration of hearing loss on outcomes for postlingually deaf adults with CIs. Retrospective review of adults who received CIs from 1983 to 2014. Tertiary adult CI program. Sixty-four adult patients with postlingual hearing loss beginning after age 12 years, full electrode insertion, normal cochlear anatomy, and availability of postoperative outcome measures. Cochlear implantation with 12 months or greater of device use. Postoperative pure-tone averages (0.5, 1, 2, and 3 kHz) and recognition of words in sentences (Hearing in Noise Test and AzBio). Age at postoperative testing had a negative partial correlation with AzBio scores, when controlling for duration of deafness, whereas duration of deafness had a positive partial correlation with AzBio scores, when controlling for age. No other effects were identified. Older age at testing was associated with poorer recognition of words in difficult sentences, suggesting that cognitive aging may negatively impact CI outcomes. Further studies are needed to examine how a long duration of auditory deprivation affects CI outcomes.

Effects of hearing loss on heart rate variability and skin conductance measured during sentence recognition in noise.

The purpose of the study was to determine the effects of hearing loss and noise on (1) two autonomic nervous system measures associated with stress (skin conductance and heart rate variability) and on (2) subjective ratings of workload/stress. The authors hypothesized that hearing loss would increase psychophysiological and subjective reactivity to noise during speech recognition tasks. Both psychophysiological and subjective indicators of workload/stress were expected to increase with a reduction in signal-to-noise ratio. Sentence recognition in the presence of babble noise was assessed in 15 adults with clinically normal hearing and 18 adults with sensorineural hearing loss. Mean sentence recognition was equalized for the two groups using an adaptive procedure to estimate 80% recognition of words in sentences. Sentences were then presented in quiet and at four fixed signal-to-noise ratios: -6, -3, 0, and +3 dB relative to the individually determined signal-to-noise thresholds. Electrocardiography and skin conductance recordings were obtained during each listening condition. The high-frequency spectral component of heart rate variability was extracted from the electrocardiographic recordings as a measure of parasympathetic nervous system activity. Subjective ratings of effort, mental demand, stress, and perceived performance were obtained after each listening condition using the National Aeronautics and Space Administration Task Load Index. Recognition scores referenced to the adaptive threshold were similar for the two groups. Participants with hearing loss showed a decrease in high-frequency heart rate variability at lower signal-to-noise ratios, whereas those with normal hearing did not. Skin conductance levels were not sensitive to changes in signal-to-noise ratio. However, overall skin conductance reactivity to noise (relative to quiet) was higher for those with hearing loss than for those with normal hearing. In contrast to the psychophysiological findings, there were no significant differences between subjective ratings for the two groups. Listeners with hearing loss show greater autonomic nervous system reactivity to babble noise during speech recognition than do listeners with normal hearing, when recognition performance is equal. The findings are consistent with the conclusion that listeners with hearing loss experience increased effort and/or stress during speech recognition in noise.

The effect of visual information on speech perception in noise by electroacoustic hearing

The addition of amplified low frequency hearing to cochlear implants has been shown to provide substantial performance benefits for cochlear implant (CI) users, particularly in noise. In the current study, we examined the extent to which the presence of visual information (facial movement during speech) augments perception for CI listeners with electroacoustic stimulation (EAS). Two experiments were conducted. In the first one, participants transcribed semantically anomalous phrases in quiet and noise. Intelligibility results showed modest improvements in intelligibility for low and high levels of noise, and dramatic gains (30+ percentage points) in midlevel noise. Error analyses conducted on the transcripts further suggest that the perceptual benefits extended beyond articulatory place information to that of facilitating lexical segmentation. In the second experiment, participants were tested on their recognition of words in sentences corrupted by noise. Results showed significant benefit of hearing aids in EAS patients. However, the benefit of acoustic hearing was not apparent when visual information was available. Our results will provide guidance for auditory rehabilitation strategies in this population.

Assessing Multimodal Spoken Word-in-Sentence Recognition in Children With Normal Hearing and Children With Cochlear Implants

To examine multimodal spoken word-in-sentence recognition in children. Two experiments were undertaken. In Experiment 1, the youngest age with which the multimodal sentence recognition materials could be used was evaluated. In Experiment 2, lexical difficulty and presentation modality effects were examined, along with test-retest reliability and validity in normal-hearing children and those with cochlear implants. Normal-hearing children as young as 3.25 years and those with cochlear implants just under 4 years who have used their device for at least 1 year were able to complete the multimodal sentence testing. Both groups identified lexically easy words in sentences more accurately than lexically hard words across modalities, although the largest effects occurred in the auditory-only modality. Both groups displayed audiovisual integration with the highest scores achieved in the audiovisual modality, followed sequentially by auditory-only and visual-only modalities. Recognition of words in sentences was correlated with recognition of words in isolation. Preliminary results suggest fair-to-good test-retest reliability. The results suggest that children's audiovisual word-in-sentence recognition can be assessed using the materials developed for this investigation. With further development, the materials hold promise for becoming a test of multimodal sentence recognition for children with hearing loss.

