September 30, 2020 at 2:15 pm #311freixasKeymaster
This is mostly a placeholder topic. If anyone wants to tackle it, feel free.
A reed does not produce sound the instant that air flows over it and through the reed plate opening. It takes a minimum amount of air to begin the reed vibration.
Some things I’d be interested in knowing:
- What is the minimum airflow needed for a reed to sound?
- How long does it take for the reed to sound once this minimum air flow is provided?
- How does the sounding time vary by airflow? In other words, if more than the minimum airflow is provided, does the reed sound sooner? Later? With the same delay?
- What is the physics behind all the above?
These questions might be difficult to answer. First, one needs a consistent, controllable airflow source. Then one needs to measure a very short amount of time—the time from when the airflow begins until the sound begins.
One possible air source might be a small fan (perhaps a computer fan) with variable speed control. The air could be captured with a funnel and directed to a tube and into the melodica. The fan-speed-to-air-speed would need to be calibrated. One would need to subtract latencies from other parts of the system (the time needed for the air to reach the reed and then the time needed for the sound from the reed to reach any timing device).
Do you begin measuring latency by powering up the air source and beginning the timing when a key press begins? When the key press ends? Or do you press the key and begin timing when the air flow begins. All these choices add latencies which aren’t from the reed.
The answers I expect:
- The latency is low.
- The latency is longer when sounding a reed at low volume than at high volume.
- The latency varies by reed.
- Lower reeds may take longer to sound, in general. Or high reeds.
I also expect inconsistencies. For example, pick any three notes on the keyboard and press them without blowing. Start blowing as gently as possible and continue slightly harder until a reed begins sounding. The reed that sounds first will not always be the lowest reed or the highest reed. You may have to try several different combinations as it will differ from keyboard to keyboard. I suspect that very small differences in the size, shape, and composition of the reed will influence the latency.
Because Western free reeds are present in other instruments which have been studied, it might be possible to find existing studies which should apply to the melodica.
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