• Title, Summary, Keyword: Speaker pressure level

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Experimental study of the sound quality performance and improvement of magnetic fluid speaker (자성유체 스피커의 음질 성능 및 향상에 관한 실험적 연구)

  • Lee, Moo-Yeon
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.15 no.12
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    • pp.6993-6997
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    • 2014
  • The aim of this study was to experimentally investigate the sound quality characteristics, such as sound deflection, sound pressure level and frequency characteristics of a magnetic type speaker in an anechoic chamber to overcome the sound quality and voice-coil temperature problems. To accomplish this, the sound quality performance of the magnetic type speaker was tested according to the magnetic fluid amount and magnetic field intensity. The sound deflection, sound pressure level, and frequency characteristics were measured using the Smarrt program. As a result, at a magnetic fluid amount of 2.4 ml, the sound deflection and the sound pressure level of the magnetic type speaker were enhanced by comparing with those of the general type speaker. The frequency characteristics and the sound pressure level of the magnetic type speaker were enhanced greatly with increasing magnetic field intensity from 8.06 mT to 9.10 mT. In addition, the sound deflection of the magnetic type speaker was 0.01% lower than that of the general type speaker.

Multidisciplinary Design Optimization for Acoustic Characteristics of a Speaker Diaphragm (스피커 진동판의 음향특성 다분야통합최적설계)

  • Kim, Sung-Kuk;Lee, Tae-Hee;Lee, Surk-Soon
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.763-766
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    • 2004
  • Recently, various acoustic artifacts that contains speaker have been produced such as cellular phone. Speaker consists of diaphragm generating sound and coil vibrating diaphragm. Generally, good speaker means that it has a wide frequency range, high output power rate to input power and flat sound pressure level in specified frequency range. Acoustic characteristic was estimated through the experiment and computer simulation, or sound power was controlled with acoustic sensitivity in a natural frequency range fer last decade. However, the flatness of sound pressure level has not been considered to enhance the sound quality of a speaker. Tn this study, a method for speaker design is proposed for a good acoustic characteristic, which is flatness of SPL(sound pressure level) and wideness between the first and second natural frequency. SYSNOISE is used fer acoustic analysis and ANSYS is used for harmonic response analysis and modal analysis. Optimization for acoustic characteristics of a speaker diaphragm is performed using ModelCenter. All analyses are done within a frequency domain. And we confirm that the experimental and computational simulations have similar trend.

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High Performance Piezoelectric Microspeakers and Thin Speaker Array System

  • Kim, Hye-Jin;Koo, Kun-Mo;Lee, Sung-Q;Park, Kang-Ho;Kim, Jong-Dae
    • ETRI Journal
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    • v.31 no.6
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    • pp.680-687
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    • 2009
  • This paper reports on an improved piezoelectric microspeaker with a high sound pressure level of 90 dB, a total harmonic distortion of less than 15%, and coherence higher than 0.9. The fabricated Pb(Zr,Ti)$O_3$ (PZT) microspeakers have a thickness of only 1 mm including the speaker frame and an active area of 18 mm${\times}$20 mm. To achieve higher sound pressure and lower distortion, the PZT piezoelectric microspeaker has a well-designed speaker frame and a piezoelectric diaphragm consisting of a tilted PZT membrane and silicone buffer layer. From the simulation and measurement results, we confirmed that the silicon buffer layer can lower the first resonant frequency, which enhances the microspeaker's sound pressure at a low frequency range and can also reduce useless distortion generated by the harmonics. The fabricated PZT piezoelectric microspeakers are implemented on a multichannel speaker array system for personal acoustical space generation. The output sound pressure at a 30 cm distance away from the center of the speaker line array is 15 dB higher than the sound pressure at the neighboring region 30 degrees from the vertical axis.

A New Type Speaker Utilizing a Magneto-rheological Fluid Diaphragm (자기유변유체 다이어프램을 이용한 새로운 타입의 스피커)

  • Park, Jhin Ha;Yoon, Ji Young;Kim, Seon Hye;Lee, Tae Hoon;Lee, Soo Hyuk;Choi, Seung Bok
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.27 no.2
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    • pp.182-188
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    • 2017
  • In this work, a new type speaker which features various resonant frequencies is proposed utilizing a magneto-rheological (MR) fluid and its performance is evaluated in terms of the change of the field-dependent sound pressure level. In order to achieve this goal, a whole concept of the speaker system is firstly discussed and subsequently a controllable diaphragm is made using MR fluid whose rheological properties such as viscosity are controllable by the magnitude of magnetic field. Then, the proposed speaker system consisting of the inner structure and the squeeze mode type of MR diaphragm is established in an anechoic room The effectiveness of the proposed speaker system is experimentally evaluated at two different conditions; with and without the magnetic field. It is shown from experimental tests that the sound pressure level at different sound source can be controlled which is not able to achieve using one conventional speaker system.

