AES Tokyo Convention 2009
Poster Session P1

Preference of spatial impression shall be different individually, and it is also hard to explain her/his preference by herself/himself. In this paper, we aim at revealing which auditory impressions dominate a subject's preference in the different venues: an auditorium and a concert hall. In the framework of multiple regression analysis, preference as a response variable can be explained by the linear combination of some auditory impressions as explanatory variables, where both preference and auditory impression are obtained by listening tests for chorus music.

In a sound system for large venues such as drama theaters, extending source imagery might enhance the intention of the sound designer integrating with other various controls on spatial impression. With the existing knowledge on the physical characters associated with perceived width, we created an algorithm extending source imagery horizontally in the multichannel reproduction system. The proposed method controls the degree of variation in perceived auditory image width by adding two extra sound sources with the extended angles from the main source. With the optimized angles and gains of the extra sources, the subjective evaluation showed that the proposal method intuitively and effectively extends the perceived width in the context of the multichannel sound system for a large venue.

Previously we reported spatial image improvements of Piano sound reproduction using multiple loudspeakers. In this second report, we describe the improvement in the quality of piano sound reproductions attained by increasing the number of multichannel loudspeakers, especially noticeable at higher sound pitches.

When an electronic instrument is reproduced in a space, its sound quality is often dependent on the character of the loudspeaker. In particular, for a composition with multiple tonal variation, the reproduction sound system should represent not only tonal, but also spatial identity, from which listeners can perceive fidelity of the sound field. This paper is the result of a series of investigations into an ideal reproduction system for an ensemble of electronic instruments, which gives listeners more natural and realistic impression that an equivalent acoustical instrument would generate. As the first step, the sound fields associated with six conventional loudspeakers were subjectively compared. The analysis of the subjective response showed that the reproduced sound fields of the electronic ensemble could be located in a two-dimensional perceptual space, which indicates the semantic relationship between attributes and the stimuli. The subsequent multiple regression results showed that the total impression of music was accounted for by two attributes: Distance and Brightness.

In this report, we will describe experiments using headphones to evaluate the sensitivity to the horizontal location of the sound sources. We will also report on the effects of room reflection as well as the effects of degradation of sound quality when using audio encoding. Unexpectedly, the sensitivity did not consistently decrease when the room reflection increased; or when lower bitrates were used.

This paper proposes a sound quality customization method based on an Paired Comparison interactive genetic algorithm (PC-IGA). A user who is not familiar with music and/or audio devices finds it difficult to customize the reproduction parameters to suit his/her preferences. Our solution is a system that customizes the reproduction parameters for headphone use by an intuitive user input panel; the IGA analyzes the user's inputs and generates the appropriate parameters. The system makes it easy, even for novices, to obtain the preferred sound quality. In this paper, the proposed system simplifies the evaluation by using pair comparison. Results of a subjective assessment experiment, demonstrate that the preferred sound quality can be obtained through this system.

Considering the ideal music practice room, are there any tendency beyond the personal preference regarding the size and the shape of the room, the material of the walls, and the reverberation sound? To study about these, author had a questionnaire to ask the requests for music practice rooms to the students who use them usually. From the result of the questionnaire, it became clear that many answerers require `appropriate reverberation' despite differences of music instruments or years of experience. The author tried to survey `appropriate reverberation' and size of the practice room and had experiments focused on relationship between direct sound and early reflections of room. The aim of the experiment was to study relationship between direct sound and single early reflection in a music practice room. As a result, there is no significant deference between each musical instrument, but there is a tendency by grouping the musical instrument. To confirm this result, the rooms were simulated which applied the preferred delay time into actual room size considering mean free path. Two types of room were simulated, one has all reflections and the other has single reflection. From the interview of the player who compares the simulated sound of these rooms, they preferred the room which has all reflections. It is assumed that the following reflections are important for natural impression.

The sound field in enclosed space of rectangular shape can be effectively described by modal model. In this model, physically reasonable damping term of each mode must be taken into account. This report introduces the outline of derivation process of modal summation formula and several practical methods for introducing damping term. The good agreement of the results obtained in numerical simulations and the experiments indicate the validity of the proposed method.

Acoustical properties and physical conditions of mixing environments in Japanese video-game sound production studios are described. To research the interchangeabilities and the differences in the mixing environments among Japanese game production studios, acoustical measurements and field surveys of the monitoring conditions were carried out at different mixing studios. We analyzed the measurements and surveys to give the following values for each studio to show the existing conditions and examine the interchangeabilities among mixing environments in Japanese game productions; 1) monitoring responses, 2) reverberation times, 3) averaged absorption coefficients of rooms, 4) playback levels, 5) reference levels of the monitoring chains, 6) physical dimensions of rooms.