잡음제거 기능을 갖춘 시-청각 단서 제공 읽기 훈련 프로그램

방동혁,강현덕,길세기,이상민 한국재활복지공학회 2008 재활복지공학회논문지 Vol.2 No.1

In this paper, we introduce a reading training program offering visual-auditory cue with noise cancellation function (RT program) developed by us. The RT program provides some training sentences with visual-auditory cues. Motor speech disorder patients can use the visual and/or auditory cues for reading training. To provide convenient estimation of training result, we developed a noise cancellation algorithm. The function of the algorithm is to remove noise and auditory-cues which are recorded with reading speech at the same time while patient read the sentences in PC monitor. In addition, we developed a function for finding out the first starting time of reading sound after a patient sees a sentence and begins to read the sentence. The recorded speeches are acquired from six people(three male, three female) in four noisy environments (interior noise, white noise, car interior noise, babble noise). We evaluated the timing error for starting time between original recorded speech and processed speech in condition of executing noise cancellation function and not executing. The timing error was improved as much as 4.847±2.4235[ms] as the effect of noise cancellation. It is expected that the developed RT program helps motor speech disorder patient in reading training and symptom evaluation.

교통환경 정온화를 위한 도로 소음의 측정 및 ANC시스템에의 적용 특성 고찰

문학룡(Hak-ryong Moon),손진근(Jin-geun Shon) 대한전기학회 2013 전기학회논문지 P Vol.62 No.3

Noise problem that occurs on the road is raising a lot of problems in the economic, social and environmental aspects. The objective of this paper is to propose ANC(active noise cancellation)-based road traffic noise reduction algorithm-model which can reduce noise by generating frequency opposed to noise sources to improve and complement the problem that existing physical form of a noise barrier. In this paper, we measured the noise characteristic from collection of two difference car noise also ANC simulation has been performed by using road traffic noises input. In order to compare the control performance, we performed noise reduction simulation of ANC by filtered-X LMS algorithm and delayed control signal injection. As a result of this simulation, we confirmed that convergence performance and noise decrease effect to the filtered-X LMS algorithm by inputting the road traffic noise.

Active Noise Cancelling 이어폰이 소음환경에서 선호청취음량에 미치는 영향

나우성,김건우,정성도,이재욱,정재윤,서명환 대한이비인후과학회 2012 대한이비인후과학회지 두경부외과학 Vol.55 No.7

Background and Objectives Active noise cancelling (ANC) is a technology that can reduce external noise by producing a signal that is similar to noise but different in that it has an opposite phase to noise. Nowadays ANC has become an important technology in the field of hearing aids, but many studies have not focused on the effect of ANC of earphones when listening to portable music players. In this study, we aimed to evaluate whether ANC earphones can effectively reduce external noise and lower the preferred listening level. Subjects and Method Three different earphones (Ear-canal, On-the-ear, Covering-the-ear) were tested in three different noise environments. Nine participants were tested in 10 experiments. First, through the real ear measurement (REM) system, we evaluated the differences in sound pressure level when the ANC was either turned on or off. Second, we evaluated the effects of ANC on Preferred Listening Level (PLL) for participants listening to the same song with different earphones. Through the REM system, we evaluate the level of sound pressure level when participants controlled the volume and felt most comfortable with the volume level. Results All three types of earphones showed statistically significant effects on noise reduction when ANC was turned on. The noise reduction effect was most prominent with the Ear-canal earphone. All three types of earphones also showed statistically significant effect on PLL reduction. Conclusion ANC earphones may be helpful in noise reduction and preventing noise induced hearing loss when listening to music in noisy environments. Among the three types of earphones, Ear-canal earphone seems to be the most effective in noise reduction.

치과 의료 환경에서 발생하는 소음에 대한 주관적 평가 및 노이즈 캔슬링 이어폰의 차음 효과 비교

이민아,김익환,이태양,박원서,송제선 대한치과의사협회 2022 대한치과의사협회지 Vol.60 No.12

Purpose: Various devices such as dental handpieces, ultrasonic scalers, and aspirators exist in the dental clinic, and they generate noise with high decibel levels in a complex way. Through this study, we survey the discomfort and hearing changes on patients and dental staff, and compare and analyze the sound insulation effect of each noise cancelling product for vari - ous noises. Materials and Methods: This study is a multi-faceted evaluation of noise generated in the dental treatment. First, patients and dental staffs were surveyed through the Gallup Korea Research Institute. Afterwards, subjective evaluations of various noise cancelling earphones for dental noises were conducted by VAS scales. Results: In this study, more than 50% of patients, dentists, and dental hygienists feel uncomfortable about dental noise, and more than 70% of the respondents say that they had interrupted in communication due to noise. In both the dentist and non-dentist groups, when noise-cancelling earphones were used for high-speed and low-speed handpieces and suction noise, a decrease in VAS value was confirmed. Regarding the scaler noise, the increase or decrease of the VAS value was different depending on the products. Conclusion: The results of this study indicate that noise generated in a dental treatment can cause emotional discomfort to both patients and dental staff, and both are aware of the possibility of hearing impairment. And it is necessary to consider the sound isolation device optimized for each noise.

