How ocarinas work

Understanding the basic principles of how ocarinas work is very useful for anyone who wants to play the instrument seriously. As of writing most people buy ocarinas online, and it is rarely possible to try one before you buy it.

A bit of experience in the workings of the instrument lets you estimate how an ocarina will play without ever playing it, allowing you to identify ocarinas that better fit what you want to use them for, and play on them.

How ocarinas produce sound

The sound production mechanism of an ocarina consists of the following components:

• Wind way
• Sound hole
• Labium
• Chamber
• Finger holes

Ocarinas are played by blowing into the windway, and when you do so, the windway focuses the air into a flat sheet that travels across the sound hole. Such an arrangement is called an 'air reed', as the airflow serves the same function as a reed in an instrument like a clarinet or harmonica.

The air flowing over the sound hole is split by the labium, and depending on the pressure within the chamber, the air will either flow towards the outside, or inside of the chamber:

• If the pressure within the chamber is high, the air-reed bends towards the outside, pulling air out of the chamber and leaving it at a lower pressure.
• If the pressure within the chamber is low, the air-reed bends to direct air into the chamber, leaving it at a higher pressure.

This happens continually, producing sound waves that we can then hear. For example if an ocarina was producing a note matching the international concert pitch, it would be vibrating 440 times per second. Note that only the air is vibrating, and the material of the instrument is just acting as a container. The material has very little impact on the sound.

The exact pitch produced varies depending on quite a lot of factors:

• How hard the instrument is blown, the pitch raises as it is blown harder.
• The volume of the chamber, larger chamber volume results in a lower pitch.
• Ambient air temperature, the higher the temperature, the higher the pitch.

Finger holes and limited range

In addition to blowing pressure, the pitch of an ocarina can be changed by opening holes in its surface. The pitch raises as the total area of open holes increases as the air can move in and out of the chamber more easily.

Unlike tubular instruments the exact locations of the finger holes on an ocarina does not matter that much. The entire chamber is always oscillating and the holes are placed to be ergonomic for the player.

Rather, the pitch is determined by a combination of the total area of open finger holes, as well as how hard the player is blowing. Ocarinas are designed with a fingering system where the area of the holes increases progressively, to produce the correct notes.

It is important to note that ocarinas function due to pressure difference between the air inside and outside the chamber. Opening holes is actually a problem as it allows the air to escape, and you have to blow harder and harder to maintain pressure in the chamber.

Past a certain point it is no longer possible to compensate for the air being lost. The sound becomes more airy, and eventually the instrument stops sounding entirely.

Ocarinas have a limited range because of this. The exact range which can be attained from a single chamber is slightly more than an octave. It does depend on other factors mentioned later, but there is always a trade off between range and sound quality.

Sounding range and chamber volume

The range that an ocarina is capable of producing varies depending on the total chamber volume. Ocarinas with a smaller chamber volume tend to be able to sound a larger range:

• High pitched ocarinas can easily produce a range of 21 chromatic notes (12 finger holes), without the high notes being notably airy.
• Low pitched ocarinas produce a range of about 18 chromatic notes (10 finger holes), and can still sound more airy on the high notes.

Exactly why this happens I am not completely sure, it seems to be a combination of factors:

• Smaller chambers contain a much lower mass of air, and require less energy to drive.
• Long-thin chambers seem to be more efficient, and making a chamber with this form is easier when the internal volume is smaller.
• Smaller chambers use smaller sound holes, the air has less distance to travel before it reaches the labium, and this leads to it being less turbulent, due to the physics of airflows.

It does not make sense to expect a large, low pitched ocarina to produce the same range of notes as a very high pitched ocarina. lower pitched ocarinas tend to have fewer holes due to this, and other factors like ergonomics (larger ocarinas are heavier).

The impact of chamber shape on ocarina sounding range

It is often said that 'the shape of an ocarina does not matter', but in my experience as a maker this is not entirely correct. The shape of an ocarina does matter, but the effects it has are not the same as for instruments based on a tube.

In my experience in making these instruments, ocarinas with a chamber that is narrower in diameter and longer can produce a wider range with cleaner sounding high notes.

Longer bodies produce a larger range.

Short, rounded bodies produce a smaller range.

This effect is most noticeable in higher pitched ocarinas. It appears that when the chamber has a narrow diameter (around 3 to 4 centimetres or less), it imposes more resistance to the air moving inside it. The same pitch can be attained with a smaller chamber volume.

