Hiroko Terasawa

The thirteen colors of timbre

We describe a perceptual space for timbre, define an objective metric that takes into account perceptual orthogonality and measure the quality of timbre interpolation. We discuss three timbre representations and measure perceptual judgments. We determine that a timbre space based on mel-frequency cepstral coefficients (MFCC) is a good model for a perceptual timbre space.

Voisticky: Sharable and portable auditory balloon with voice sticky posted and browsed by user;s head direction

In this paper, we introduce an effective scheme for browsing and sharing personal voice memos using three-dimensional (3D) auditory space. We proposed an intuitive framework to record and browse numerous personal voice memos using the users head directions to post voice memos in user-relative auditory directions for each utterance. The user can define the sharing attribute of each voice memo in the edit mode so that personal and public voice memos are appropriately shared with the permitted users. The shared spaces, which are hemispherical auditory balloons, are overlapped or arranged in separated angles by the number of sharing users. The results of user tests showed that the user could intuitively recognize the existence of whole memos and that there is a possibility of different feelings and cognitions in the voice memos using our proposed scheme compared to conventional voice memos.

Wearable Auditory Biofeedback Device for Blind and Sighted Individuals

This study discusses the feasibility of a reference-tracking task of ankle-joint exercise with interactive sonification for sighted and blind individuals in terms of both objective and subjective evaluations via our wearable auditory biofeedback device using the instrumented ankle-foot orthosis (AFO) called GaitEcho. Our experimental results suggest it offers similarly adequate functionality for both blind and sighted participants.

A hybrid model of timbre perception.

Timbre is a fundamental attribute of sound. It is important in differentiating between musical sounds, speech utterances, and characterizing everyday sounds in our environment as well as novel synthetic sounds. A hybrid model of timbre perception, which integrates the concepts of color and texture of sound, is proposed. The color of sound is described in terms of an instantaneous (or ideally timeless) spectral envelope, while the texture of a sound describes the temporal structure of the sound, as the sequential changes of color with an arbitrary range of time‐scale. The computational implementation of this model represents a sound’s color as the spectral envelope of a specific window, and its texture as the granularity (or microtexture) of the corresponding window. The temporal structures across windows from both color and texture parts of the model serve as the texture of a sound in a larger time‐scale. In support of the proposed theory a series of psychoacoutic experiments was performed. The quantitative relationship between the spectral envelope and subjective perception of complex tones used Mel‐frequency cepstral coefficients as a representation. A perceptually tested quantitative representation of texture was established using normalized echo density.

Comparative Effects of Auditory Electromyographic Biofeedback for Participants Who Are Blind and Sighted

This study examined differences in auditory electromyographic biofeedback (AEB) effects between participants who were sighted and blind. Past research makes clear that AEB is effective for people who are blind, particularly because of their reported superiority in auditory processing, but no study has directly compared AEB efficacy between participants who are sighted and blind. A total of 11 participants who were sighted and 10 who were blind performed a motor task requiring 20 nonfatiguing muscle contractions at 20% maximal voluntary contraction (MVC) with or without AEB. AEB reduced the error (calculated as the absolute difference of two consecutive contractions) among both participant groups, and the error for the group without biofeedback was greater for the participants who were blind than that for the sighted participants (5.20% ± 2.05% MVC and 3.30% ± 1.26% MVC, respectively; p < .05). This finding was consistent with subjective rating data, also indicating a trend toward greater difficulty for participants who were blind when performing without biofeedback. Moreover, the AEB/no biofeedback condition showed fewer errors for the participants who were blind than for the participants who were sighted during the last part of the task (p = .036), indicating that participants who were blind were better at maintaining the AEB effect. These data suggest that the poor motor performance of participants who were blind was greatly improved with AEB, suggesting important applications of AEB for assistive technologies, adapted sports, and activities of daily living.