Training listeners to identify the sounds of speech: I. A review of past studies.

In this first section of a two-part article we offer an overview of research on listeners' abilities to learn to hear the spectral-temporal details of simple and complex sounds, both speech and non-speech. In the second article, to appear in the October issue of The Hearing Journal, we will describe a new training system based on that science that has recently completed clinical validation trials with users of hearing aids and of cochlear implants.1,2

The Performance/Intensity Function: An Underused Resource

The purpose of this tutorial is to demonstrate the potential value of the Performance versus Intensity (PI) function in both research and clinical settings. The PI function describes recognition probability as a function of average speech amplitude. In effect, it shows the cumulative distribution of useful speech information across the amplitude domain, as speech rises from inaudibility to full audibility. The basic PI function can be modeled by a cubed exponential function with three free parameters representing: (a) threshold of initial audibility, (b) amplitude range from initial to full audibility, and (c) recognition probability at full audibility. Phoneme scoring of responses to consonant-vowel-consonant words makes it possible to obtain complete PI functions in a reasonably short time with acceptable test-retest reliability. Two examples of research applications are shown here: (a) the preclinical behavioral evaluation of compression amplification schemes, and (b) assessment of the distribution of reverberation effects in the amplitude domain. Three examples of clinical application show data from adults with different degrees and configurations of sensorineural hearing loss. In all three cases, the PI function provides potentially useful information over and above that which would be obtained from measurement of Speech Reception Threshold and Maximum word recognition in Phonectically Balanced lists. Clinical application can be simplified by appropriate software and by a routine to convert phoneme recognition scores into estimates of the more familiar whole-word recognition scores. By making assumptions about context effects, phoneme recognition scores can also be used to estimate word recognition in sentences. It is hard to escape the conclusion that the PI function is an easily available, potentially valuable, but largely neglected resource for both hearing research and clinical audiology.

Cochlear implantation in Waardenburg's syndrome

Conclusions. Children with Waardenburg's syndrome (WS) derive significant benefit from cochlear implantation (CI) and do so to an extent that is comparable to that of the general population of implanted children. Although we report on a relatively small cohort, our data are useful for counseling the parents of children with WS considering CI. Objective. To present our experience with CI in patients with WS. Material and methods. A retrospective record review was conducted for five children who underwent CI in our department between 1993 and 2004. Results. Children with WS comprised 1.9% of our entire pediatric CI population: four girls had a familial history of WS and the phenotype of WS Type I, and one boy met the criteria for WS Type II. They were all diagnosed as having bilateral profound sensorineural hearing loss 4–24 weeks after birth. Rehabilitation was initiated immediately and included bilateral fitting of hearing aids and intensive speech and language therapy. Otoscopic and temporal bone high-resolution CT findings were normal in all patients. At surgery, all children were found to have a patent cochlea, and the electrodes were implanted into the scala tympani without difficulty. After 1.3–10.2 years of implant use all children achieved open-set recognition of 2-syllable words, with an average score of 81%. Four of the 5 children achieved open-set recognition of monosyllabic words (average score 40%) and 3 achieved open-set recognition of words in sentences (average score 81%).

Effects of Channel-to-Electrode Mappings on Speech Reception with the Ineraid Cochlear Implant

Research was conducted to assess multichannel saliency with the Ineraid cochlear prosthesis. The goal was to determine whether tonotopically ordered stimulation benefits speech reception. In a single high-performing subject, changes in speech reception were studied during two dramatic alterations to the normal (tonotopic) mapping between the sound-processors's four filter channels and the intracochlear electrode array: In one alteration, the four filter outputs were summed and delivered to one electrode; this single-channel mapping was worn for 7 days. In another alteration, the four filter outputs were connected in reverse tonotopic order to four intracochlear electrodes; this reversed mapping was worn for 3 days. When using the implant in conjunction with speechreading, all three mappings provided large gains over speechreading alone on the recognition of words in sentences. When using the implant alone (without speechreading), tests of consonant and vowel recognition, and the recognition of words in isolation and in sentences all showed substantial decreases in performance across the three mapping conditions: normal > single-channel > reversed. The patterns of segmental confusions and the relations among scores on different tests were highly consistent. Finally, the performance with the altered mappings was, in some ways, remarkably good. With single-channel mapping, 15% word recognition was obtained, much less than the 54% obtained with the normal mapping, but demonstrative of some open-set speech reception. With the reversed mapping, high levels of consonantal voicing and manner information were received, indicating good reception of time-intensity cues, but open-set word recognition was near zero. Despite the extensive spread of current associated with monopolar intracochlear stimulation, the Ineraid electrode array affords a degree of perceptual selectivity that substantially aids speech reception.

