Language-specific, hearing-related changes in vowel spaces: a preliminary study of English- and Spanish-speaking cochlear implant users.

OBJECTIVE: This study investigates the role of hearing in vowel productions of postlingually deafened cochlear implant users. Two hypotheses are tested that derive from the view that vowel production is influenced by competing demands of intelligibility for the listener and least effort in the speaker: 1) Hearing enables a cochlear implant user to produce vowels distinctly from one another; without hearing, the speaker may give more weight to economy of effort, leading to reduced vowel separation. 2) Speakers may need to produce vowels more distinctly from one another in a language with a relatively "crowded" vowel space, such as American English, than in a language with relatively few vowels, such as Spanish. Thus, when switching between hearing and non-hearing states, English speakers may show a tradeoff between vowel distinctiveness and least effort, whereas Spanish speakers may not. DESIGN: To test the prediction that there will be a reduction of average vowel spacing (AVS) (average intervowel distance in the F1-F2 plane) with interrupted hearing for English-speaking cochlear implant users, but no systematic change in AVS for Spanish cochlear implant users, vowel productions of seven English-speaking and seven Spanish-speaking cochlear implant users, who had been using their implants for at least 1 yr, were recorded when their implant speech processors were turned off and on several times in two sessions. RESULTS: AVS was consistently larger for the English speakers with hearing than without hearing. The magnitude and direction of AVS change was more variable for the Spanish speakers, both within and between subjects. CONCLUSION: Vowel distinctiveness was enhanced with the provision of some hearing in the language group with a more crowded vowel space but not in the language group with fewer vowels. The view that speakers seek to minimize effort while maintaining the distinctiveness of acoustic goals receives some support.     

Acoustic voice analysis in phonatory fistuloplasty after total laryngectomy

A comparative study was made of the voices of three groups of male patients by acoustic analysis of sustained phonation of the vowel /a/: 1) 20 patients who had undergone total laryngectomy and phonatory fistuloplasty, fitted with a Herrmann voice prosthesis, who had achieved successful prosthetic speech; 2) 20 laryngectomized patients with good quality esophageal speech, and 3) 20 subjects with normal voices. Statistical analysis of fundamental frequency disclosed significant differences between groups, the group with phonatory prostheses having the closest to normal voice of the fistuloplastic groups. There were no statistically significant differences in jitter, shimmer, and the harmonic-to-noise ratio between the esophageal and prosthetic voice groups, which suggests that the disturbances in the vibratory esophageal ring were similar.     

Covariation of cochlear implant users' perception and production of vowel contrasts and their identification by listeners with normal hearing.

This study investigates covariation of perception and production of vowel contrasts in speakers who use cochlear implants and identification of those contrasts by listeners with normal hearing. Formant measures were made of seven vowel pairs whose members are neighboring in acoustic space. The vowels were produced in carrier phrases by 8 postlingually deafened adults, before and after they received their cochlear implants (CI). Improvements in a speaker's production and perception of a given vowel contrast and normally hearing listeners' identification of that contrast in masking noise tended to occur together. Specifically, speakers who produced vowel pairs with reduced contrast in the pre-CI condition (measured by separation in the acoustic vowel space) and who showed improvement in their perception of these contrasts post-CI (measured with a phoneme identification test) were found to have enhanced production contrasts post-CI in many cases. These enhanced production contrasts were associated, in turn, with enhanced masked word recognition, as measured from responses of a group of 10 normally hearing listeners. The results support the view that restoring self-hearing allows a speaker to adjust articulatory routines to ensure sufficient perceptual contrast for listeners.     

无喉者发不同元音时的声学参数及气管内压力比较

目的　比较无喉者发不同元音时的声学参数及气管内压的异同。方法　检测了 2 4例喉全切除气管断端膜样部食管吻合分流发声重建术后患者和 16例喉全切除术后食管音患者分别发元音 a 和 i 时的声学参数 ,测定了 2 0例发声重建术后患者分别发 a 和 i 时的气管内压 ,并进行统计学分析。结果　两组无喉患者发不同元音 a 和 i 时 ,其声学参数无显著性差异 (P >0 .0 5 ) ,发声重建术后患者的气管内压发 i 音时较发 a 音时高 ,有显著性差异 (P <0 .0 5 )。结论　应用元音 a 和 i 在评价无喉者发声的声学参数有一致的临床意义 ;而发声重建术后患者在发不同元音时 ,气管内压值不同     

Acoustic differences between content and function words in amyotrophic lateral sclerosis.