도로교통소음 저감을 위한 Active Noise Cancellation System 적용 및 평가

김도완,김연주,이상염,문성호,안덕순 한국방재학회 2014 한국방재학회논문집 Vol.14 No.6

The objective of this study is to evaluate ANC(Active Noise Cancellation) system composed of the prediction model for SPL(SoundPressure Level) in accordance with the targeted frequencies. The ANC system and prediction model were developed in previousresearch. Its technical skills were based on ISO 9613. Moreover, we utilized the LimA Predictor to identify the accurate results of trafficnoise obtained from measurement and prediction at the receiver points. To measure the traffic noise occurred at the road, the measurementmethod of Pass-by was conducted. This paper is focused on the reduction and superposition of sound longitudinal wave.:The theory of this paper is based on International Organization for Standardization 9613. In the frequency analysis, we conductedCPB(Constant Percentage Bandwidth) Analysis to determine the traffic noise properties related to the frequencies. In the previousresearch, FFT(Fast Fourier Transform) Analysis was used to eliminate the engine noise from the friction noise between the road andtire. The LimA Predictor was utilized to simulate the noise propagation and confirm the noise level. Also, the basic wave theory wasapplied to conduct the reduction of traffic noise from the prediction noise level. The study has shown that the reduction and superpositioneffect was almost from 11dB(A) to 22dB(A) when the superposition of waves is perfectly applied and the ANC system canbe completely compatible with the practical traffic noise. The effect of sound wave reduction using ANC system at the relatively highfrequencies was better than the low frequencies. Furthermore the errors of measurement and prediction were small at the range of highfrequencies. 본 연구는 실제 도로에서 발생하여 수음점으로 전달되는 도로교통소음을 측정한 뒤, 이전 연구에서 개발한 도로교통소음 예측 모델을ANC시스템에 적용하여 적합성을 판단하였고 이를 통해 음향 감쇠효과를 어느 정도 발휘할 수 있을지 평가하는 것을 목적으로 수행되었다. 이전 연구에서는 노면과 타이어사이의 마찰소음도를 파악하기 위해 고속푸리에 변환(FFT, Fast Fourier Transform)분석을 활용하였지만, 본 연구에서는 제규격 ISO 9613-2의 음향 방사효과를 적용하였으며 ANC시스템에 도입되는 예측소음도와 측정소음도를 대조하는 과정에서 예측결과와 측정결과의 정확성을 판단하기 위해 음향감쇠의 기본적인 파동 이론인 LimA Predictor를 활용하였다. 또한 본 연구는 종방향 음파의 음향 중첩을 기반으로 결론적으로 주파수 별 음압 예측모델이 ANC시스템에 적용되어 서로 다른 음원에서 정확하게 음파를 중첩시킬 수 있는 경우 음향의 감쇠효과는 최대 22dB(A)부터 최소 11dB(A)까지 발휘될 수 있음을 밝혔고, 상대적으로 고주파수보다 저주파수에서 ANC 시스템을 도입한 음향 감쇠효과가 크게 나타났으며, 고주파수 영역 대에서는 측정결과와 예측결과 사이의 오차가 더 작은 것으로 파악되었다.

능동 소음 제어를 이용한 자동차 실내 타이어 공명음의 저감

백지선,유진환,이상권,윤영삼,이재훈,염기호,황성욱 한국자동차공학회 2022 한국 자동차공학회논문집 Vol.30 No.10

This study proposesa new method for active noise cancellation(ANC) of cavity noise of a tire. A general method for ANC of road noise is to use several accelerometers for acquirement of reference signals. Cavity noise of tire is caused by the resonance of tire cavity mode. Resonance frequencies of tire cavity are determined by the cavity structure of tire. Therefore, harmonic sinusoidal signals can be used for reference signals. However,resonance frequencies could be varied due to small change of tire cavity during driving of a car. For the overcome of this variation, adaptive filter of ANC system was designed and applied to the ANC of a cavity noise. The proposed method didnot need accelerometers for the ANC of cavity noise and practically was applied to the ANC of cavity noise of a tire in a car. Cavity noise of a test was attenuated to 3-5dBA and effect of reduction was similar to passive method like resonant type tire.