As the energy required to maintain sound production is one of the limiting factors on range, reducing the chamber volume in this way can improve sound quality.

Chamber shape can be used as one factor in estimating how a given ocarina will sound and feel. The impact of it is similar to a voicing neck (next heading), reducing the pressure difference between the high and low notes. Longer chambers also tend to bring out more complexities in an ocarina's timbre.

The voicing neck

As you play more ocarinas, you may notice that many of them set back the sound hole into the mouthpiece, inside a constrained volume that I call the 'voicing neck'. The voicing neck traps a plug of air which slows down the oscillations of the chamber, allowing the same pitch to be attained with a smaller chamber.

In practice, voicing necks are mostly found on lower pitched ocarinas, as:

• High pitched ocarinas do not need a separate neck as the the narrow diameter of the chamber creates enough resistance in itself.
• 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.

An ocarina with a more pronounced neck will usually be quieter and more balanced in volume over its range, and one with a less of a neck will have louder high notes in relation to its low notes, and the high notes may sound more airy.

Sound hole shape

You will see ocarinas that have sound holes of different shapes, and the shape of an ocarina's sound hole is the largest factor that influences its timbre. It also has a notable effect on the attainable range.

Teardrop

Teardrop sound holes are among the most commonly found as of writing. They produce a large range, and have a very pure timbre. The larger the distance between the base and tip of the teardrop, the higher the pressure differance will be between the high and low notes.

Rectangular

Rectangular sound holes are most commonly seen on pendant ocarinas, and are rare on transverses. They have a strongly textured, 'reedy' timbre. However they also produce a small sounding range compared to the others. They play with little pressure change between the high and low notes, and are very balanced in volume.

Round

Round sound holes play somewhere between teardrop and rectangular. They produce a relatively textured timbre, but less so than rectangular. They also produce a slightly smaller range than teardrop. They play with a fairly balanced volume and are mostly found on traditional Italian ocarinas.

Oval

Oval shaped sound holes produce a somewhat textured timbre, and can also produce a similar sounding range as teardrop sound holes. Like teardrop sound holes, ovals result in a larger pressure difference between the low and high notes. They are common in Asian made ocarinas.

In general:

• Sound holes that are narrower in their width, and longer, will sound with a more pure tone, require a larger pressure change between the high and low notes, and are able to produce a larger range of notes.
• Wider, shorter sound holes behave in the opposite way, and sound with a more complex tone, smaller range, and less pressure change over the range of the instrument.

Windway bias

The final aspect of ocarina design that is useful to know as a player is windway bias, the relative angle between the windway and the labium. You will see ocarinas ranging between the windway being angled fully towards the outside (external bias), and fully towards the inside (internal bias).

External bias

The windway is angled towards the outside of the chamber,

Neutral bias

The windway is angled directly at the labium.

Internal bias

The windway is angled into the chamber.

In my experience, external bias produces the best sound, and logically this makes sense. The conversion of the air you blow into sound is not completely efficient, and a lot of this air just keeps going in the direction it was going in:

• If the angle of the windway biases the air away from the chamber, it can freely move 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.

The range, tone quality trade-off

The ocarina is a limited instrument. They function best when in harmony with their physical limitations, not in conflict with them. In single chambers that means finding a good compromise between range and balanced timbre.

Standardising all ocarinas, regardless of if they are high or low pitched, towards a single range and fingering system makes very little sense if one understands the nature of the instrument as I have described above. Small soprano ocarinas can easily sound a large range, but as the pitch goes down and chamber volume increases, the attainable sounding range also decreases.

As you have seen, there are other possibilities in ocarina design, such as round and rectangular sound holes, that produce an interesting timbre, but which do not produce a large range. If one focuses only on range, those possibilities are lost.

Multichambered ocarinas are the best option for making an ocarina produce a large range. In practice optimising a lower pitched ocarina maximise its sounding range also means that its timbre is going to lean strongly towards a pure tone.

It is common among ocarina makers to work around the reduced range in lower keys by exploiting the fact that the pitch of the instrument varies depending on how hard it is blown. They attain larger ranges in lower pitched ocarinas by tuning them with a very large pressure change between the high and low notes.

However, this then creates other issues as it makes the high notes vastly louder than the low notes.