Studies describing acoustic characteristics of speech produced by individuals with dysarthria may help to explain intelligibility deficits for these speakers. One goal of the current study was to investigate the manner and extent to which nine speakers with mild to moderate dysarthria associated with amyotrophic lateral sclerosis (ALS) and nine healthy speakers acoustically distinguished /i/, /ae/, /u/, and /a/ in content and function words. A further aim was to evaluate the relationship between impaired speech in ALS and the magnitude of acoustic differences for vowels in content and function words. Speakers read the Farm Passage at a comfortable or habitual rate. F1 and F2 midpoint frequencies were measured, and vowel space areas were calculated. Vowel durations also were measured. The magnitude of F1, F2, vowel space area, and duration differences for vowels in content and function words was not statistically different for speakers with ALS and healthy controls. In addition, with the exception of /i/ produced by some speakers with ALS, vowel duration tended to be shorter in function words. Average F1 and F2 values for function words also tended to be centralized relative to content words. Although vowel space area differences for the two speaker groups were not statistically significant, there was a tendency for the difference in vowel space area for content and function words to be smaller for speakers with ALS than for controls. Regression analyses further indicated that the magnitude of temporal differences for vowels in content and function words was a better predictor of impaired speech than the magnitude of spectral differences for vowels in content and function words. One clinical implication is that individuals with ALS may benefit from therapy techniques targeting temporal properties of the acoustic signal.     

A comparative acoustic analysis of voice production by near-total laryngectomy and normal laryngeal speakers.

Limited objective data are available on voice characteristics of patients following near-total laryngectomy. Acoustic characteristics of near-total voice were quantified and compared to laryngeal voice production. High quality audio recordings were obtained from 11 subjects who had undergone near-total laryngectomy and 11 age-matched laryngeal speakers. Subjects performed vocal tasks which provided frequency, intensity and duration measures. These data were computer analyzed and indicated that substantial inter and intrasubject variability existed in the acoustic measures for near-total laryngectomy patients. These patients demonstrated a general restriction in fundamental frequency, reduced intensity and a limitation in duration of phonation when compared to laryngeal speakers.     

Tongue strength: Part II: In artificial alaryngeal speech

Tongue strength does not appear to be reduced in proficient esophageal speakers. However, no data exist on tongue strength for laryngectomized subjects who have not developed esophageal speech. Anterior and lateral tongue strength measures were obtained from 13 laryngectomized subjects who used an artificial larynx and 15 normal subjects by means of a pressure transducer and recording device. The results indicated that laryngectomized subjects had significantly weaker tongues in two of three directions measured. It was concluded that laryngectomy may affect tongue strength, but that the method of alaryngeal speech utilized postoperatively influences the return to normal.     

Bite block vowel production in apraxia of speech

PURPOSE: This study explored vowel production and adaptation to articulatory constraints in adults with acquired apraxia of speech (AOS) plus aphasia. METHOD: Five adults with acquired AOS plus aphasia and 5 healthy control participants produced the vowels [i], [epsilon], and [ae] in four word-length conditions in unconstrained and bite block conditions. In addition to acoustic and perceptual measures of vowel productions, individually determined idealized vowels based on each participant's best performance were used to assess vowel accuracy and distinctiveness. RESULTS: Findings showed (a) clear separation of vowel formants in speakers with AOS; (b) impaired vowel production in speakers with AOS, shown by perceptual measures of vowel quality and acoustic measures of vowel accuracy and contrastivity; and (c) incomplete compensation to bite block compensation both for individuals with AOS and for healthy controls. CONCLUSIONS: Although adults with AOS were less accurate overall in vowel production than unimpaired speakers, introduction of a bite block resulted in similar patterns of decreased vowel accuracy for the two groups. Findings suggest that feedback control for vowel production is relatively intact in these individuals with AOS and aphasia. Predominant use of feedback control mechanisms is hypothesized to account for characteristic vowel deficits of the disorder.     