디지털 보청기에서 마이크로폰 어레이를 이용한 잡음제거

방동혁(Dong-hyeouck Bang),길세기(Se-kee Kil),강현덕(Hyun-deok Kang),윤광섭(Gwang-sub Yoon),이상민(Sang-min Lee) 대한전기학회 2009 전기학회논문지 Vol.58 No.4

In this paper, a noise cancellation-method using microphone array for digital hearing aids is proposed. The microphone array is located around the ear of a dummy. Speech sound is generated from the forward speaker positioned in the front of the dummy and noise sound is generated from the backward speaker. The speech and noise are mixed in the air space and entered into the microphones. VAD(voice activity detector) and ANC(adaptive noise cancellation) methods were used to eliminate noise in the sound of the microphones. 10 two-syllable words and 4 sentences were used for speech signals. Babble and car interior noise were used for noise signals. The performance of the proposed algorithm was evaluated by SNR(signal-to-noise ratio) and PESQ-MOS(perceptual evaluation of speech quality-mean opinion score). In babble noise condition, SNR was improved as much as 7.963±1.3620㏈ and 3.968±0.6659㏈ for words and sentences respectively. In the case of car interior noise, SNR was improved as 10.512±2.0665㏈ and 6.000±1.7642㏈ for words and sentences respectively. PESQ-MOS of the babble noise was improved as much as 0.1722±0.0861 score for words and 0.083±0.0417 score for sentences. And PESQ-MOS of the car interior noise was improved as 0.2661±0.0335 score and 0.040±0.0201 score for words and sentences respectively. It is verified that the proposed algorithm has a good performance in noise cancellation of microphone array for digital hearing aids.

도로분야 소음 저감을 위한 국내외 ANC 기술수준 및 WBT 분석

임유진(You-Jin Lim),문학룡(Hak-Ryong Moon),변상철(Sang-Cheal Byun),강원평(Won-Pyoung Kang) 한국소음진동공학회 2015 한국소음진동공학회 학술대회논문집 Vol.2015 No.4

Noise generated from the road is one of factors that degrade the quality of life for people. Installing a barrier is an alternative method for reducing road transportation noise. But it has many limitations like the yellowing phenomenon and the surrounding landscape. In order to solve this problem we propose applying active noise cancelation(ANC) to road. We analyze the technical trend and WBT of active noise cancelation in Korea and internationally. The results of study indicates that active noise cancelation has been applied to various fields such as vehicles, airplanes, audio equipment and so on. It needs further research to apply active noise cancelation to the road in order to provide a comfortable lifestyle foe civilians.

도로 기하구조에 따른 차량 Microphone 위치별 소음 영향 분석

문학룡,한대철,강원평 한국도로학회 2013 한국도로학회논문집 Vol.15 No.4

PURPOSES: The purpose of study is to understand the characteristic of driving noise from the front and rear tire for effective active noise cancellation application. METHODS : As literature review, noise measurement methods were reviewed. Noise measurement conducted at three kind of section by road slope using CPX(Close Proximity Method). Noise data was compared by total sound pressure level and 1/3 octave band frequency sound pressure level. Also, each section was compared by T-test using SPSS. RESULTS : In the case of the uphill section, it was shown that the sound pressure level of the front tire at Sugwang-Ri and Sinchon-RI sections was higher than that of the rear tire in low and high frequency band. In the case of high slope section of Sangsaek-Ri, the sound pressure level of the front tire was higher than that of the rear tire in high frequency. Also, in the case of the downhill section, it was shown that the sound pressure level of the front tire at Sugwang-Ri and Sinchon-RI sections was higher than that of the rear tire in low frequency band. However, the sound pressure levels of both the front and rear tires were approximately the same in the high slope section of Sangsaek-Ri. The result of T-test showed that total sound pressures of the front and rear tires were not different from each other in the case of high slope and high speed. CONCLUSIONS: Road slope was not an important variable for effective active noise cancellation.

Common Mode Noise Reduction for an LLC Resonant Converter by Using Passive Noise Cancellation

Younggon Ryu,Sungnam Kim,Geunseok Jeong,Jaesu Park,Duil Kim,Jongwook Park,Jingook Kim,Ki Jin Han 한국전자파학회JEES 2015 Journal of Electromagnetic Engineering and Science Vol.15 No.2

This paper describes the application of a passive noise cancellation method to a prototype inductor-inductor-capacitor (LLC) resonant converter by placing a compensation winding in a transformer to reduce common mode noise. The connection method for the compensation winding is investigated. A circuit analysis is implemented for the displacement currents between the primary and secondary windings in the transformer. The analyzed displacement currents are verified by performing a circuit simulation and a proper compensation winding connection that reduces common mode noise is found. The measurement results show that common mode noise is reduced effectively up to 20 dB in the 1 to 7 MHz frequency region for the prototype LLC resonant converter by using the proposed passive noise cancellation method.