DD273730A1 - CIRCUIT ARRANGEMENT FOR HALL GENERATION - Google Patents

Abstract

The field of application in room acoustics, and in particular in the field of electronic music, is the synthetic generation of Hall in the case of analogue sound signals. The aim is to get a sound reproduction that is appropriate to the habits of the human ear. It is a circuit arrangement created with a replica of Hall from the field of free field sound propagation to the area of the basement Hall is controlled and objective room acoustics, criteria such as direct sound, initial energy and Reverberationsenergie be taken into account. This is achieved mainly by means of a limited number of memories, downstream delta modulators, the outputs of which are controllable via resistors and their common connection via a summer. Fig. 1

Description

embodiment

2 shows the Verschr 'tu ng the resistors with the delta modulators, Figure 3 contains the schematic representation and classification of incoming sound energy at a listener seat, Figure 4 shows the ratio of sound energy for the distance from the sound source for different types of reeds out. The analog audio signal SA passes via the second summer SM 2 to the buzzer / limiting signal SBF, which is connected to the delta modulator DM. Whose output is connected to the first memory S1 for the initial energy E ₁ , in series four more memory S 2-S 5 are connected downstream of the Reverberationsenergie. The output of each memory is applied to the input yes of a delta terminal D1-D5 whose amplifier outputs are connected to resistors R1 to R5. The control inputs Dor resistors R1 to R5 are connected in common to a first summer SM1, which is connected to the filter F. At its output, which is fed back to dt> n second summer SM 2, the generated Hall can be output. The control voltage U _S t is connected via the Yieffrequenzoszillator LFO and the voltage controlled oscillator VCO to the Dsltamodulatoren D1-D5, the memory S1-S5 and the delta modulator DM. The operation of the device is as follows.

One of the most important effects of electronic music is the reverb. Natural reverb (also called revurberation structure) consists of two dominant components: the first discard (or reverberation time) and the statistical reverberation. The first discard is the time between the perception of the original sound and the perception of the first reflections from the walls, which is generally in the range of 20 ... 140 ms. With statistical reverberation is meant the time in which the often reflected sound has decayed by 6OdB compared to the original sound (damping). One criterion for the statistical reverberation is the Hall density. It is 5 to 20 reflections in 10ms and usually grows with the attenuation. In the case of natural reverberation, apart from density fluctuations, a distinction is also made between intensity fluctuations and phase shifts which are dependent on the space and its design and whose superpositions cause frequency changes. In a real room, the impulse-sound test is used to determine the objective room acoustic criteria. In this case, a short sound pulse is radiated from the location of the considered sound source and this then resumed at a listener seat of a microphone (replica head) and visualized by electronic processing on an oscilloscope (see Figure 3). Shown is the direct sound Eo, the initial energy Ei (ie the 1st discards) and the Reverberationsenergia E _n (ie the statistical reverberation). In the area of Reverberationsenergi.i intensity fluctuations occur and at the end there is a Hall density increase. The circuit arrangement now allows a synthetic reproduction of these criteria:

For this purpose, several memory circuits S 1 -S 5 are arranged as a chain, the memories are assigned to the individual areas: memory S1 - initial energy Ei, memory S2-S 5- Revorberationsenergie Er. Each memory is followed by a delta modulator D1-D5. By superimposing the individual demodulator products by the summer SM1 under the condition that two 16K (for S1, S2) and three 64KD RAMS (for S3, S4, SS) are employed, one for detecting Hall reaches necessary density. By means of the feedback control from the output of the filter F back to the summer SM 2, the statistical reverberation can be set. The resulting product gains in naturalness when the oscillator frequency is modulated by the low-frequency oscillator LFO between 0.5 and 1 Hz with 1 to 2%. (A phase shift is modeled.)

Every space requires a different reverberation structure, which manifests itself above all in the attenuation of the reverberation energy E _R. In churches, the statistical reverberation sometimes reaches values up to 7 seconds, in good concert halls they are between 1, 2 and 3 seconds. A distinction is made for different spaces according to the subjective complex of the space or the impression of space, which is closely related to the reverberation time. Under the conditions of real free-field sound propagation, the sound energy decreases with the square of the distance. This means (with Ei = initial energy, I = distance between sound source and measuring location):

In Räi animals in which the sound energy is not completely absorbed, the damping is different from this

Relationship.

FIG. 4 shows the curve course for real free-field sound propagation HF, for linear Kellerhall HK and for an ideal one Sound propagation Hl. To represent the variety of possible attenuation (= hatched area in Figure 4) and both a musical oil out too

be adapted to the respective event space, the delta modulators D1-D5 resistors R1-R5 are connected downstream, whereby the amplifiers of the delta modulators or their output variable can be adjusted. This will make the different

Waiting between the linear Kellerhall HK and real free-field sound propagation HF imitated. In the context of the laws of volume education interested in the evaluation of sound pulses in particular

the transient response of the hearing. For questions of Hall synthesis, however, is also the cooldown of the ghost of

Meaning. It distinguishes z. For example, at what time interval to the direct sound through the delay

simulated reflections amplify and support or blur and disturb, because a subsequent sound stimulus is perceived separately by the ear and processed as new possibly disturbing information when the preceding sound stimulus has decayed sufficiently. The decay of the sound in the ear is frequency independent.

