The lounuet is a friction instrument from New Irland, now extinguished. It mimics the hornbill bird and frogs. Three lamellas, or plates, are cut out from a wooden block:
It is played by rubbing the hands over the plates:
Although the plates can have different eigenmodes to vibrate in, here a Finite-Element Method (FEM) model of the lowest modes,
during rubbing mainly the lowest mode is produced, which is the tone sounding.
Interestingly, tourist instruments built today look like the original lounuet, still they do not sound. When rubbing the original one, here one of the Überseemuseum in Bremen, Germany, the sound is very loud! The reason is, that the chambers below the plates act as resonators. If the chambers are built with the wrong size, the instrument does not sound.
Still this does not mean that below each plate a resonance chamber is built fitting the pitch of the plate above it. With a microphone array (Acoustic Camera) the air vibration in the chambers can be measured. Here are measurements for the three plates. On the right side is the vibration when the plates are rubbed, on the left side when one is knocking on the plates, only for comarison. Here for the higest plate on the left of the lounuet:
For the middle plate:
And for the lowest plate:
In all cases the vibration pattern is a complex combination of several chambers. Only then the instrument sound so loud, mimicing the sound of animals.
Bader, R.: Outside-instrument coupling of resonance chambers in the New-Ireland friction instrument lounuet, Proc. Mtgs. Acoust. 15, 035007 http://dx.doi.org/10.1121/2.0000167 , 2012.
Heintze, D.: Lounuet. Notizen zum neuirländischen Reibidiophon. [Lounuet.
Notes about the friction idiophone from New Ireland.] In: In: D. Deterts, D. Heintze, & S. Seybold (eds.): Musik – Ethnologie – Museum. Freundesgabe für Andreas Lüderwaldt. Jahrbuch XVII, Überseemuesum Bremen, Schünemann, 69-104, 2011.
Sounds can be found here:
Messner, F.: Friction blocks of New Ireland. In: A. L. Kaeppler & J. W. Love (eds.): Garland Encyclopedia of World Music. vol. 9: Australia and the Pacific Islands. Routledge, London, 380-382, 1998.