独立行政法人産業技術総合研究所関西センター講演会
共催：日本音響学会関西支部
日時：2005年7月30日（土），13:30-15:00 （当初予定から変更になりました）
<会場>
〒563-8577 大阪府池田市緑丘1-8-31
独立行政法人産業技術総合研究所 関西センター
産学官研究交流棟（MOL棟） セミナー室
アクセス：http://unit.aist.go.jp/kansai/access.html
阪急宝塚線池田駅より徒歩15分．
市立池田病院の裏（東側），大阪教育大付属池田小学校の
西隣になります．自動車での来所も可能です．
所内建物配置図：http://staff.aist.go.jp/s-nakagawa/aistkansaimap_j.htm
講師：Dr. Peter Cariani
Research Assistant Professor
Department of Physiology,
講師略歴：
-2004.5 Assistant Professor
Department of Otology & Laryngology,
2004.6- Research Assistant Professor
Department of Physiology,
演題：
Temporal
coding of pitch and timbre in early auditory processing: implications for understanding
the nature of central auditory processing
Abstract：
We
will discuss the neural representation of pitch and timbre in the auditory
pathway, from auditory nerve to cortex. We will focus on temporal, interspike
interval codes for pitch and timbre in the auditory nerve and cochlear nucleus
with the aim of shedding light on the elusive and the problematic nature of
their central representations.
Our
working hypothesis is that the auditory system uses information derived from
both neural timing (interspike intervals) and cochlear place (tonotopic maps)
to support perception of periodicity (pitch) and spectrum (timbre). Most
aspects of pitch and timbre perception that are critical for perception of
music and speech appear to be
based
on fine timing information (10-4000 Hz periodicities) that is produced by the
phase-locking of auditory nerve fibers to acoustic stimuli. Like pitch and timbre perception, such
information remains highly precise and invariant over wide dynamic ranges, and
the existence region of this information parallels that of musical tonality
(octave equivalence, musical interval and melody recognition, which holds up to
~4-5 kHz). By comparison, place-based representations are much coarser and
highly level-dependent, not unlike auditory perception in high frequency
registers (above 5 kHz).
At
the level of the auditory nerve the population-wide distribution of interspike
intervals in the auditory nerve forms a general-purpose autocorrelation-like,
temporal representation of the stimulus whose properties explain many diverse
aspects of pitch perception (e.g. missing fundamentals, level-invariance, pitch
equivalence, octave
similarity,
pitch shifts of inharmonic complex tones). We will present data from
neurophysiological and computer simulations studies. Population-interval
distributions (PIDs) also provide robust representations for those aspects of
timbre that are related to
stationary
power spectra (e.g. formant structure and vowel quality). PID-based models
of masking and harmonic resolvability that are
based on the competition of interval patterns integrate this information across
cochlear territories in a manner that reflects
cochlear
excitation patterns. Notions of pitch multiplicity and fusion that are based on
competing interspike interval patterns also provide a basis for tonal
consonance in musical contexts in which pitch (in)stability produces harmonic
tension and relaxation.
A
central question for auditory neurophysiology concerns the means by which the
central auditory system might make use of such timing information, not only to
represent pitch and timbre, but also to form and separate auditory objects
(e.g. different musical instruments, concurrent vowels). An adequate,
neurally-grounded model for the central codes and computations that subserve
pitch should minimally account for 1) equivalence of pure and complex tone
pitches, 2) level and location invariance, 3) the relative nature of pitch
perception, 4) the precision of pitch discrimination, and 5) the ability to
hear out multiple pitches (e.g. in a chord). We will critically discuss several broad
possibilities: pitch detectors, modulation detectors, other time-place
transformations, time-latency transformations, and recurrent timing networks.
<連絡先>
〒563-8577 大阪府池田市緑丘1-8-31
独立行政法人産業技術総合研究所
関西センター
人間福祉医工学研究部門
くらし情報工学グループ
中川 誠司 (072-751-8785, s-nakagawa
aist.go.jp)
添田 喜治
(072-751-9496, y.soetaaist.go.jp)