• 대한후두음성언어의학회지
• /
• 제33권2호
• /
• pp.64-76
• /
• 2022

Praat is a useful analysis tool for linguists, engineers, doctors, speech-language pathologits, music majors, and natural scientists. Basic parameters including duration, pitch, energy and perturbation parameters such as jitter and shimmer can be easily measured and manipulated in the sound editor. When a more in-depth analysis is needed, it is recommended to understand the advanced menus of the object window and learn how to use them. Among the object window menus, vowel formant analysis, spectrum analysis, and cepstrum analysis can be cited as useful ones in the clinical field. The spectrum object can be usefully used for voice quality measurement and diagnosis of patients with voice disorders by showing the energy distribution according to frequency axis (domain). A cepstrum object is useful for speech analysis when periodicity of the sound object is not measurable. The low to high ratio obtained from the spectral object and the CPPs measured from the cepstrum object have attracted many researchers, and it has been proven that the CPPs measured in Praat are relatively excellent.

• 인터넷정보학회논문지
• /
• 제18권1호
• /
• pp.57-64
• /
• 2017

오늘날 자동차 제조회사들은 차량의 기능과 성능을 향상시키는 기술에 주안을 두는 것은 기본이고, 시장성의 극대화 및 고객 만족도를 높이기 위해 고품질 오디오 장치 구축에도 투자를 아끼지 않고 있다. 특히 고가의 차량일수록 일반 청음실에서 느낄 수 있는 높은 수준의 음향 시설을 갖추려고 한다. 이러한 현상은 차량의 모델에 국한되지 않는다. 요즘 인기가 많은 RV차량에서도 고객들이 수준 높은 음질을 만끽할 수 있도록 제조사들은 고품질의 음향 시스템을 탑재하는 움직임을 발견할 수 있다. 그러나 고품질 음향시스템은 대부분 고가의 부품을 필요로 하는 관계로, 이는 필연적으로 자동차 판매가의 증대를 야기한다. 따라서 비교적 저가의 음향시스템을 이용하더라도 고객이 만족해 할 수 있는 음질을 구현하는 차량 내 음향 시스템 구축의 필요성이 대두되었다. 즉, 인간의 청각적 특성이 고려된 객관적인 자동차 '오디오 시스템 성능 측정 지표' 및 튜닝 방법에 관한 연구가 필요하다. 본 논문에서는 RV차량의 오디오 시스템의 성능을 평가하고 개선하기 위해 인간의 청각적 특성이 고려된 오디오 신호의 특성을 사물인터넷(IoT) 센서를 이용해 측정하고 분석하였다. 분석 결과 사람에게 민감한 대역의 높은 에너지지가 있는 점은 인지에 대한 비중을 높일 수 있으나, 해당 대역만 강조된 경우에는 성가심을 유발할 수 있는 것으로 나타났다. 그리고 왜곡된 주파수 평탄도는 음질에 나쁜 영향을 줄 수 있어 주파수 응답의 평탄화를 필요로 한다는 점을 발견할 수 있었다.

• Structural Monitoring and Maintenance
• /
• 제1권1호
• /
• pp.131-157
• /
• 2014

Special track systems used to divert a train to other directions or other tracks are generally called 'railway turnout'. A traditional turnout system consists of steel rails, switches, crossings, steel plates, fasteners, screw spikes, timber bearers, ballast and formation. The wheel rail contact over the crossing transfer zone has a dip-like shape and can often cause detrimental impact loads on the railway track and its components. The large impact also emits disturbing noises (either impact or ground-borne noise) to railway neighbors. In a brown-field railway track where an existing aged infrastructure requires renewal or maintenance, some physical constraints and construction complexities may dominate the choice of track forms or certain components. With the difficulty to seek for high-quality timbers with dimensional stability, a methodology to replace aged timber bearers in harsh dynamic environments is to adopt an alternative material that could mimic responses and characteristics of timber in both static and dynamic loading conditions. A critical review has suggested an application of an alternative material called fibre-reinforced foamed urethane (FFU). The full-scale capacity design makes use of its comparable engineering characteristics to timber, high-impact attenuation, high damping property, and a longer service life. A field trial to investigate in-situ behaviours of a turnout grillage system using an alternative material, 'fibre-reinforced foamed urethane (FFU)' bearers, has been carried out at a complex turnout junction under heavy mixed traffics at Hornsby, New South Wales, Australia. The turnout junction was renewed using the FFU bearers altogether with new special track components. Influences of the FFU bearers on track geometry (recorded by track inspection vehicle 'AK Car'), track settlement (based on survey data), track dynamics, and acoustic characteristics have been measured. Operational train pass-by measurements have been analysed to evaluate the effectiveness of the replacement methodology. Comparative studies show that the use of FFU bearers generates higher rail and sleeper accelerations but the damping capacity of the FFU help suppress vibration transferring onto other track components. The survey data analysis suggests a small vertical settlement and negligible lateral movement of the turnout system. The static and dynamic behaviours of FFU bearers appear to equate that of natural timber but its service life is superior.

