Resonators for room acoustic – why?
The double function of the resonator
Resonance is an omnipresent phenomenon of utmost importance which decisively influences physical occurrences. Bodies which are especially trimmed for their resonance capacity and which therefore are employed to give resonance are called resonators. Resonators are used especially with stringed instruments. Here, a specially tuned resonating body fulfils its task as a “resonance amplifier”. The sound which is generated by the energetically excited string for this purpose with the help of a coupling bridge stimulates the body of a violin or a guitar resp. the sounding board of a piano etc. to forced vibrations. In this sense the string of a string instrument has a forcing function.
The process of resonance is thus a “transference of energy” from, if you like, a “forcing oscillating” to a “forced oscillating” body. The energy of the forced oscillation of the resonator is thereby stored in a specific form of absorption. Whilst with stringed instruments, the function of resonators as “sound giving” is apparent, they also universally fulfil the function as absorbing sound receivers. In this sense, it is decisively important that the absorption performance of the resonator determines its delivery performance – both functions are thus causally coupled in this manner. Therefore resonators return exactly the same amount of sound energy into the room as they are able to absorb. Since the resonance reflection results from the resonance oscillation and since the resonance oscillation can be described as a physical system of “standing waves” with nodes and antinodes, concrete statements can be made about the nature and direction of the resonance reflection of a slab.
Because the resonance reflection results from the vibrations of the “antinodes” in the system of “standing waves” which are spread over the entire surface of the slab, its intensity at any given point is small. However its “laminar expansion” is that much the greater. The acoustic effect is accordingly non-concentrated, therefore “gentle” and yet unweakened. The resonance reflection of a slab exhibits two preferred directions: on the one hand at a degree of 90° to the front side of the slab and, on the other hand, at a degree of 90° to the back side of the slab.
The incident sound is reflected at a part (gray) and spread to another part on the resonance in the plate element (brown)
The resonant panel member has become a source of sound, and thus emits 50% of the acquired sound energy back into space.
This causes the sound to “tire” more slowly, thereby increasing the sustaining quality of the sound. Sound absorbing measures become necessary in rooms where an overly long reverberation time causes the sound to blur. In such a case, convention says to apply sound dampening materials.But dampening by itself reduces the substance of the sound in the room. It makes the room “dry” and poor sound-poor. Sound-poor rooms in their turn quickly seem insipid, cold and therefor not very vitalizing. Therefor, in order to encourage a good sound in the room, measures taken to reduce the reverberation by means of destroying sound also require countermeasures to preserve the sound. A room acoustic solution which limits itself to destroying and reflecting sound is fundamentally a compromise. As it is the nature of compromises to go on the cost of sometimes the one and sometimes the other party, the optimum in room acoustic can never be achieved in this way. Because resonators simultaneously cover the most essential spaceacoustic requirements, such reductions from the optimum are generally avoidable with their assistance.
In this light, the use of resonators for room acoustic seems the ideal solution. Until now however, such a resonance solution for room acoustic was hampered by the fact that the resonance performance of conventional resonators based on cavity resonance only affected a very limited frequency range. Conventional resonators thereby slightly distort the reflected sound and so are in opposition to the demands for a natural sound and balance. With the help of the newly developed and patented methode of resonance spectral tuning, we now have this problem under control. Since our panel resonators have been especially tuned so that the origin of all important parts of their own spectrums are ideal, they cover, with their resonance performance, the complete acoustically relevant frequency range in a hitherto unattained way.
Ignatius panel resonators produce a nearly equal resonace performance in all desired frequencies.
These are brand new possibilities in room acoustic.