• 말소리와 음성과학
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• 제2권1호
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• pp.3-11
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• 2010

The present study confirmed the intelligibility improvement benefit of clear speech by investigating the intelligibility of Korean stops produced in different speaking styles: conversational, citation-form, and clear speech. This finding supports the Hypo- & Hyper-speech theory that speakers adjust vocal effort to accommodate hearers' speech perception difficulty. A progressive intelligibility improvement was found for the three speaking styles investigated: clear speech was more intelligible than citation-form speech citation-form speech was more intelligible than conversational speech and clear speech was also more intelligible than conversational speech. These findings suggest that the manipulations to elicit three distinct speaking styles in a laboratory setting were successful. Korean lenis stops showed the least intelligibility improvement among the three Korean stop types, and this result suggests that lenis stops should be more resistant to intelligibility enhancement efforts in clear speech than aspirated and fortis stops.

• Archives of Plastic Surgery
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• 제36권3호
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• pp.294-298
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• 2009

Purpose: The pharyngeal flap is one of the popular surgical method to treat the problem of velopharyngeal dysfunction. This study evaluated speech outcomes of patients who underwent superiorly based pharyngeal flap surgery based on timing of surgery. Methods: A restrospective review of 50 patients who underwent pharyngeal flap surgery for velopharyngeal insufficiency between September 1996 and January 2008 was undertaken. Thirty patients with an available preoprative and postoperative speech assessments with at least 6 months of follow-up were included in this study. We checked out the significance of speech improvement after surgery analysing preoperative and postoperative scoring of speech assessment. We also investigated the direct relationship between the age at surgery and the degree of speech improvement, and the improvement score in different age groups. Results: The mean score of preoperative speech was $52.6{\pm}7.4points$ and postoperative speech was $58.6{\pm}6.5points$, which presented significant postoperative speech improvement with an average of 5.9 points(p<0.01). There was a significant inverse relationship between the age at operation and speech improvement degree(p<0.01, r = -0.54). Comparing the age groups, the age group of 4 to 5 years presented statistically significant speech improvement(p<0.01). Conclusion: we propose that all patients indicated should take pharyngeal flap irrespective of age. In this study, the younger the age at surgery, the higher degree of speech improvement, for which we suggest that surgical approach should be undertaken as early as possible, especially younger than age 5 years.

• 말소리와 음성과학
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• 제7권1호
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• pp.47-55
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• 2015

This study examined whether speech acceptability was changed under various conditions of prosodic manipulations. Both speech rate and voice loudness reportedly are associated with acceptability and intelligibility. Speech samples by twelve speakers with mild dysarthria were recorded. Speech rate and loudness changes were made by digitally manipulating habitual sentences. 3 different loudness levels (70, 75, & 80dB) and 4 different speech rates (normal, 20% rapidly, 20% slowly, & 40% slowly) were presented to 12 SLPs (speech language pathologists). SLPs evaluated sentence acceptability by 7-point Likert scale. Repeated ANOVA were conducted to determine if the prosodic type of resynthesized cue resulted in a significant change in speech acceptability. A faster speech rate (20% rapidly) rather than habitual and slower rates (20%, 40% slowly) resulted in significant improvement in acceptability ratings (p <.001). An increased vocal loudness (up to 80dB) resulted in significant improvement in acceptability ratings (p <.05). Speech rate and loudness changes in the prosodic properties of speech may contribute to improved acceptability.

• 말소리와 음성과학
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• 제6권2호
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• pp.29-34
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• 2014

In the Vector Taylor Series (VTS)-based noisy speech recognition methods, Hidden Markov Models (HMM) are usually trained with clean speech. However, better performance is expected by training the HMM with noisy speech. In a previous study, we could find that Minimum Mean Square Error (MMSE) estimation of the training noisy speech in the log-spectrum domain produce improved recognition results, but since the proposed algorithm was done in the log-spectrum domain, it could not be used for the HMM adaptation. In this paper, we modify the previous algorithm to derive a novel mathematical relation between test and training noisy speech in the cepstrum domain and the mean and covariance of the Multi-condition TRaining (MTR) trained noisy speech HMM are adapted. In the noisy speech recognition experiments on the Aurora 2 database, the proposed method produced 10.6% of relative improvement in Word Error Rates (WERs) over the MTR method while the previous MMSE estimation of the training noisy speech produced 4.3% of relative improvement, which shows the superiority of the proposed method.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 제14회 신호처리 합동 학술대회 논문집
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• pp.503-506
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• 2001

본 논문에서는 마이크 입력레벨 조절기의 구현과 이를 이용한 인식률의 향상을 다룬다. 마이크를 통한 음성 입력이 너무 작거나 너무 크면 인식률에 직접 영향을 미치므로 인식에 적합한 입력레벨로 조절할 필요가 있다. 자동 입력레벨 조절기의 구현을 위해 고려할 사항을 연구했으며, 이를 통해 PC환경의 입력레벨 조절기를 구현했다. 수집된 음성 데이터베이스는 켑스트럼 평균차감법(CMS)을 이용하여 채널왜곡을 보상했으며, 구현된 조절기를 이용하여 실험한 결과, 이용하지 않은 경우에 비해 약 50%의 오인식율을 줄일 수 있었다.