• 대한후두음성언어의학회지
• /
• 제17권1호
• /
• pp.43-48
• /
• 2006

Background and Objectives: Countertenors who can produce higher vocal pitch like female classical singer's voice and use both modal and falsetto register. This study was conducted to study phonatory characteristics between modal and falsetto register of the countertenor. Materials and Methods: A male countertenor who had 8 years of experience was examined using a videostroboscopy and his voice was analyzed using aerodynamic measures; fundamental frequency(F0), Mean air flow rate(MFR), intensity(SLP), subglottal air pressure(Psub) with phonatory function analyzer(Nagashima) and acoustic measures; jitter, shimmer, HNR, closed quotient(CQ) using a Electro-glottography(EGG) of Lx. Speech Studio(Laryngoscope, Ltd, UK) and voice range profile of CSL(Kay elemetrics). Results: In the stroboscopy finding, the longitudinal length of vocal folds was increased at the falsetto register and the upper margin of vocal folds vibrated with incomplete closure of true vocal folds. In aerodynamic analysis, intensity was same at the modal and falsetto register. However, MFR, Psub, MPT were higher at the falsetto register. In the electroglottographic analysis, closed quotient(CQ) at the modal register was high and also much higher at the high-pitch falsetto than at the loud falsetto. In the VRP, intensity was similar though F0 was different between modal and falsetto register. Conclusion: It implied that countertenor could produce powerful voice quality by increasing of respiratory pressure and respiratory volume though glottal closure was incomplete. In addition, no change of EGG waveform, similar voice range with alto was observed.

• Journal of Mechanical Science and Technology
• /
• 제18권2호
• /
• pp.185-192
• /
• 2004

The aeroacoustic characteristics of a centrifugal fan for a vacuum cleaner and its noise reduction method are studied in this paper. The major noise source of a vacuum cleaner is the centrifugal fan. The impeller of the fan rotates at over 30000 rpm, and generates very high-level noise. It was revealed that the dominant noise source is the aerodynamic interaction between the rotating impeller and stationary diffuser. The directivity of acoustic pressure showed that most of the noise propagates backward direction of the fan-motor assembly. In order to reduce the high tonal sound generated from the aerodynamic interaction, unevenly pitched impeller and diffuser, and tapered impeller designs were proposed and experiments were performed. Uneven pitch design of the impeller changes the sound quality while the overall sound power level (SPL) and the performance remains similar. The effect of the tapered design of impeller was evaluated. The trailing edge of the tapered fan is inclined. This reduces the flow interaction between the rotating impeller and the stationary diffuser because of some phase shifts. The static efficiency of the new impeller design is slightly lower than the previous design. However, the overall SPL is reduced by about 4 dB(A). The SPL of the fundamental blade passing frequency (BPF) is reduced by about 6 dB (A) and the 2$\^$nd/ BPF is reduced about 20 dB (A). The vacuum cleaner with the tapered impeller design produces lower noise level than the previous one, and the strong tonal sound was dramatically reduced.

• 해양환경안전학회:학술대회논문집
• /
• 해양환경안전학회 2007년도 춘계학술발표회
• /
• pp.109-113
• /
• 2007

요트에서는 가벼운 선체에 비해 고성능의 엔진을 탑재하게 되므로 엔진에서 발생하는 소음이 승조원 및 여객에 미치는 영향은 매우 크다. 최근에는 국내에서도 크루즈요트의 생산이 시도되고 있지만, 선박의 성능과 함께 기관소음의 차단기술이 구매자의 요구에 부응하지 못하고 있는 실정이다. 이와 같이 선실의 소음이 구매를 결정하는 중요한 척도로 되고 있지만, 메인엔진의 소음을 차단하기 위한 대책 이 부족한 형편이다. 그러나 최근에 발전되고 있는 모니터링설비와 지능제어시스템을 이용하면, 주 엔진의 주변을 고효율의 흡음벽으로 차단하여 기관실의 소음을 개선할 수 있다. 본 연구에서는 소음을 흡수할 수 있는 흡음벽의 성능을 높이기 위해 헬름홀츠 공명기의 원리를 적용에 대하여 연구하였다.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2007년도 추계학술대회논문집
• /
• pp.939-942
• /
• 2007

