How air temperature affects the ocarinas pitch

Like all wind instruments the pitch produced by an ocarina is temperature sensitive. The voicing mixes the players warm breath with ambient air from the environment and the internal temperature stabilizes between the two.

Western instruments are tuned to a standard called 'concert pitch' or 'A440'. When an ocarina is made it is designed to play to this standard at a given air temperature. They will play sharp in warmer environments and flat in colder ones. Consequently 'concert pitch' is meaningless unless you know the temperature it was tuned at. Pure ocarinas are tuned for an ambient temperature of 20C.

The pitch of an ocarina changes linearly at about 1 cent per degree. This value is not absolute as it does depend on how much the players breath is able to warm the ocarina. Lower pitched ocarinas are harder to warm as they have a significantly larger internal volume.

As the ocarinas pitch is also affected by blowing pressure these changes can be compensated for by changing your breath pressure up or down. There is a limit to this compensation though.

The instruments sensitivity to these changes varies across the sounding range. The low notes are the most sensitive and can easily be bent up or down by several semitones. As you ascend the scale this sensitivity decreases considerably. The highest note is the least sensitive to pressure changes. Changing the pitch by a given number of cents requires a much larger pressure change than is required on the low notes. They also has the smallest scope for pitch bending, about plus/minus 50 cents.

If you have an ocarina this can be observed easily. Finger a low note and over blow it until the ocarina squeaks, track the starting note and the highest note. Next repeat the exercise on the highest note, you will not be able to push it anywhere near as far.

The following tool visualizes what is going on. The green area depicts the pressure range in which an ocarina is able to make sound. The line depicts the breath curve. If you lower the temperature slider and attempt to compensate the breath curve will become notably steeper. If you raise the temperature and lower the pressure the high end sags. If the curve goes above the green area this would represent the ocarina squeaking.

It is best to minimize pitch compensations as it also affects the ocarinas tone especially on the high notes. If an ocarina is pushed sharp it's tone will have a rougher timbre. If the high notes are under-blown they will sound more airy.

There are a number of ways of dealing with this. In a cold environment you can warm the body of the ocarina in front of a heater. Ceramic has considerable thermal mass and will radiate this energy, warning the air in the ocarina. In hot environments you can do the opposite, put the ocarina in the fridge.

If you need to play in a very cold or warm environment for a long time a better option is to allow your pitch to drift away from concert. In a live performance tune your accompaniment to you. In a recording modern Digital Audio Workstations allow the pitch to be raised or lowered without affecting it's speed.

Measuring an ocarinas tuning

As ocarinas are temperature sensitive you need to know how to check there tuning relative to concert pitch. How to do this is described here.

Exercises

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