• 음성과학
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• 제11권1호
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• pp.7-20
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• 2004

In this paper, we propose a two-step noise compensation algorithm in feature extraction for achieving robust speech recognition. The proposed method frees us from requiring a priori information on noisy environments and is simple to implement. First, in frequency domain, the Harmonics-based Spectral Subtraction (HSS) is applied so that it reduces the additive background noise and makes the shape of harmonics in speech spectrum more pronounced. We then apply a judiciously weighted variance Feature Vector Normalization (FVN) to compensate for both the channel distortion and additive noise. The weighted variance FVN compensates for the variance mismatch in both the speech and the non-speech regions respectively. Representative performance evaluation using Aurora 2 database shows that the proposed method yields 27.18% relative improvement in accuracy under a multi-noise training task and 57.94% relative improvement under a clean training task.

• 한국음향학회:학술대회논문집
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• 한국음향학회 1998년도 제15회 음성통신 및 신호처리 워크샵(KSCSP 98 15권1호)
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• pp.225-230
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• 1998

In this paper, a Kalman filter approach for enhancing speech signals degraded by statistically independent additive nonstationary noise is developed. The autoregressive hidden markov model is used for modeling the statistical characteristics of both the clean speech signal and the nonstationary noise process. In this case, the speech enhancement comprises a weighted sum of conditional mean estimators for the composite states of the models for the speech and noise, where the weights equal to the posterior probabilities of the composite states, given the noisy speech. The conditional mean estimators use a smoothing spproach based on two Kalmean filters with Markovian switching coefficients, where one of the filters propagates in the forward-time direction with one frame. The proposed method is tested against the noisy speech signals degraded by Gaussian colored noise or nonstationary noise at various input signal-to-noise ratios. An app개ximate improvement of 4.7-5.2 dB is SNR is achieved at input SNR 10 and 15 dB. Also, in a comparison of conventional and the proposed methods, an improvement of the about 0.3 dB in SNR is obtained with our proposed method.

• 음성과학
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• 제15권2호
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• pp.55-65
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• 2008

Recently, the multi-model based speech recognizer has been used quite successfully for noisy speech recognition. For the selection of the reference HMM (hidden Markov model) which best matches the noise type and SNR (signal to noise ratio) of the input testing speech, the estimation of the SNR value using the VAD (voice activity detection) algorithm and the classification of the noise type based on the GMM (Gaussian mixture model) have been done separately in the multi-model framework. As the SNR estimation process is vulnerable to errors, we propose an efficient method which can classify simultaneously the SNR values and noise types. The KL (Kullback-Leibler) distance between the single Gaussian distributions for the noise signal during the training and testing is utilized for the classification. The recognition experiments have been done on the Aurora 2 database showing the usefulness of the model compensation method in the multi-model based speech recognizer. We could also see that further performance improvement was achievable by combining the probability density function of the MCT (multi-condition training) with that of the reference HMM compensated by the D-JA (data-driven Jacobian adaptation) in the multi-model based speech recognizer.

• 대한두개안면성형외과학회지
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• 제21권1호
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• pp.22-26
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• 2020

Background: This study investigated the outcomes of pharyngeal flap surgery in Asian patients with velopharyngeal dysfunction (VPD), with a focus on postoperative improvements in speech articulation and complications. Additionally, this study explored whether the cause of VPD and the timing of surgery affected outcomes in terms of speech improvement. Methods: A retrospective review was conducted of the medical records of 72 Asian VPD patients who underwent pharyngeal flap surgery performed by a single surgeon from 1996 to 2014. Operative complications were analyzed for all 72 patients, and preoperative and postoperative speech articulation tests were compared for the subset of 43 patients in whom such testing was possible. The relationships of age at surgery and the cause of VPD with the extent of improvement in speech articulation were also investigated. Results: Nine of the 72 patients (13%) experienced wound-related complications. Furthermore, 34 patients (47%) reported persistent snoring lasting for over 3 months, and 16 (22%) reported snoring for over 1 year. Three patients (4%) underwent reoperation. Speech articulation scores significantly improved postoperatively across all groups. Younger age at surgery was associated with greater improvements in speech outcomes, but no significant relationship was found between the cause of VPD and the extent of the postoperative improvement in speech outcomes. Conclusion: Speech outcomes improved after pharyngeal surgery in Asian patients with VPD. Early surgery was associated with favorable speech outcomes, but no association was found between the cause of VPD and postoperative speech outcomes.

• Journal of Audiology & Otology
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• 제24권2호
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• pp.91-98
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• 2020

Background and Objectives: This study aimed to compare functional hearing with the use of a personal sound amplification product (PSAP) or a basic hearing aid (HA) among sensorineural hearing impaired listeners. Subjects and Methods: Nineteen participants with mild-to-moderate sensorineural hearing loss (SNHL) (26-55 dB HL; pure-tone average, 0.5-4 kHz) were prospectively included. No participants had prior experience with HAs or PSAPs. Audiograms, speech intelligibility in both quiet and noisy environments, speech quality, and preference were assessed in three different listening conditions: unaided, with the HA, and with the PSAP. Results: The use of PSAP was associated with significant improvement in pure-tone thresholds at 1, 2, and 4 kHz compared to the unaided condition (all p<0.01). In the quiet environment, speech intelligibility was significantly improved after wearing a PSAP compared to the unaided condition (p<0.001), and this improvement was better than the result obtained with the HA. The PSAP also demonstrated similar improvement in the most comfortable levels compared to those obtained with the HA (p<0.05). However, there was no significant improvement of speech intelligibility in a noisy environment when wearing the PSAP (p=0.160). There was no significant difference in the reported speech quality produced by either device or in participant preference for the PSAP or HA. Conclusions: The current result suggests that PSAPs provide considerable benefits to speech intelligibility in a quiet environment and can be a good alternative to compensate for mild-to-moderate SNHL.