Cenesthesia field of vibration is an acoustic sense that we recognize not from a single sensor like the sense of hearing but from the whole part of the vibration, and the frequency band is lower than 80Hz.
As the evaluation of cenesthesia field vibration, 'vibration level (dB)' which is showed in JIS C 1510 'vibration level meter' and the classification such as 'V-10, V-30, V-50, V-70, V-90' in 'Guidelines for the evaluation of habitability to building vibration' by Architectural Institute of Japan are used.
The frequency band for 'vibration level' is 1Hz-80Hz. And the value of vertical vibration is weighted of vertical characteristics and horizontal vibration weighted of horizontal characteristics, and the unit for it is (dB).
In 'Vibration Regulation Law', the vibration level in the vertical direction is treated as the value of evaluation.
The way to analyze differs depending on the time changing pattern of the vibration level, and evaluated by one of 'instantaneous value', 'arithmetic average amount', 'power average amount' or 'hour rate label L10' in Japan.
In the 'the evaluation of habitability to building vibration' the 1/3 Octave band analysis is implemented targeting at
■ I. Man's action/facilities 3-30Hz (vertical),
■ II. Traffic 3-30Hz (vertical) 1-30Hz (horizontal),
■ III. Wind 0.1-5Hz (horizontal)
and we judge it by applying performance evaluation curve.
The point we need to pay attention to when analyzing is to use the max value of vibration acceleration (0-p, cm/s2).
Vibration of structure bone sound area is the vibration that we feel by the auditory sense after the vibration is made and changed into sound, which the frequency band is between 63Hz-8kHz.
In a case that a building is planned to be built next to a railroad, measuring the railroad vibration at ground level of the planned site or in the building before dismantling to estimate the degree of noise caused by railroad vibration, this measurement is called the measurement of "vibration of structure bone sound area".
Analyzing a method is to calculate the maximum value of vibration acceleration level or the mean value of the energy. We estimate the noise of the target room (NC-value or noise level), using the result we gained, considering attenuation/amplification in the building and converting it into sound pressure level with conversion formula of structure-borne sound.
We undertake from the measurements/analysis using a vibration acceleration pick-up, charge amplifier, data recorder and 1/3 octave analyzer, to estimate the room noise.
To comprehend the characteristics of vibration of the building, we measure the 'driving point impedance' or 'transmission impedance'.
"Driving point impedance" is obtained by the measurement which is implemented when we want to confirm the extent of vibration or the resonance frequency at the target point on the structure and we need to set the vibration point and the response point to almost the same point. It can be calculated by adding the vibration with a hammer which has a force detector inside and measuring the vibration velocity near the vibration point.
Also, calculating the vibration power of machineries is possible by measuring the vibration velocity when the machinery is operating and the driving point impedance when the machinery is stopping at the point where the mount-base is grounded on the floor mounting the machinery that produces vibration.
'Transmission impedance' is obtained by the measurement we do when we want to confirm the transmission character of the vibration from a certain vibration point to the position that is distanced from a vibration point and the measurement method is the same to 'driving point impedance' except that the vibration point and the response point are separated.
In a concert hall, establishing sound field that performers on stage feel 'easy to perform' and also the audience feel 'comfortable sound reverberation' is important.
In a theater, meeting room and party room, the importance is for people to be able to 'communicate easily to each other'.
The measurements of the reverberation time, the echo time pattern, the sound pressure level distribution and syllable articulation are ways to understand the degree of sound reverberation and the ease of listening to sound.
And as the way to grasp the acoustic performance while using electric acoustic facilities, the measurement of echo time pattern, sound pressure level distribution, syllable articulation, transmission characteristics, effective stable gain, maximum playback level and residual noise level are carried out.
Our company is able to analyze various acoustic indexes as followings, using our uniquely developed software called 'AEIRM', an impulse response measurement system.
Echo time pattern (ETP), reverberation time (RT), Early decay time (EDT), Clarity (C, C80), Deutrichkeit (D, D50), center time(ts), Support (ST), syllable articulation (STI,RASTI), etc.
Moreover, visualizing the reflected sound using an omni-directional sound source detection system 'Noise Vision', we inspect that there is a notable sound reflecting part or not.
