How ocarinas work
Understanding the basic principles of how ocarinas work, will help you to identify better instruments.
The sound production mechanism of an ocarina consists of the following components:
- Wind way
- Sound hole
- Finger holes
When you blow into the windway, the air that you are blowing travels across the sound hole as a flat sheet, and this sheet can function as a reed. As it does so, the moving air syphons additional air with it, which can either pull air into, or out of the chamber.
- Initially, the air flows out of the chamber, cleating a low pressure in the chamber.
- As it does so, it causes the pressure in the chamber to drop, which pulls the air reed towards the inside of the chamber.
- The pressure in the chamber then raises, pushing the air reed towards the outside again, and the cycle continues.
Finger holes and limited range
The pitch of an ocarina can be raised by opening holes in its surface, as they reduce the resistance to air moving in and out of the chamber, allowing it to move more quickly.
A critical thing to understand with ocarinas is that opening finger holes degrades the efficiency of tone production.
As holes are opened, more and more air is required to compensate for the air which is being lost, and at some point this becomes impossible. Ocarinas have a limited range because of this. The ocarina is inherently a 'lossy' instrument.
The exact range which can be attained from a single chamber does depend on how the instrument is designed. However, the best sound possible does tend to come from minimising the total range.
Other factors affect range, the most important being the voicing neck and windway bias, covered below.
The voicing neck
In ocarinas, the sound hole is generally not positioned directly in the chamber, but set back into the mouthpiece, inside a constrained volume that I call the 'voicing neck'. This area traps a 'plug' of air which slows down the oscilations of the chamber, allowing the same pitch to be attained with a smaller chamber. This improves the tone quality of the instrument's high notes.
The need for a neck depends on the pitch of the ocarina. Soprano ocarinas do not need a spasific 'neck' as the narrow diamiter of the chamber creates resistance in itself. Howeaver, as an ocarina gets larger and lower pitched, more neck is required to prevent the chamber volume expanding uncontrollably, resulting in an excessively large instrument with very poor high notes.
Voicing necks are most often created by positing the voicing further back in the mouthpiece. Howeaver, note that the effect of a voicing neck can be created in other ways, for example using internal walls around the voicing in an otherwise open chamber.
The presance of a voicing neck does indicate quality, and a more experienced maker. A bass ocarina with no neck, would indicate that the maker was not aware of this principle, and such an instrument will be excessively large and have poor high notes.
Another aspect of ocarina design you should be aware of is windway bias, the relitive angle between the windway and the labium. The windway can be angled such that it is eather directing the air primerily into the chamber, primerily outside the chamber, or equally to both. Which I call 'internal bias', 'external bias' and 'neutral bias'.
In my experiance, external bias produces the best sound, and logically this makes sense as the air is being directed away from the chamber, where it can move freely away from the body of the instrument and thus avoid making noise. If the air is biased into the chamber, it must leave via the finger holes, which is a far more convoluted path.
Bias angle can arrise without a maker's awareness, if they make the body of an instrument without awareness of how this affects tone, and just design the voicing around the angle that the windway 'works best' within the physical form they have. From my own experiance doing this when I first started making, such a design process tends to result in internal bias, combined with a steep external ramp.
My current experiance says that steep ramps are bad design, as they force the air to make a large change in direction to leave the chamber, which seems to create a lot of terbulance and risistance.
[Need pictures showing ramp, and ramp elimination]
Having a 'ramp' on the inside of the chamber does not seem to matter that much. Probably due to what I noted above about external bias leaving the air a clear path to move away from the body.
Range and pitch
The attainable range in an ocarina tends to reduce the larger it is.
Larger sound holes are less efficient, as the further air must travel, the more terbulant it becomes.
Attaining the same fingering system and range regardless of instrument size makes no sense.
Focusing on range compromises other aspects of instrument design.
Understanding these things will help you to chose better instruments.
Awareness, a maker may be designing an instrument for visuals, which ends up disregarding acoustic requirements, resulting in a worse instrument. The need for geomitary dictates how the external form must be.
The ocarina being a lossy instrument is not a bad thing, howeaver it does create some guidance. for example to create a larger range, it is more productive to add more chambers than add more holes, as more chambers each having fewer holes works within the instrument's limitations.
Ocarina range does not scale liniarly, and larger, lower pitch instruments are less able to create a large range.
Focus may not be on creating the most playable instrument which is ok, but awareness of this is important.