5254 Topics : Propagation delay

[ 10/15/2018 ]     Labels:  49a.Endpin.Effects

 
Let's check up the delay time(milliseconds) between bridge, top-plate(sound), tailpiece and endpin when a mezzo-forte pizzicato is plucked on A(221Hz), D(147Hz) or C(66Hz).
Typical data are shown as H2ms to H5ms charts.
The results should be kept in mind at the detail researches hereafter.
Generally, the delays are expected as;

Bridge --> Tailpiece = 0ms to 1ms,
Bridge --> Top plate = 0ms to 2ms,  (sound speed delay 340mm/ms is already considered)
Bridge --> Endpin    = 1ms to 2ms

メゾフォルテ・ピツィカートで、表板(発生音波)・駒・テールピース・エンドピン間の振動の伝播(遅れ)をチェックしておこう。
これは今後の観察(ひとつづつの振動の相互影響調査)のために必要である。
H=2ms～5msで測定した、A(221Hz)、D147Hz)、C(66Hz)の代表データを示す。結論として、
駒→テールピース の振動伝播遅れ = 0～1 ms、
駒→表板 の振動伝播遅れ = 0～2 ms、(音速340mm/ms考慮済)
駒→エンドピン の振動伝播遅れ = 1～2 ms と考えてよさそうだ。

5244. Extensive Measurement Images

[ 09/03/2018 ]     Labels:  49a.Endpin.Effects

 
How is a cello resonating when a pure pizzicato is plucked or when played forte by arco?
How is a tailpiece(or bridge) sharing the mechanical resonance?
Can whole span waveform chart give us any hint to the "response"?
Further measurements will be taken place and some topics will probably be posted soon.

5242. Test measurement-2 [Propagation]

[ 08/28/2018 ]     Labels:  49a.Endpin.Effects

 
Vibrations from A(221Hz, mezzo-forte pizzicato) note are traced on the screen of oscilloscope. The width of each lattice is adjusted as 2 milliseconds.
Vibrations(mechanical resonance) seems to propagate from Bridge -> Tailpiece -> Endpin.. accompanying 1 to 2 ms delay.
At last, the vibration is almost stopped at the tip of endpin, because an endpin can hardly shake the floor.

A(221Hz,mf)ピチカートの振動の伝播を追ってみる。オシロスコープの水平方向の格子幅は 2ms。
振動は、駒→テールピース→エンドピン (→床)の順で伝わっているように見える。時間差は 各々1ms～2ms。
しかし床へは大きな振動は伝わっていない(床を物理的に振動させることができていない)ように見える。

5241. Test measurement-1 [Sound speed]

[ 08/23/2018 ]     Labels:  49a.Endpin.Effects

 
Sound can travel in air at approximately 340 meters per second.  i.e. 340 millimeters per millisecond.
Let's check it up by mezzo-piano pizzicato!
Actually, top-plate of cello needs to be moved and compress the air, it might be needed 2 to 3 milliseconds.
In this measurement, 3 microphones were not the same model.
However, oscilloscope shows somehow the most likely delays.

5240. New staffs

[ 08/21/2018 ]     Labels:  49a.Endpin.Effects

 
Let me introduce my new staffs. Measured data are finally integrated to new oscilloscope(RIGOL DS1054Z) that has 4 analog input channels. 
They will make a good job.