This paper presents how to design and simulate two different topologies of a bandpass (BP) rectangular waveguide filter using a direct coupled resonator technique operating at 12 GHz. The filters are characterized by a cross coupling (CM) which produces a single attenuation pole at finite frequency used to realize the bandpass response. The filter resonators provide3rd and 4th order designs with a pseudoelliptic response using High Frequency Structure Simulator (HFSS) simulator. Transmission zeros are obtained through coupling between the fundamental mode and high mode. The filter structures are validated leading to obtain transmission zeros close to the bandpass. The simulated waveguide filters with a central frequency exhibit an insertion loss of 0.4/0.3dB and a return loss of 20/23dB for the whole bandwidth ranging from 11.85GHz to 12.15GHz that show good electromagnetic responses for the simulated rectangular waveguide filters.

This paper presents the results of measurements of the sound absorption coefficient of auditorium seats carried out in the laboratory using two methods. In the first one, small blocks of seats in various arrangements were studied in a reverberation chamber to determine the absorption coefficient of an auditorium of infinite dimensions. The results were compared to the values of the absorption coefficient measured using the second method, which involved samples enclosed within a frame screening the side surfaces of other auditorium blocks. The results of both methods allowed for the assessment of the sound absorption coefficient of an auditorium of any dimensions while taking into account the sound absorption by the side surfaces. The method developed by the authors will simplify the currently known measurement procedures.

Chinese is a tonal language, which differentiates it from non-tonal languages in the Western countries. A Chinese character consists of an initial, a final, and a tone. In the present study, the effects of noise and reverberation on the Chinese syllable, initial, final, and tone identification in rooms were investigated by using simulated binaural impulse responses through auralization method. The results show that the syllable identification score is the lowest, the tone identification score is the highest, and the initial identification scores are lower than those of the final identification under the same reverberation time and signal-to-noise ratio condition. The Chinese syllable, initial, and final identification scores increase with the increase of signal-to-noise ratio and decrease of the reverberation time. The noise and reverberation have insignificant effects on the Chinese tone identification scores under most room acoustical environments. The statistical relationship between the Chinese syllable articulation and phoneme articulation had been experimentally proved under different noise and reverberation conditions in simulated rooms.