Comparison of voice characteristics following three different methods of treatment for laryngeal cancer

INTRODUCTION: Laryngeal cancer treatment has become more complex and diversified in past decades. Many different methods of treatment have evolved, and most have been able to restore the patient's function and maintain some form of functional speech. This study was designed to evaluate the voice and speech characteristics of patients who have undergone different treatments for laryngeal cancer and to compare those characteristics with those of age- and sex-matched normal laryngeal speakers. METHODS: Twenty-two male subjects participated in the study. Five men were treated with radiation therapy, 6 men had supracricoid partial laryngectomy, 6 men had undergone total laryngectomy with tracheoesophageal puncture, and 5 men were normal laryngeal speakers. Acoustic, aeromechanical, and perceptual assessments of speech were collected. RESULTS: Significant age effects were found for maximum phonation times. As age increased, maximum phonation time decreased (p < .005). Significant differences were found between groups for the following dependent variables: percentage of voiceless phonation, maximum phonation time, laryngeal airway resistance, subglottal pressure, oral flow, and word intelligibility. Trends in the data for differences between groups were noted for the following acoustic variables: noise-to-harmonics ratio, jitter, and shimmer. CONCLUSIONS: All patients developed or maintained a source of voicing after treatment and could use speech functionally, as demonstrated by normal sentence intelligibility. The radiation treatment group had voices that differed the least from the control group, whereas the opposite was true for the surgical groups, especially for those with total laryngectomy.     

The effect of phonological neighborhood density on vowel articulation.

Recent literature suggests that phonological neighborhood density and word frequency can affect speech production, in addition to the well-documented effects that they have on speech perception. This article describes 2 experiments that examined how phonological neighborhood density influences the durations and formant frequencies of adults' productions of vowels in real words. In Experiment 1, 10 normal speakers produced words that covaried in phonological neighborhood density and word frequency. Infrequent words with many phonological neighbors were produced with shorter durations and more expanded vowel spaces than frequent words with few phonological neighbors. Results of this experiment confirmed that this effect was not related to the duration of the vowels constituting the high- and low-density words. In Experiment 2, 15 adults produced words that varied in both word frequency and neighborhood density. Neighborhood density affected vowel articulation in both high- and low-frequency words. Moreover, frequent words were produced with more contracted vowel spaces than infrequent words. There was no interaction between these factors, and the vowel duration did not vary as a function of neighborhood density. Taken together, the results suggest that neighborhood density affects vowel production independent of word frequency and vowel duration.     

喉全切除发声重建术后发声功能评估

目的 :对喉全切除气管断端膜样部食管吻合分流发声重建术后气管食管 (TE)音患者的发声功能进行客观评估。方法 :对TE音组、食管音组及健康组进行发声声学分析及最大发声时间比较。测定了 2 0例TE音患者舒适发声时的气管内压。在电子喉镜下观察TE音和食管音患者发声时咽食管段黏膜的振动情况及“新声门”的形态。结果 :TE音与食管音相比各发声声学参数差异均无统计学意义 ,而与健康组相比 ,除基频、振幅外 ,基频微扰、振幅微扰、谐噪比和标准化噪声能量等参数均有统计学意义。TE音患者舒适发声时的气管内压为(2 .86± 0 .6 9)kPa。两组无喉音发声时的咽食管段黏膜大多振动规律 ,新声门形状多为环状。结论 :TE音组的发声声学特征同食管音组相近 ,与健康组相比均有显著差异 ,但TE音的音调更接近健康组。本发声重建术后患者发声省力。     

Tongue strength: Part I: Following total laryngectomy

Surgical repositioning of the genioglossus muscle, as in total laryngectomy, may have an adverse effect on the protrusive strength of the tongue. To test this premise, anterior and lateral tongue strength measures were obtaind from 10 laryngectomized and 15 normal subjects by means of a pressure transducer and recording device. The results indicated no significant difference between laryngectomized and normal subjects on tongue strength measures. Further, all laryngectomized subjects were judged to have good to excellent esophageal speech. It was concluded that laryngectomy does not adversely affect the major musculature concerned with protrusive tongue strength for proficient esophageal speakers.     

Talker differences in clear and conversational speech: acoustic characteristics of vowels.

