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This phenomenon creates complex sounds and is underlined by the fact that a combination of harmonics can
produce additional tones, known as interference or residual tones. All of these tiny sound portions contribute
to the sound of certain instruments. The human ear, which is highly sensitive, can detect even minimum
changes in the harmonic structure of a sound.
By experiencing the CD quality of 18 bit-converters etc., we have made considerable advances toward the
naturalness of sound, yet still recordings do not sound like the music in a concert hall. Why is there a
difference?
Here, the keyword is intelligent hearing: the visual contact with the musicians enables us to concentrate our
attention on a certain instrument which results in an intensification of the sonic experience. The listener
sitting in front of a speaker system lacks this spatial experience and at the same time the visual feedback
aspect of listening to live music. The perceived positioning of instruments is made even more difficult since
the dispersion of the sound is not homogeneous, i.e., widely panoramic, but usually reduced to two sound
sources.
In particular, the loss of upper harmonics during the transmission of the sound additionally affects the perceived
positioning of the instruments and the transmission of room ambiance. The reason for this loss in sound
quality is the inadequacy of the sound recording and reproduction processes.
Each link in the transmission chain - from the microphone via mixers, effects devices, tape recorders amplifiers
etc., to the loudspeakers - causes a loss in sound quality. Each time the sound is processed, it becomes
audibly less natural.
5.3 On Psycho-Acoustic Devices
In the field of what is known as psycho-acoustics, numerous terms such as enhancer, exciter, psycho-
acoustic processor, psycho-dynamic processor, clarifier etc., are commonly used. What do these terms
actually mean? The following chapter will shed some light on this.
Although the psycho-acoustic effect of enhancers and exciters etc., has been known for several decades,
the function of these devices has been deliberately surrounded in mystique, to increase their appeal.
However, it is fairly clear that all devices in this field are based on certain technically repeatable methods of
functioning. Basically, three principles apply:
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Sound improvement by means of dynamic frequency correction.
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The generation of a wider sound with the help of phase shifting with respect to delay times.
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The enrichment of the program material with artificially generated harmonics.
Independently of each other, each of these methods produces a certain effect which is perceived as a
subjective enhancement within the sound.
These methods are described in more detail in the following:
5.3.1 Frequency Correction
The boosting or cutting of certain frequency ranges is the simplest form of sound modification. Equalizers
can correct the sonic image in order to produce a sound that is more pleasing to each taste.
So-called treble boosters achieve this effect by emphasizing the high frequencies, which the listener perceives
as a transparent sonic image.
Within the BEHRINGER ULTRAFEX PRO, any frequency correction is combined with a frequency-dependent
phase shift, which results in a sound that is warmer and more musical.
5.3.2 Phase Shifting
The term phase shift describes the displacement of a signals phase in relation to its point of origin. As a
matter of principle, the phase shift produces a delay within the signal.
If the delayed signal is added to the original signal, the resultant signal becomes wider. Below time delay
values of 20 msec. the brain perceives the delayed arrival of the two signals as the arrival of one signal,
which results in the desired pulse enlargement effect, sometimes called 3-D effect by other manufacturers.
5. TECHNICAL BACKGROUND
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