Die Natur der Klänge specifications

Category : Lexicon

In principle, natural sound events are based on excitation and decay. Using the example of a guitar string, one can describe the process well. The excitation of the string is carried out by the kinetic energy of a finger or a pick. The resulting initial vibration of the string is a noise that is essentially determined by the stop characteristic (speed, intensity, location); the process starts with the transient of the transient process. This is the first half-wave, which is not a pure sine half-wave but a frequency mixture with many very fast (high-frequency) sound components. However, this looks confusingly similar to a sine half wave. It is the fast rising edge, created by the finger stroke of the guitarist. When a string is plucked or a percussion instrument is struck, the first pressure wave can be both a negative pressure and an overpressure wave. This can be seen very well in music productions. Immediately after excitation, the spring-mass system of the string forces the oscillation frequency in the direction of the resonant frequency of the string. Only after two or three transient pulses does the guitar side vibrate out in the direction of the resonance of the side, until the sound has faded away or the side is plucked again. The vibrational energy is also transmitted on the guitar body and stimulates further resonances there. The first sound waves of the process reach its maximum volume, whereas the subsequent vibrations in the direction of the resonance of the side contain significantly smaller amplitudes (a lower volume). All this in total represents the characteristic sound of this instrument and the way of playing the musician. Depending on the damping of the string, the vibration sounds out quickly or slowly. The following diagrams show the vibration characteristics of a sound body with low damping (left) and high damping (right).

Both graphs show clear amplitude (volume) differences between the initial noises (transient processes, also called transients) and the decay (steady resonance). The settling processes are often louder than the fading out. They contain the highest peak amplitudes (sound level maxima) within the music. The transients have an outstanding significance for auditory perception. They are decisive for the detection and locating of sound events. A continuous tone is practically impossible to locate. Locating is only possible when transients are added to a continuous tone, even of very low intensity (such as in the case of distortions). We locate sound events based on their transient processes. Therefore, it is understandable that during loudspeaker reproduction, the most correct possible conversion of the transient processes has such a strong effect on the spatial imaging. Every new note, every sound of a voice, every note begins with a transient. Music is a transient firework. This is what makes the correct reproduction of the transient processes so important. The continuous tones of different instruments often differ so little that it is not possible to distinguish the instruments. The characteristic of the transient processes is essential for the detection and location of sound sources. An electroacoustic converter must in any case convert signals as they actually occurred in the music! Any attempt to justify reverse polarity of chassis would be illogical. Loudspeakers must convert any input signal, no matter what it looks like, into the equivalent sound pressure structure. The few loudspeakers worldwide that can transform in this way therefore sound more impulse-dynamic, purer, spatially more correct and authentic. From a professional point of view, the correct conversion of transients is part of the correct transmission function of a loudspeaker, but the realization of this claim is "not so easy". The special importance of the transient processes is also due to the fact that under living room conditions there is only a very short time window in which we can listen to the musical content of the sound recordings undisturbed. In a typical listening room, it takes less than 2 ms until the first reflections put an end to the unadulterated listening pleasure. After that, we hear an interaction of direct sound and indirect sound (reflections).

Myro Ocean

The following quote is taken from the book "Hifi hören", Vogel Verlag, 1979, by Heinz Josef Nisius:

"Measurement and listening comparisons show that the impulse behavior of loudspeakers may be more important than an amplitude frequency response linearized to ± 2 dB in terms of the highest possible sound quality, but nevertheless this is not unimportant and also a prerequisite for good Impulse behavior is. To put it bluntly, it can be said that impulse fidelity is one of the most important, at least the most difficult to meet quality criteria of a loudspeaker. The same applies to pickups and amplifiers; it is generally accepted with the amplifier, but not with the loudspeaker.

The fact that the impulse behavior, i.e. the on- and off-oscillation behavior of loudspeakers, is of decisive importance for its sound quality becomes apparent when a monaural piano tape recording is played "the wrong way around", from back to front. Even long-held chords can then no longer be identified as piano sound, although, taken as a whole, "everything is right" in terms of frequency amplitude statistics. However, the temporal relationships of frequency and amplitude are confused. And this distorts the sound."

Graph 1

The signal in the picture on the left shows the signal form, the oscillation sequence of a real musical event in a very simple and therefore still relatively complex, realistic representation, in the form of an oscilloscope representation. We see the pressure fluctuations in their temporal sequence, that is, exactly the event that underlies hearing. This is how our hearing is stimulated. It is precisely these pressure fluctuations in their temporal sequence that make us distinguish this event from the subsequent one...

Graphic 2

It is the sound of a percussion instrument struck. The sound event starts with a few vibrations of very high amplitude (volume) and oscillates out with a low amplitude. The order of the oscillations and their amplitude form the basis for "understanding" the sound event. Only when the vibrations in this form excite our eardrum, we recognize this event in its original form. This is the only way we can recognize and understand language, for example. The illustration of a natural sound structure also clearly shows the enormous difference in the volume of the transients compared to the subsequent vibrations. The transients are many times louder.

Graph 3 This graph represents the same event in reverse order in time. Let's assume that Graph 2 is the vibrational structure of the word XAMBO O. Then the vibration structure of the graph 3 would correspond to the word OOBMAX. Both contain the same letters, but they sound completely different. Another example is a digital code. If the graph above contained the code 0011010111001101, the graph on the left would represent the code 1011001110101100. It is also clear that this would be a completely different result. It is a clear proof that in order to "understand" sound events, we must necessarily be able to hear their exact time-pressure structure. This is the basis for listening!

Mathematical analysis If we make an analysis of the signals, we get their spectral composition. Both signal profiles are identical in terms of their spectral composition. Based on their frequency mixture (equivalent = frequency response), they have exactly the same content, so they would result in the same diagram. However, they sound different. The same applies to the phase position, except that the sign changes in the process. The phase relationships remain the same.

Let's now imagine that loudspeaker model 1 provides the signal sequence of graphic 1 and loudspeaker model 2 provides the signal sequence of graphic 2. Both loudspeaker models would have exactly the same frequency response.

The difference in the vibration sequences of Figures 1 and 2 is small in relation to the differences that speaker models show in comparison. Nevertheless, it is this small difference that is sufficient for us to hear two clearly different sound events.

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Loudspeaker 1 can present sound events in their original form in an easily understandable way.
Loudspeaker 2 reproduces sound events in a practically incomprehensible way.

Die Natur der Klänge