PURPOSE: To determine the specific acoustic changes that underlie improved vowel intelligibility in clear speech. METHOD: Seven acoustic metrics were measured for conversational and clear vowels produced by 12 talkers-6 who previously were found (S. H. Ferguson, 2004) to produce a large clear speech vowel intelligibility effect for listeners with normal hearing identifying vowels in background noise (the big benefit talkers), and 6 who produced no clear speech vowel intelligibility benefit (the no benefit talkers). RESULTS: For vowel duration and for certain measures of the overall acoustic vowel space, the change from conversational to clear speech was significantly greater for big benefit talkers than for no benefit talkers. For measures of formant dynamics, in contrast, the clear speech effect was similar for the 2 groups. CONCLUSION: These results suggest that acoustic vowel space expansion and large vowel duration increases improve vowel intelligibility. In contrast, changing the dynamic characteristics of vowels seems not to contribute to improved clear speech vowel intelligibility. However, talker variability suggested that improved vowel intelligibility can be achieved using a variety of clear speech strategies, including some apparently not measured here.     

Does lack of glottic closure affect quality of life as a cause of constipation in laryngectomized patients?

The permanent disappearance of glottic closure eventually causes inadequate defecatory propulsion resulting in functional constipation. The aim of this study is to reveal functional constipation probably induced by lack of glottic closure in laryngectomized patients. The study was conducted in a prospective, tertiary care center. Forty patients who had undergone total laryngectomy (study group) and 30 who had undergone microlaryngoscopic surgery (control group) were evaluated. Based on the European Organisation for Research and Treatment of Cancer, Quality of Life Questionnaires C30, the presence of functional constipation was investigated using the Rome II diagnostic criteria and was confirmed by measurement of colonic transit time using a radiopaque marker test. Functional constipation and colonic transit time were found to be increased and statistically significant in laryngectomized patients (70 %) compared with the control group (26 %) (p < 0.01). Functional constipation is more prevalent among laryngectomized patients. When evaluating quality of life of patients undergoing laryngectomy, colorectal functions must be taken into consideration.     

Low-frequency energy deficit in electrolaryngeal speech.

The present exploratory project was undertaken (a) to determine the relative strength of low-frequency energy in the output of one widely used electronic artificial larynx (Servox) and (b) to assess the relative strength of low-frequency energy in vowels produced by users of this type of artificial larynx. We hypothesized that the outputs of electronic artificial larynges and the vowels produced by laryngectomized users of these devices would be characterized by significant deficits in low-frequency energy level. Five users of electronic larynges and 10 normal speakers (5 female and 5 male) provided the speech samples. Results of spectral analyses indicated that there was a significant deficit in low-frequency energy both in the acoustic signals generated by a Servox electronic larynx and in vowels produced by laryngectomized users of this type of electronic larynx. Based on these findings, a second order filter was designed and implemented digitally to compensate for the observed deficit in low-frequency energy. A perceptual experiment was completed to evaluate the effect of low-frequency enhancement on perceived speech quality. Ninety-eight percent (+/- 2%) of the responses of listeners indicated that low-frequency enhanced speech samples had better vocal quality or were more pleasant to listen to than the original speech samples. We conclude that consideration for enhancing low-frequency characteristics is warranted in the design of improved prosthetic devices for alaryngeal speakers.     

Training effects on vowel production by two profoundly hearing-impaired speakers

Two profoundly hearing-impaired adolescents received systematic speech training to improve their production of the vowels /i/ and /ae/. Acoustic measures of F1, F2, and duration, and listener judgements of vowel acceptability, were used to quantify vowel production before and after training. Both subjects demonstrated significant changes in their production of the two vowels at the acoustic and perceptual levels following treatment. The changes were highly individualized. For some features, significant improvement occurred posttreatment with differences between the hearing-impaired subject and a control group of subjects with normal hearing no longer present. There was a significant improvement in the acceptability of the two vowels in each subject's speech after training. Vowel duration remained unchanged in the speech of one subject whereas it increased in the speech of the other subject following training. There was a trend toward reduced token-to-token variation in the posttreatment samples. Acoustic and perceptual measures also were obtained on two vowels not directly trained in the program. Significant changes occurred in the production of these segments but some of the changes resulted in greater deviation in the post- than in the pretreatment samples.     

Comparación de la producción vocal en niños con hipoacusia prelocutiva con adaptación audioprotésica e implante coclear con normooyentes

Introduction and objectivesInadequate auditory feedback in prelingually deaf children alters the articulation of consonants and vowels.The purpose of this investigation was to compare vowel production in Spanish-speaking deaf children with cochlear implantation, and with hearing-aids with normal-hearing children by means of acoustic analysis of formant frequencies and vowel space.MethodsA total of 56 prelingually deaf children (25 with cochlear implants and 31 wearing hearing-aids) and 47 normal-hearing children participated. The first 2 formants (F1 and F2) of the five Spanish vowels were measured using Praat software. One-way analysis of variance (ANOVA) and post hoc Scheffé test were applied to analyze the differences between the 3 groups. The surface area of the vowel space was also calculated.ResultsThe mean value of F1 in all vowels was not significantly different between the 3 groups. For vowels /i/, /o/ and /u/, the mean value of F2 was significantly different between the 2 groups of deaf children and their normal-hearing peers.ConclusionBoth prelingually hearing-impaired groups tended toward subtle deviations in the articulation of vowels that could be analyzed using an objective acoustic analysis programme.     