Vacuum cleaner is a close life product that can remove various dusts from our surroundings. However well vacuum cleaner clean our environments, many people are looking away from it, due to its loud noise. Its noise causes a big trouble in the usual life, for example, catch calls, TV watching and discussing etc. To reduce these inconveniences, noise reduction methods and systematic design of low noise vacuum cleaner are studied in this paper. At first, sound quality investigation is performed to get the noise level and quality that make people TV watching and catch calls available. Based on the European and domestic customer SQ survey result, sound power, peak noise level and target sound spectrum guideline are studied and introduced. As a second, precise product sound spectrums are designed into each part based on the sound quality result. Fan-motor, brush, mainbody, cyclone spectrums are decided to get the final target sound based on the contribution level. Fan-motor is the major noise source of vacuum cleaner. Specially, its peak sound, RPM peak and BPF Peak, cause the people nervous. To reduce these peak sounds, high rotating impeller and diffuser are focused due to its interaction. A lot of experimental and numerical tests, operation points are investigated and optimization of flow path area between diffusers is performed. As a bagless device, cyclones are one of the major noise sources of vacuum cleaner. To reduce its noise, previous research is used and adopted well. Brush is the most difficult part to reduce noise. Its noise sources are all comes from aero-acoustic phenomena. Numerical analysis helps the understanding of flow structure and pattern, and a lot of experimental test are performed to reduce the noise. Gaps between the carpet and brush are optimized and flow paths are re-designed to lower the noise. Reduction is performed with keeping the cleaning efficiency and handling power together and much reduction of noise is acquired. With all above parts, main-body design is studied. To do a systematic design, configuration design developments technique is introduced from airplane design and evolved with each component design. As a first configuration, fan-motor installation position is investigated and 10 configuration ideas are developed and tested. As a second step, reduced size and compressed configuration candidates are tested and evaluated by a lot of major factor. Noise, power, mass production availability, size, flow path are evaluated together. If noise reduction configuration results in other performance degrade, the noise reduction configuration is ineffective. As a third configuration, cyclones are introduced and the size is reduced one more time and fourth, fifth, sixth, seventh configuration are evolved with size and design image with noise and other performance indexes. Finally we can get a overall much noise level reduction configuration. All above investigations are adopted into vacuum cleaner design and final customer satisfaction tests in Europe are performed. 1st grade sound quality and lowest noise level of bagless vacuum cleaner are achieved.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2010년도 춘계학술대회 논문집
• /
• pp.48-48
• /
• 2010

Sound quality and NVH-issues(Noise, Vibration and Harshness) of vehicles has become very important for car manufacturers. It is interpreted as among the most relevant factors regarding perceived product quality, and is important in gaining market advantage. The general sound quality of vehicles was gradually improved over the years. However, today the development cycles in the automotive industry are constantly reduced to meet the customers' demands and to react quickly to market needs. In addition, new drive and fuel concepts, tightened ecological specifications, increase of vehicle classes and increasing diversification(increasing market for niche vehicles), etc. challenge the acoustic engineers trying to develop a pleasant, adequate, harmonious passenger cabin sound. Another aspect concerns the general pressure for reducing emission and fuel consumption, which lead to vehicle weight reductions through material changes also resulting in new noise and vibration conflicts. Furthermore, in the context of alternative powertrains and engine concepts, the new objective is to detect and implement the vehicle sound, tailored to suit the auditory expectations and needs of the target group. New questions must be answered: What are appropriate sounds for hybrid or electric vehicles? How are new vehicle sounds perceived and judged? How can customer-oriented, client-specific target sounds be determined? Which sounds are needed to fulfil the driving task, and so on? Thus, advanced methods and tools are necessary which cope with the increasing complexity of NVH-problems and conflicts and at the same time which cope with the growing expectations regarding the acoustical comfort. Moreover, it is exceedingly important to have already detailed and reliable information about NVH-issues in early design phases to guarantee high quality standards. This requires the use of sophisticated simulation techniques, which allow for the virtual construction and testing of subsystems and/or the whole car in early development stages. The virtual, testing is very important especially with respect to alternative drive concepts(hybrid cars, electric cars, hydrogen fuel cell cars), where complete new NVH-problems and challenges occur which have to be adequately managed right from the beginning. In this context, it is important to mention that the challenge is that all noise contributions from different sources lead to a harmonious, well-balanced overall sound. The optimization of single sources alone does not automatically result in an ideal overall vehicle sound. The paper highlights modern and innovative NVH measurement technologies as well as presents solutions of recent NVH tasks and challenges. Furthermore, future prospects and developments in the field of automotive acoustics are considered and discussed.