Microstructures and Electrical Properties of PSN-PZT Ceramics for Piezoelectric Speaker (압전 스피커 응용을 위한 PSN-PZT계 세라믹스의 미세구조 분석 및 전기적 특성 평가)

  • Kim, Sung-Jin;Kweon, Soon-Yong
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.32 no.2
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    • pp.110-115
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    • 2019
  • $Pb(Sb_{0.5}Nb_{0.5})_x(Zr_{0.51}Ti_{0.49})_{1-x}O_3$ (abbreviation: PSN-PZT) ceramics were synthesized, using conventional bulk ceramic processing technology, with various PSN doping contents. The maximum density of PSN-PZT was 97% of the theoretical density in the samples sintered at $1,250^{\circ}C$. The maximum values of the piezoelectric properties achieved using the conventional processes were: $k_p$ of 0.625, $d_{33}$ of 531 pC/N, and $g_{33}$ of $33mV{\cdot}m/N$. Finally, we fabricated a piezo-speaker with the optimized PSN-PZT ceramics. The SPL of the speaker was measured at a distance of 1 m, with a driving voltage of $40V_{rms}$ in the frequency range of ~300 Hz to 9 kHz. The measured $SPL_{max}$ was at a very high level (95 dB), which was superior in quality in comparison with those of other commercial products.

Analysis of the Relation Between Micro-Speaker with the Back Holes and the Ducted Speaker-System (후면기공을 갖는 마이크로스피커와 덕트형 스피커시스템사이의 연관성 해석)

  • Rhee, Esther;Oh, Sei-Jin
    • The Journal of the Acoustical Society of Korea
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    • v.26 no.3
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    • pp.115-122
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    • 2007
  • In this study, the property and the structure of micro-speaker had been firstly shown to be treated as a ducted speaker-system, which was consisted of the unit and the ducted enclosure. With the decrease of total hole area. the resonance frequency of micro-speaker was decreased due to increasing the stiffness or reducing the compliance. The behavior of resonance frequency relative to the total hole area was exactly agreed with that of the square root of compliance. With decreasing the total hole area. the effective chamber volume was increased, but the reference sound pressure level was exponentially reduced in the low and middle frequency range.

Design of Low Frequency Flat Speaker by Piezofilm (Piezofilm 을 이용한 저주파 평면 스피커의 설계)

  • Hwang, Joon-Seok;Lee, Sung;Kim, Seung-Jo
    • Proceedings of the Korean Society For Composite Materials Conference
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    • pp.191-194
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    • 2000
  • In this study, experimental verification of performance of flat speaker has been conducted. The piezofilm (PVDF) actuator has been designed to prevent the distortion of sound and make the frequency response of radiated sound flat. The electrode pattern of piezofilm actuator is optimized to satisfy the design objective. The formulation of design method is based on the coupled finite element and boundary element method and electrode pattern is optimized by genetic algorithm. The flat speaker with optimized piezofilm actuator has been manufactured. The sound pressure level at the distance of 50cm is measured using microphone and compared with the result of numerical simulation.

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Subjective Evaluation of Stage Acoustics with the alteration of the sound pressure level of reverberation. (잔향음압의 변화에 대한 무대음향의 주관적 평가)

  • Kim, Young-Sun;Jeong, Jeong-Ho;Jeon, Jin-Yong
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.742-742
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    • 2003
  • This study is about the effect of the sound pressure level of reverberation on stage acoustics. There are several electro-acoustics systems to enhance the room acoustics of concert hails but not many studies on the stage acoustics for the musicians who plays on the stages. To investigate the effect of reverberation on stage acoustics, the reverberation time of a test room has been controlled through a 4 channel speaker system, and the preferred reverberation level has been selected by performing musicians. As a result, the sound pressure level of reverberation seems to affect the perception of stage acoustics which motivates musicians' performances.

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An Experimental Study on the Optimistic Recognition Level of Public Address System as a Soundscape Application Facility (사운드스케이프 적용을 위한 옥외 P.A. 시스템의 적정 인지레벨에 관한 실험적 연구)

  • Song, Min-Jeong;Jang, Gil-Soo
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.17 no.11
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    • pp.1050-1055
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    • 2007
  • P.A.(public address) system is considered as an useful active soundscape appliance which can gives a place identity and vitality by introducing conventional musics, environmental musics, bird singing sounds etc. In this study, the main aim is to know the optimistic distance from the speaker and sound pressure level range of introducing sound. So, the sound pressure level of P.A. system due to distances were measured and subjects' responses with level variations were checked. The main results are as follows. Level range from 64 dB to 71 dB is comfortable for subjects. And the optimal level of introducing sound is related with sound source characteristics. The results of this study could be used for street furniture location design and P.A. system output level.

Study on Cooling System Characteristics of 400W Active Speaker (400W급 액티브 스피커의 냉각시스템 특성에 관한 연구)

  • Seo, Jae-Hyeong;Bang, You-Ma;Lee, Moo-Yeon
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.16 no.12
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    • pp.8140-8146
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    • 2015
  • The objective of this study is to experimentally investigate the cooling performance characteristics with the consideration of the temperature variations of the enclosure of the 400W ferrofluid active speaker having both woofer and amplifier heat sinks. In order to do this, the heat sinks for both woofer and amplifier was designed ant applied to 400W ferrofluid active speaker. As a result, the cooling performance of the developed 400W ferrofluid active speaker was improved and the temperature of the enclosure after 120 min at steady state increased by $2.8^{\circ}C$ with the increase of the outdoor temperatures from $25^{\circ}C$ to $29^{\circ}C$. In addition, the overall sound pressure level of the developed 400W ferrofluid active speaker showed 111.8 dB and improved 1.9 dB higher than 109.9 dB of the existed speaker.