In order to clarify the features of environmental sounds, psychoacoustical experiments using onomatopoeic representations were conducted. The onomatopoeic representations obtained for each sound and participant were expressed using phonetic parameters, such as place, manner of articulation, and vowels. Onomatopoeic representations were classified based on similarities of phonetic parameters using a hierarchical cluster analysis. As a result, similar acoustic properties were identified in the stimuli expressed by onomatopoeic representations classified into the same clusters. Furthermore, the auditory impressions associated with stimuli were measured by a semantic differential method using 13 adjective pairs. Factor analysis was applied to the average ratings for each sound for each scale. The three factors obtained were the emotion factor, the clearness factor, and the powerfulness factor. From these results, the relationships among the acoustic properties of sound stimuli, the impressions associated with them, and their onomatopoeic features were discussed. For example, onomatopoeic representations including voiced consonants were frequently used for sounds displaying components in the frequency region below about 1 kHz in their spectrum, inducing “powerfulness” and “darkness, dullness, and muddiness” impressions. Furthermore, similar relationships were found in supplementary experiments using various band noises.
When the towing vessel was turned, the Directions-of-Arrival (DOA) estimation would be critically degraded if the horizontal towed linear array shape was still assumed to be a straight line. Especially to the coherent signals, which were frequently encountered in shallow water environment due to the multipath propagation, the DOAs could only be estimated by applying the Maximum Likelihood (ML) estimator with a priori information of the array geometry. In this paper, an effective method was proposed to simultaneously estimate the DOAs and the sensor positions of a bended towed array during a turn in the coherent signal environment, which was called the array shape self-calibration problem. Firstly, the spatial signature corresponding to the arbitrary number of incident coherent signals was blindly obtained from the output of the Constant Modulus (CM) array only based on the array sample data. Then the towed array shape calibration problem could be described as a nonlinear optimization problem and solved by Genetic Algorithm (GA). Once the towed array shape has been calibrated, the DOAs of coherent signals would be estimated subsequently by using the ML estimator. Finally, numerical examples were conducted to illustrate the effectiveness of the proposed method.
We propose a method for predicting the absorption characteristics of a fibrous material, that is glass wool, covered with a perforated facing and an impermeable film, typically used for noise barriers. The method is based on Ingard and Bolt’s model. It accounts for interactions among perforated facing, film and fibrous materials. The interaction occurs in areas where they are close to each other. That area was determined empirically as the coverage. The coverage is approximately 10 mm for a perforated facing with a 0.2 open area ratio. In the coverage, the perforated facing increases the acoustic impedance of film and fibrous material according to distance. The fibrous material causes acoustic resistance to the film when the film contacts the fibrous material. The formulae for their acoustic impedances were derived from many results of acoustic impedance measured using an impedance tube. The end correction of holes of the perforated facing was modified using the relationship between the measured values of resonance frequency for Helmholtz resonators with the perforated plate and their open area ratio. Results predicted by this method agree well with measured results obtained in most instances.
This paper investigates the contribution of pitch-accent information to Japanese spoken-word recognition. Pitch accent of spoken words was manipulated by controlling F0. First, the present author investigated the relation between word intelligibility in the presence of noise and the adequacy of accent type in those words. In the intelligibility test, participants were presented with speech stimuli and a pink noise together, and were required to identify the word. In the rating test, the same participants were presented with the same speech stimuli and were required to rate the adequacy of the words’ accent types. Results indicated that the spoken words with more adequate accent type were more intelligible in the presence of noise. Next, the present author investigated the relation between reaction time in shadowing words and the adequacy of accent type in those words. In the shadowing task, the participants were required to shadow a word whose accent type was manipulated as soon as they identified it. The same participants participated in the rating test. The reaction time in the case of the words with an adequate accent was shorter than in the case of an inadequate one. These results support the hypothesis that pitch-accent information in Japanese spoken words might facilitate word recognition.