Recognising badly tuned ocarinas - how to measure the breath curve

Measuring the breath curve is the main thing that you need to know to tell how well an ocarina is tuned. It's also useful for evaluating several ocarinas and comparing their playing characteristics.

If you play a scale on a well tuned ocarina, the pressure should ramp up gradually between notes with no sudden and arbitrary changes. The two following graphs exemplify a well tuned breath curve and an (exaggerated) poor one.

Directly measuring the pressures in an ocarina's breath curve requires specialist equipment as the pressures involved are very low, fractions of a PSI. But you don't need to measure the absolute pressures directly.

The pressure curve is created when an ocarina is made by tuning sequential notes slightly flat, requiring you to raise your pressure to compensate. Thus these can be measured with a chromatic tuner:

• Finger any note.
• Blow as steady as you can, holding the note in tune.
• Without changing your pressure, raise the finger for the next note in the primary major scale. Do not tongue the transition as doing so can change your blowing pressure.
• The tuner will show that the higher note is playing flat. Note down how many cents it is flat by at the exact moment you lift your finger.

To measure the breath curve of your whole ocarina, begin at your ocarina's lowest note and check each note sequentially, writing down the note and how flat it falls. It is critical that you do not change your blowing pressure, as that will give you a false reading.

Breathing in the correct way, and also the response latency and update rate of the tuner you are using also have a noteable impact on how easily you can measure the breath curve. Those things are discussed later in the article, but for now we will move on to understanding your results.

Understanding your results

Once you have measured the pitch changes across the range of your ocarina, understanding the results is a matter of looking at the difference between sequential values. In a well tuned ocarina, the changes should be about regular across the entire range, like this:

• C: 20
• D: 21
• E: 19
• F: 20
• G: 20
• A: 21
• B: 18
• C: 20

You may notice that the changes increase or decrease gradually between sequential notes, which may be done to shape the breath curve. A gradual reduction towards higher notes for example creates a more linier breath curve, as the base curve is exponential:

• C: 20
• D: 19
• E: 18
• F: 17
• G: 16
• A: 15
• B: 14
• C: 13

Any large irregular changes, such as a sudden pressure increase followed by a decrease, is a tuning error. In practice it would look something like this:

• C: 20
• D: 0
• E: 40
• F: 60
• G: 10
• A: -10
• B: 50
• C: -30

When is a tuning error a problem?

Whether or not an error is a problem depends on how bad it is:

• 5 to 10 cents is not normally noticeable.
• 30 or more will be difficult to compensate for when playing at a moderate tempo.
• Larger errors can be objectively considered bad tuning.

I advise double checking your result as it can be difficult to hold your breath perfectly constant at first. I also recommend taking a few measurements and averaging them.

Traps, blowing technique, and the impact of tuners

There are a few easy mistakes that can cause you to see one reading, when in fact the reality is something different, including your subconscious mind, blowing technique, and the behaviour of certain chromatic tuners.

Subconscious pressure changes

Because ocarinas have a breath curve, when you practice playing you learn to subconsciously change your blowing pressure as you change between notes. Normally its not a problem, but this can easily lead to false readings when you try to measure the breath curve.

If when you lift a finger, your subconscious kicks in, you will unknowing raise your pressure, and will make it appear that your ocarina has a perfectly flat breath curve (zero cents between notes), when in fact it does not.

Being able to deliberately learn to hold your pressure constant is critical. It can help to use a different blowing technique for measuring than the one you use for playing. For example, ramping your pressure up to the first pitch without tonguing.

Also, pay attention to how it feels in your chest when you are exhaling at different rates. This can help you notice when you are changing your blowing pressure.

Using good blowing technique

Using a good blowing technique makes it much easier to blow with consistent pressure, and get accurate measurements of your ocarina's breath curve.

People can breath in two distinct ways, called shallow breathing and diaphragmatic breathing. To get the best possible control you really need to use diaphragmatic breathing, and how to do this is explained on the page 'Blowing an ocarina correctly'.

Using a good tuner

Finally, it is worth noting how the tuner you are using can affect your results. There are three factors:

• Tuners often average pitch over time, a feature called 'needle damping'. Needle damping makes it impossible to get an accurate instantaneous reading, as it smears changes in pitch out over a longer period of time.
• Chromatic tuners do not measure pitch continually, but rather sample it periodically. A tuner with a low sample rate will not show you slight fluctuations in your breath, and thus won't show what is actually happening.
• Most chromatic tuners display cents using an analogue dial instead of a numeric readout. This is not ideal as analogue dials are hard to read quickly.

Thus the characteristics you want in a tuner are:

• High sampling rate.
• low latency.
• Little to no needle damping.
• A numeric cents display in addition to, or instead of, a needle based readout.

Such a tuner makes measuring your ocarina's breath curve far easier. The only tuners I know that meet these requirements are software tuners such as APTuner.