Probability theory and speech perception

Fletcher recognized the value of probability theory in developing a quantitative approach to speech perception—hence the articulation index (AI). He also recognized the need to allow for violations of the independence assumptions that underly basic probability theory. For example, in nonsense syllables, the probability (pw) of recognizing a word equals pnp, where pp is the probability of recognizing the constituent phonemes and n is the number of phonemes per word. In real words, however, pw=pjp, where n≥j≥1. Similarly, extending the methods of AI, the probability of recognition of words in sentences (spw) can be shown to be related to the probability of recognition in isolation (ipw) by the equation spw=1−(1−ipw)k, where k is an exponent reflecting the contribution of the sentence context. From these two basic equations one can derive relationships among many measures of speech perception, ranging from the phonetic level to the sentence level. The empirical values of the exponents j and k can be used both to quantify the effects of various structural and contextual constraints and to assess an individual’s use of those constraints. [Work supported by NIDCD Grant No. 10078.]

Evidence of word class effects for word recognition in sentences

Previous research has reported that because content words tend to be stressed and function words tend to be unstressed, word class (content−function word) perceptual differences are an artifact of stress differences [A. Cutler and D. Foss, Language Speech 20, 1–10 (1977)]. The present research provides evidence for the validity of word class differences for gated words in a sentence context. Subjects heard successively longer presentations of each target word. The first presentation included the sentence up to the target word onset. The second presentation included the same sentence context plus the first 50 ms of the target word. The duration of each successive presentation was 50 ms longer than the previous presentation. After each presentation, subjects were asked to identify the target word. The target words were content and function words balanced for stress. The results demonstrated that word class, independent of stress, significantly influenced the number of presentations required for identification. The results also showed that for the first presentation, subjects significantly chose words of the same word class as the target word, indicating that word class information is available before phonetic information. [Work supported by Northwestern University dissertation year grant.]

Speechreading enhancement by voice fundamental frequency: the effects of Fo contour distortions.

Recognition of words in sentences of known topic was measured in normally hearing adults via speechreading alone and speechreading supplemented with auditory presentation of signals intended to convey variations of voice fundamental frequency (Fo) over time. Three signals were used: (a) the low-pass filtered output of an electroglottograph (unprocessed Fo), (b) a constant amplitude sine wave whose instantaneous frequency was intended to equal that of Fo (processed Fo), and (c) the same sine wave restricted to a small number of discrete frequency steps (quantized Fo). As the number of steps in the quantized Fo contours increased from 1 to 12, the speechreading enhancement effect increased. The quantized Fo contour with 12 steps was as effective as the processed Fo contour (without quantization), but this processed contour was significantly less effective than the unprocessed electroglottograph signal. The results show that the auditory Fo speechreading enhancement effect is sensitive to the errors introduced by the Fo extraction and regeneration process used in this study. It is also sensitive to the quantization of Fo contours into less than 12 steps. Whether more than 12 steps are required for the full enhancement effect remains to be determined.

Relations among different measures of speech reception in subjects using a cochlear implant.

A comprehensive set of speech reception measures were obtained in a group of about 20 postlingually deafened adult users of the Ineraid multichannel cochlear implant. The measures included audio, visual, and audiovisual recognition of words embedded in two types of sentences (with differing degrees of difficulty) and audio-only recognition of isolated monosyllabic words, consonant identification (12 alternatives, /Ca/), and vowel identification (8 alternatives, /bVt/). For most implantees, the audiovisual gains in the sentence tests were very high. Quantitative relations among audio-only scores were assessed using power-law transformations suggested by Boothroyd and Nittrouer [J. Acoust. Soc. Am. 84, 101-114 (1988)] that can account for the benefit of sentence context (via a factor k) and the relation between word and phoneme recognition (via a factor j). Across the broad range of performance that existed among the subjects, substantial order was observed among measures of speech reception along the continuum from recognition of words in sentences, words in isolation, speech segments, and the retrieval of underlying phonetic features. Correlations exceeded 0.85 among direct and sentence-derived measures of isolated word recognition as well as among direct and word-derived measures of segmental recognition. Results from a variety of other studies involving presentation of limited auditory signals, single-channel and multichannel implants, and tactual systems revealed a similar pattern among word recognition, overall consonant identification performance, and consonantal feature recruitment. Finally, improving the reception of consonantal place cues was identified as key to producing the greatest potential gains in speech reception.