• 말소리와 음성과학
• /
• 제16권2호
• /
• pp.49-58
• /
• 2024

본 연구에서는 정상음성사용자를 대상으로 음성검사를 위한 고가의 음성 녹음 장비인 Computerized Speech Lab(CSL) 대신 스마트폰에 적용 가능한 단일지향성 유선 핀마이크(WIRED), 스마트폰의 자체 내장 무지향성 마이크(SMART), 블루투스 무선 이어폰인 갤럭시 버즈2 프로(WIRELESS)로 녹음된 음성샘플의 음향학적 측정치를 비교하고자 하였다. 연구대상은 최근 3개월 이내 호흡기 질환으로 이비인후과에 내원한 적이 없는 정상성인 40명(남 12명, 여 28명)이었으며, 소음이 통제된 방음 부스에서 모음 /아/ 연장 발성(4초) 과제와 '산책' 문장, '가을' 문단 읽기 과제를 네 가지의 기기로 동시에 녹음하였다. 4종의 샘플들에 대하여 CSL 녹음을 기준으로 동기화 작업을 진행하였으며, MDVP와 ADSV, VOXplot 프로그램을 이용하여 분석하였다. 연구 결과, F0, shimmer, noise-to-harmonic ratio를 제외한 다른 변수들에서 유의미한 차이가 있었다. 특히 SR_V, SR_S, CSID_V, CSID_S, AVQI의 경우 CSL에 비해 WIRED의 CSID_V, CSID_S, AVQI 중증도가 낮았던 반면, SMART에서는 높게 나타났다. SR_V, SR_S의 경우 반대의 경향이 나타났으며, WIRELESS는 과제에 따라 다른 경향이 있었다. CSL과 다른 마이크 유형들은 동일한 변수 간에는 모두 양의 상관관계를 보였으며, F0와 CPP_V가 모든 유형에서 공히 강한 양의 상관관계를 보였다. ICC 또한 F0와 CPPV가 모두 0.9 이상으로 가장 높았다. 본 연구에서 사용된 마이크를 음향학적 분석을 위한 녹음 도구로 사용할 때, F0와 CPP_V의 경우 신뢰도 높은 분석 변수로 마이크 유형과 무관하게 포함할 수 있고, SR, CSID, AVQI의 경우 마이크 유형에 따라 분석 및 해석에 주의를 기울일 필요가 있을 것으로 판단된다.

• 한국음향학회지
• /
• 제30권4호
• /
• pp.197-206
• /
• 2011

본 논문에서는 다채널 스피커를 사용하는 음향 시스템에서의 가상 음원 생성 알고리즘을 제안하고 있다. 영상 신호의 표준은 보다 높은 해상도와 더 넓은 시야각을 제공하는 HD급이나 그 이상의 UHD급 등의 규격이 점차 상용화되고 있다. 그에 따라 음향 신호 또한 더 넓어진 음향 공간에서의 효과적인 음원 생성에 대한 필요성이 증가하고 있다. 기존의 스테레오 스피커 시스템으로는 원하는 사운드 효과를 재생하는데 한계를 가질 수밖에 없기 때문에, 여러 개의 스피커를 사용한 다양한 배치의 다채널 스피커 시스템이 제안되고 있다. 그러나 다수의 스피커를 사용한 시스템에서 기존의 사운드 패닝 알고리즘과 같은 가상 음원 생성 기술을 그대로 적용할 경우, 불연속적인 방향성 문제나 음색 열하 등의 또다른 문제가 발생할 수 있다. 이를 해결하기 위하여 임의의 배치의 다채널 스피커 시스템에서 적용 가능한 벡터 기반의 가상 음원 생성 알고리즘을 제안하였다. 제안된 알고리즘은 벡터 기반의 게인 조절 함수를 이용하여 음원의 방향감을 쉽고 효과적으로 생성할 수 있으며, 대칭 혹은 비대칭의 다채널 스피커 배치에 대해서 모두 적용 가능하다. 기존에 잘 알려진 VBAP와 MDAP의 레벨 패닝 방법과 의 청취 비교 실험을 통하여 보다 정확한 패닝 성능을 유지할 수 있는 것으로 확인되었다.