Personal sound system design for mobile phone, monitor, and television set

263 Pages·2017·1.86 MB·English

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THURSDAY MORNING, 3 JULY 2008 ROOM 242B, 8:00 A.M. TO 12:00 NOON
Session 4aAAa
Architectural Acoustics: Architectural Acoustics Potpourri
David T. Bradley, Cochair
124 Raymond Avenue, Poughkeepsie, NY, 12604
Andrea Farnetani, Cochair
Engineering Dept. - Univ. of Ferrara, Via Saragat, 1, Ferrara, 44100, Italy
Contributed Papers
8:00 8:40
4aAAa1. Irregular sound absorbers work better. Bernard 4aAAa3. The vibration sound absorption theory of soft materials. Xin
Sapoval 共Ecole Polytechnique, PMC-Polytechnique Route de Saclay, An Zhang 共Xi’an Polytechnic University, 134#, Key Laboratary, 19 South
91128 Palaiseau, France,
TM TM
room geometry influences reverberation time both at macro and micro lev- In order to create an optimum Room Acoustic Comfort 共RAC 兲 in
els, and this influence cannot be separated. To validate these conclusions in rooms it is important to consider a variety of different acoustic descriptors.
a real sound field, additional measurements have been conducted in spe- These descriptors must match and facilitate for wanted human qualities such
cially prepared physical models of rooms. In several models of different as ability to concentrate, reduced stress, clear speech etc. In this process it is
shapes selected from previous results, scaled 1:10, the changes of scattering important to consider the people, what they do 共the activity兲 and what room
were introduced by appropriate modifications of interior surfaces. The re- they will be in. Today, when designing ordinary rooms from an acoustic per-
sults have confirmed the previous study conclusions. spective, mainly reverberation time 共T20兲 is utilised - both in practice but
also in building regulation and standards. Reverberation time 共T20兲 only de-
scribe the later part of the decay curve, and therefore only partly mirror the
9:40
wanted acoustic reality. Thus, based upon a large number of acoustic mea-
4aAAa6. Room acoustics prediction based on multiple linear
surements, we suggest a ⬙cocktail⬙ of acoustic descriptors for ordinary
regressions and artificial neural networks. Maria Ribeiro 共FEUP”DEC,
rooms in buildings like schools, offices, health care premises etc. These de-
Rua Dr. Roberto Frias, 4200-465 Porto, Portugal,
11:40 system. Furthermore, the IR is known to behave stochastically when the
4aAAa11. Measuring the mixing time in auditoria. Guillaume sound field becomes diffuse, that is, after a certain time called mixing time.
Defrance 共Institut Jean le Rond d’Alembert, Laboratoire d’Acoustique Mu- This study aims at characterizing the IR mixing time. Three methods are
sicale, 11, rue de Lourmel, 75015 Paris, France, presented for visualizing and detecting the time evolution of the IR
Contributed Papers
8:40 adjoins a reverberation room via a transmission plug where canopy panel
4aAAb3. Numerical study of sound transmission loss using an indirect sections are mounted for testing. Boundary element methods in LMS Virtual
boundary element method. Matthew Cassidy 共Queen’s University Bel- .Lab are used in conjunction with a baffle model to simulate the test facili-
fast, School of Mechanical and Aerospace Engineering, Ashby Building,
ties for transmission loss. On one side of this wall the reverberation room is
Stranmillis Road, BT9 5AH Belfast, UK,
which will also avoid the need for the knowledge of the exact microphone Predicting the sound pressure level at a workplace requires in-situ char-
location by continuously moving the sample under test. Different results will acterization of the facings. This work describes a new method for the mea-
be presented and compared to the traditional techniques. surement of the sound absorption coefficient of flat panels present in indus-
trial halls. In such room, it is necessary to separate the echo coming from the
10:20 studied panel from the others due to the entire reverberation. This separation
4aAAc2. New method for measuring sound absorption coefficients in has been achieved in space by an acoustic array and in time by an impulse
sound source. The array processing uses a multipolar weighting to achieve a
an industrial hall. Joël Ducourneau 共Faculté de Pharmacie de Nancy,
directivity constant with frequency and with attenuated side lobes. This
Université Henri Poincaré, 5, rue Albert Lebrun, BP 80403, 54001 Nancy,
weighting requires a limited number of microphones. The impulse source
France,
surements and spreading out the spectral sound energy in time. As a result The transfer of structure borne sound power depends on the mobility of
an efficient use of available sound power is possible. In a laboratory is in-
the source and the receiver. If source and receiver are coupled through mul-
vestigated how to use mls or sweep signals as a source signal and deconvo-
tiple points, the interaction between those points has to be accounted for.
lution as a measurement technique to obtain the sound insulation under
The force of a washing machine injected into a lightweight wooden floor is
noisy conditions.
analysed to develop a simple measurement procedure for similar multiple
12:00
point structure borne sound sources. A complete mobility model will be
4aAAc7. Characterising a washing machine as a structure borne sound
compared with a simplified model based on a reduced mobility matrix. The
source on a lightweight floor. Matthias Lievens 共Institute of Technical
Acoustics, Neustraße 50, 52056 Aachen, Germany,
the decay curves measured at 72 fixed positions suggests that spatial distribution of steady state sound pressure level, rotation speed of
microphone, and reverberation time of test chamber are key factors of errors. As a conclusion, the strict guideline for measurement of
reverberation time with microphone rotator should be presented to minimize errors.
2:20
4aAAc11. Uncertainty in building acoustics. Werner Scholl 共Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116
Braunschweig, Germany,
given in the relevant parts of the ISO 140 series. The accuracy of acoustic ating condition of the equipment 共repeatable settings兲 and the reproducibil-
measurement methods in buildings depends on many factors. In this round ity, using different types of acoustic instrumentation and varying the method
robin test, the situation 共varying from straightforward rectangular rooms to 共choice of source and microphone positions兲. In particular the tolerance lim-
half open spaces with all kind of shapes兲 and the construction details were its in the verification of the requirements of tender specifications were
kept fix. The analysis was aimed at investigating the influence of the oper- investigated.
3:40-5:00 Posters
Lecture sessions will recess for presentation of poster papers on various topics in acoustics. See poster sessions for topics and abstracts.
Invited Papers
5:00
4aAAc15. Handling of uncertainties for CE marking concerning Sound Transmission Loss of glazings. Marc Rehfeld 共Saint
Gobain Glass, CRDC, B.P. 40103, 60777 Thourotte Cedex, France,
6:20 6:40
4aAAc19. Previous results on the evaluation of the influence of sound 4aAAc20. Uncertainty analysis in acoustical modeling of room.
level meter case in diffuse field. Alfonso R. Molares 共University of Dominik Mleczko 共Romera 17, 33-300 Nowy Sacz, Poland,