ACT CITY HAMAMATSU
HAMAMATSU, JAPANACOUSTICAL CONSULTANT:ARCHITECT:OWNER:
THEATER CONSULTANT:SOUND & COMMUNICATIONS:ACOUSTICAL DESIGN INSTRUCTION:CONSTRUCTION COST:COMPLETION DATE:YAMAHA Ad. Sys. Dev. Center
NIHON SEKKEI, INC., et al.
Hamamatsu City, et al.
Theatre Workshop
YAMAHA Ad. Sys. Dev. Center
Kiyoteru Ishii
38,000 Million JPY - Entire Facility
1994

The Act City Hamamatsu was opened just in front of amain railway station as a base for the activities of newcommunities in Hamamatsu City. This venue consists oftwo kinds of halls; 2,336-seat main hall and 1,030-seatconcert hall, and other facilities including a conference
center, an exhibition event hall, a musical instrument
museum, a training exchange center, and private
facilities.
Since the halls are located close to the elevatedrailway tracks, they encounter various acousticproblems, especially vibration problems from the trains.
Before and during the construction, we performed thetrain vibration measurements on the site several times,
then various measures were implemented according tothese investigations. In addition, the logical predicting
methods were developed to evaluate train vibration
based on the vibration power concept and to estimate
the effects of continuous underground wall/expansion
joints.
The main hall was designed as a multi-purpose halladjusted to music performances like opera and classicalmusic concerts, and other performances likeconventions, dramas, light music, etc. as well.

1) Acoustically superior opera house: The hall is basedon a rectangular box shape rather than a horse-shoe or
fan shape to get sufficient lateral reflections, andcomposed of three floors with side balconies which cancreate lateral reflections and also minimize the distanceto the stage from any audience seats (less than 34 m) to
get a sufficient direct sound and loudness.
2) Acoustic treatment within the stage: The hall has 4
full-scale stage floors and can change sceneries easily.
3
The volume of the stage is approximately 50,000 m .
Acoustical shutters have been installed between thesestage floors, to control sound insulation and room
acoustics like reflections for singers and liveness in thestage space during opera performances. Also, soundabsorption treatment has been made in order to avoid
excessive reverberation at the low frequencies duringother performances without the stage reflectors such as
rock concerts, speech, etc.
3) Multi-function Active Field Control (AFC): It isdifficult to obtain sufficient loudness and reverberance
for music performances like opera and classical concertsin large multi-purpose halls only by architectural means.
In order to realize the sound field optimum for both
performances, AFC system has been installed. In
addition, the uniformity throughout the entire room canbe realized by AFC system. The live sound field in themain area is extended to the under balcony area and also
sound energy is exchanged between the stage andaudience area using two independent systems.

To meet their requirements, the following three ideas
have been implemented:

CRITICAL DATA
Seating Capacity
VolumeSurface area
Noise Level
Definition (250 Hz-2 kHz ave.)

2,336
320,839 m
27,602 m
NC-20
47 %

Estimated values for RT from measurement values arein the occupied condition.

ACT CITY HAMAMATSU
HAMAMATSU, JAPANIMAGE TITLELONGITUDINAL SECTION

MAIN FLOOR PLAN

Active Feild Control Scheme