According to Airport Council International (ACI) traffic statistics for 2002, Dubai International Airport is the second fastest growing airport in the world. In 2007, it catered to more than 36 million passengers, with approximately 1,000 daily flight events, including takeoffs and landings. In this paper, we report the first assessment of community annoyance caused by civil aircraft noise exposure at nine sites around Dubai International Airport (United Arab Emirates). Our aim is to assess the relationship between aircraft noise levels and annoyance responses in Dubai. To accomplish our goal, we have adapted the WECPNL and Ldn as the aircraft noise indices in Dubai, and the percentage of highly annoyed responses (%HA) has been used to assess the dose–response relationship of aircraft noise. %HA was obtained using social surveys that were carried out at nine sites within close proximity of the airport utilizing the ISO/TS 15666-2003 questionnaire. Subjects ranging between 20 and 65 years in age were randomly selected. Results show that 41% of the respondents said that they are highly annoyed, a percentage considered high but in agreement with similar studies carried out near major airports in other countries.
Three-dimensional (3D) radiated sound field display systems are important toward realizing ultra-realistic communications systems such as 3D television. In this paper, a 3D radiated sound field display system using directional loudspeakers and wave field synthesis is proposed. The proposed system is based on the Fresnel-Kirchhoff diffraction formula, which is the approximate form of the Kirchhoff-Helmholtz integral equation. The proposed system was developed by constructing the surrounding microphone array and radiated loudspeaker array. To evaluate the performance of the developed system, the positions of sound images were estimated. The results indicated that the 3D sound field is accurately controlled outside of the radiated loudspeaker array by sharpening the radiation directivity of the loudspeaker units and that the sound images are not correctly estimated in the developed system because the radiation directivity of loudspeaker units is not sufficiently sharp.
The constrained interpolation profile (CIP) method is proposed in the field of computational fluid dynamics, because this method is less influenced by numerical dispersions and is stable with an arbitrary time step. In this paper, the CIP method is applied to room acoustic problems, in which boundary modeling and spatial/time discretization are specifically examined. First, frequency-independent and frequency-dependent boundary conditions are introduced and validated with an acoustic tube problem. Second, in one-dimensional and three-dimensional closed sound fields, this paper shows that errors in waveforms and reverberation times using the CIP method are smaller than those using the finite difference time domain method even if the steps for time and space are larger. Third, to deal with complicated shapes, the cubic interpolation with volume/area coordinates (CIVA) method using arbitrary triangular elements is introduced; in two-dimensional sound fields, calculation of the CIVA method is stable even if the quality of triangular elements is low.
Voice activity detection (VAD) in noisy environments is a very important preprocessing scheme in speech communication technology, a field which includes speech recognition, speech coding, speech enhancement and captioning video contents. We have developed a VAD method for noisy environments based on the modulation spectrum. In Experiment 1, we investigate the optimal ranges of speech and modulation frequencies for the proposed algorithm by using the simulated data in the CENSREC-1-C corpus. Results show that when we combine an upper limit frequency between 1,000 and 2,000 Hz with a lower limit frequency of less than 300 Hz as speech frequency bands, error rates are lower than with other bands. Furthermore, when we use the frequency components of the modulation spectrum between 3–9, 3–11, 3–14, 3–18, 4–9, 4–11, 4–14, 4–18, 5–7, 5–9, 5–11, or 5–14 Hz, the proposed method performs VAD well. In Experiment 2, we use one of the best parameter settings from Experiment 1 and evaluate the real environment data in the CENSREC-1-C corpus by comparing our method with other conventional methods. Improvements were observed from the VAD results for each SNR condition and noise type.
The tidal current in the Kurushima Strait of the Seto Inland Sea, Japan was successfully measured during July–August 2009 (36 days) among the three acoustic stations (KR4, KR5 and KR6), located on both sides of the strait. The travel time differences for the two sound transmission lines KR4–KR5 and KR4–KR6 are converted into the range-averaged currents along the transmission lines. The hourly mean of the range-averaged currents varied in the range from −31.1 to 53.8 cm/s for the KR4–KR5 and in the range from −45.4 to 48.7 cm/s for the KR4–KR6 with the error bars of 5.0 cm/s and 6.6 cm/s, respectively. The hourly mean along-line currents are further transformed into the geophysical coordinates with the variation range from −99.1 to 91.6 cm/s and the mean current of −6.6 cm/s for the eastward component VE, and that of (−54.2–31.5) cm/s and the mean current of −7.6 cm/s for the northward component VN. The cross-line volume transport varied in the range of (−17.928 to +17.569) × 104 m3/s, resulting in the mean westward transport of 0.727×104 m3/s. This mean transport reaches a significant level over the error bar of 0.474×104 m3/s.
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