Acoustical measurement of modern Japanese libraries

The function of modern libraries is transforming from a quiet reading space to an active, social, and interactive learning place for old and young people including children. We investigate the room acoustics of modern libraries in order to examine if they can accommodate both needs of silence and bustling communication. We measured impulse responses and sound-decay distribution patterns at three libraries (two university libraries and a public library) with different architectural styles. In addition, we measured the noise level during the library opening hours with active visitors. Every library showed different patterns of sound propagation and visitor activities. Library spaces with densely installed shelves highly absorb noises, while spaces with few shelves and a multiple-height structure were highly echoic. Some carefully designed spaces showed a clear acoustical zoning, that the sound from bustling noise area hardly reach to the quiet reading area even with a high ceiling and sparse shelves.

The sound of smile: Auditory biofeedback of facial EMG activity

Abstract In this paper, a real-time interactive system for smile detection and sonification using surface Electromyography (sEMG) signals is proposed. When a user smiles, a sound is played. The surface EMG signal is mapped to pitch using a conventional scale. The timbre of the sound is a synthetic sound that mimics bubbles. In a user testing of smiling tasks, 14 participants underwent the system and are required to produce smiles under three conditions, i.e., auditory feedback with sonification, visual feedback with mirror, and no feedback. The impression of the system is evaluated through questionnaires and interviews with the participants. In addition, we analyzed the total amount of muscular activity and temporal envelope patterns of the sEMG during smiling. The questionnaire and interview showed that users felt that (1) the sonification system well reflects their facial expressions, and (2) the sonification system was enjoyable. The users also expressed that the auditory feedback condition is easier to smile with, as compared to the visual feedback or no feedback conditions. However, the analysis of sEMG did not provide a quantitative difference among the three conditions, which is most likely due to the experiment design, which lacks socially engaging settings.

Discrimination and identification of environmental sounds among people with hearing impairment

We report that people with hearing impairment (HI) can better discriminate environmental sounds than identifying the same sounds. In order to investigate the perception/recognition of environmental sounds by people with HI, researchers often choose identification task as a measurement tool. However, since identification ability is developed upon discrimination ability, the discrimination ability should be studied too. We used 9 environmental sounds as stimuli for both discrimination and identification tasks, and 16 participants with HI joined the experiment. In the discrimination task, the participants listened to the paired short stimuli, and reported the perceived difference. In the identification task, the participants listened to each stimulus and reported the name of the sound source. The order of discrimination and identification tasks is counterbalanced among the participants, and we also tested 10 people with normal hearing for comparison. The results showed a clear contrast between the discrimina...

Analysis of the relationship between muscle activity and acoustic features during trumpet play and the construction of a myoelectric visual feedback system

Breath control and lip vibration are crucial for a stable performance while playing the trumpet. We analyzed the differences in abdominal and orofacial muscle activity in acoustic features such as pitch (B♭2, F3, B♭3, F4, B♭4), intensity (pp, mf, ff), and duration (0.75, 6 s) during the preparation and sustain periods using surface electromyography in 11 amateur trumpeters. When the pitch was high, the activity of both muscles increased in both the preparation and sustain periods. However, when the intensity was high, the activity of both muscles increased only during the sustain period. Orofacial muscle activity was lower after tone production and abdominal muscle activity was higher after tone production than before tone production. In addition, we developed a visual feedback system that displays the muscle activities and acoustic features related to the produced sound as biofeedback can make learning performing technique efficient (LeVine, 1984). This system enables the player to objectively recognize ...

An Instrumented Ankle-Foot Orthosis with Auditory Biofeedback for Blind and Sighted Individuals

GaitEcho, a wearable auditory biofeedback device using an instrumented ankle-foot orthosis for gait rehabilitation, was developed. Its feasibility for rehabilitating sighted and blind individuals was investigated employing a reference-tracking task for an ankle-joint exercise. Experimental results suggested that GaitEcho offers similarly adequate functionality (i.e., angle controllability, timing controllability, and task difficulty) for both blind and sighted participants in conducting ankle-joint exercises. Furthermore, blind participants reported higher understandability and enjoyment than sighted participants, suggesting positive emotional effect of auditory biofeedback for blind users.