Acoustic and perceptual characteristics of vowels produced during simultaneous communication

This study investigated the acoustical and perceptual characteristics of vowels in speech produced during simultaneous communication (SC). Twelve normal hearing, experienced sign language users were recorded under SC and speech alone (SA) conditions speaking a set of sentences containing monosyllabic words designed for measurement of vowel duration, formant frequencies, and fundamental frequency in consonant-vowel-consonant (CVC) syllables and 60 listeners audited the speech samples. Although results indicated longer sentence and vowel durations for SC than SA, the data showed no difference in spectral characteristics of vowels produced during SC versus SA, indicating no degradation of vowel spectrum by rate alteration during SC. Further, no difference was found in listeners' ability to identify vowels produced during SC versus SA, indicating no degradation of vowel perceptual cues during SC. These conclusions are consistent with previous research indicating that temporal alterations produced by SC do not produce degradation of segmental acoustical characteristics of spoken English. LEARNING OUTCOMES: As a result of this activity, the participant will be able to (1) describe simultaneous communication; (2) explain the role of simultaneous communication in communication with children who are deaf; (3) describe vowel acoustics in English speech; (4) discuss methods of measuring vowel perception; (5) specify the acoustic characteristics of vowels produced during simultaneous communication; and (6) specify the ability of listeners to perceive vowels in speech produced during simultaneous communication.     

Audibility of American English vowels produced by English-, Chinese-, and Korean-native speakers in long-term speech-shaped noise

The purpose of this study was to evaluate whether there were significant differences in audibility of American English vowels in noise produced by non-native and native speakers. Detection thresholds for 12 English vowels with equalized durations of 170 ms produced by 10 English-, Chinese- and Korean-native speakers were measured for young normal-hearing English-native listeners in the presence of speech-shaped noise presented at 70 dB SPL. Similar patterns of vowel detection thresholds as a function of the vowel category were found for native and non-native speakers, with the highest thresholds for /u/ and /?/ and lowest thresholds for /i/ and /e/. In addition, vowel detection thresholds for non-native speakers were significantly lower and showed greater speaker variability than those for native speakers. Thresholds for vowel detection predicted from an excitation-pattern model corresponded well to behavioral thresholds, implying that vowel detection was primarily determined by the vowel spectrum regardless of speaker language background. Both behavioral and predicted thresholds showed that vowel audibility was similar or even better for non-native speakers than for native speakers, indicating that vowel audibility did not account for non-native speakers' lower-than-native intelligibility in noise. Effects of non-native speakers' English proficiency level on vowel audibility are discussed.     

An acoustic and perceptual study of final stops produced by profoundly hearing impaired adolescents.

PURPOSE: This study investigated formant frequencies for their role as acoustic and perceptual correlates to the place of articulation of Cantonese final stops produced by profoundly hearing impaired speakers. METHOD: Speakers were 10 Cantonese adolescents (mean age=13;5 [years;months]) who were profoundly hearing impaired (HI). Control speakers were 10 adolescents (mean age=13;5) with normal hearing. Stimuli were Cantonese words that were minimally contrastive in place of final stops (/p, t, k/). Listeners were 10 final-year speech therapy students. The frequencies of F1, F2, and F3 were measured at the middle, 40 ms before the end, and at the end of the vocalic segments. RESULTS: Control speakers distinguished place contrasts through formant frequency differences at the end positions of the vowels. HI speakers produced final stops with missing formant transitions and neutralized vowels preceding final stops. Listeners relied on F2 transition cues for stops produced by control speakers, whereas F1 and F3 transition cues were used for stops produced by HI speakers. CONCLUSIONS: Formant frequencies of final stops produced by HI speakers showed reduced place distinction. When listeners identified the place of final stops produced by HI speakers, they relied on formant frequency cues that were different from those used for stops produced by control speakers.