Every handpan player knows it: notes that just don't want to sound right. They sound muffled, stifled or dissonant. This is due to sound impedance, a phenomenon that can negatively affect the beautiful sound of your instrument.
- Quiet sound: Affected tones sound significantly quieter.
- Muffled sound: The sound is muffled and not very transparent.
- Dissonances: Unpleasant dissonances occur in some places.
What is sound impedance?
Put simply, sound impedance is the difficulty with which sound waves travel through a medium. In the case of the Handpan, this medium is the air-filled bowl of the instrument.
The diameter and depth of the bowl influence the sound impedance. Certain pitches can suffer if the sound waves of these tones cannot vibrate cleanly through the bowl. Instead of sounding clear and defined, interference occurs.
This interference occurs when the sound waves "cancel each other out". Wave peaks and troughs overlap unfavorably, so that the actual sound becomes weaker or sounds completely dead. Technical terms for this phenomenon are phase shift, wave interference or phase cancellation.
Which sounds are most affected?
To summarize, the secondary areas of sound degradation in handpans are less severe than the primary areas, but should still be considered.
- Primary areas:
- 19 inch (48.26 cm): C5 and B4
- 20 inch (50.8 cm): B4 and Bb4
- 21 inch (53.34 cm): Bb4 and A4
- Secondary ranges:
- 19 inches (48.26 cm): G#5, sometimes A#5, C#6 and D#6
- 20 inches (50.8 cm): G5, sometimes A5, C6 and D6
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21 inches (53.34 cm): F#5, sometimes G#5, B5 and C#6
What can be done about sound impedance?
Subsequent optimization
While intervention in the construction of existing instruments is generally not advisable, there are possibilities for subsequent optimization:
- Damping elements: our approach uses small damping elements made of closed cell foam. Similar to acoustic foam panels in recording studios, these specifically placed "baffles" are intended to interrupt the problematic sound waves inside the handpan without dampening the overall sound. The positioning of these elements requires some experience and precision work, as even experienced players can sometimes spend an hour finding the optimum placement.