It corresponds to an ear-related reverberation time (level drop by 6OdB) of approximately 0.35 seconds. The volume level

decreases in each case by 9dB in 50ms.

The minimum time interval at which the ear is able to perceive successive different sounds separately is about 5 to 10 ms. In a shorter time sequence, individual sound stimuli merge into an overall impression. Successive similar sound events, z. B. may occur due to sound reflections in a room, has been perceived only at larger time intervals. However, this is also dependent on the intensity of the sound reflections: the greater the time interval of the reflections to the primary sound, the lower the intensities are sufficient to perceive them and possibly to perceive them as a disturbance.

The time interval between a primary schai! and the first reflection arriving at the ear, the exceeding of which is also distracting, is called the blurring threshold. Reflections that arrive at the ear with a time interval that is smaller than the blurring threshold, amplify the sound impression without disturbing it. They are useful reflections. The Blur is at about 50 ms. If the difference between primary sound and reflection increases beyond the blurring threshold to about 100 ms, an echo occurs. This means that the reflection is perceived as a separate Schaliereignis and thus disturbing the hearing.

Taking into account the parameters ear integration zoom and intensity of the reflections listed here, it is therefore possible to select increasing temporal extents from delta-modulator to delta-modulator. The number of delta modulators in a circuit arrangement can be kept relatively low in order to achieve the Hall effect.

On the other hand, the same time intervals can be selected from delta-modulator to delta-modulator and the output variables of the delta-modulators can be adjusted by means of resistors so that they correspond to the described ear integration time within the blurring threshold.

The combination of different delay time, level control of the demodulation products and modulation of Schiebegeschwin quality by the shift register chain and the adjustability of the known components allows the generation of natural-sounding reverb with little effort.

(In the embodiment, five memory circuits and demodulators.)

Claims (2)

Circuit arrangement for generating hives, wherein an analogue sound signal is passed via a sum / Bogrenzungsfilter on a Deltamoduiatcr, characterized in that after the delta modulator (DM), a first memory (S 1) for the lnitialergiö {E |) is arranged, the four more Memory (p 2-S 5} for the Reverberationcenergie (Er) are connected in series, that the output of each memory is fed to the input of each one delta modulator (D1-D5) whose output variables via connected to the outputs resistors (R 1-R5) adjustable in that the set inputs of the resistors (R 1 -R 5) are connected via a first summer (SM 1) to a filter (F), at the output of which via a second summer (SM 2) to the input of the buzzer / limiting filter (SBF), the generated Hall is outputable and that the control voltage (Ust) via a low-frequency oscillator (LFO) and a voltage controlled oscillator (VCO) for clock generation to the delta modulators (D 1-D5), the memory (S 1- S5) and the delta modulator (DM) is connected. For this 2 pages drawings Field of application of the invention The field of application in room acoustics, and in particular in the electronic music industry, is the synthetic generation of Hall in the case of analog sound signals. Characteristic of the known state of the art Known is a device for generating Hall for analog audio signals and a method for their operation (DE-PS 3231925). In this case, an A / D converter for converting the analog audio signals is used in digital audio data, a processing unit for the treatment of digital audio data, a D / A converter for reconverting the treated digital audio data and a device controlling microprocessor. The conversion of the analog audio signals into a binary code takes place. This is stored and called by a microcomputer according to a predetermined program, converted back into a sound signal via a digital-to-analog converter and made audible again. This solution nuchgebildet natural Hall with its characteristic parameters. however, only for selected, previously determined conditions. This method is associated with relatively high costs and high costs, so that devices on this Basic mainly used only in studios or can be used only by a few music groups for which such expenses are possible. Another method uses delta modulation (EP 115215) for the digitization of the audio signal. The resulting, the tone signal equivalent one-dimensional bit pattern is pushed by a D-RAM, which works as a shift register, from input to output with the Abtastfruquenz, which is between 150 ... 1000kHz, and analogized via a delta modulator, whereby the desired delay occurs , Via a feedback loop, the delayed signal is fed back to the input, resulting in multiple repetitions. However, despite the extensive technical effort, this method is not sufficient to produce such a density that the synthetically produced reverberation meets the requirements of the human ear. Object of the invention The aim of the invention is to carry out by simple technical means a synthetic Hall production, by the sound habits of human hearing corresponding sound in wide areas of room acoustics is possible. Explanation of the essence of the invention The object of the invention is to provide a circuit arrangement for Kailerzeugung, wherein an analog tone signal is performed via a Summen7Begrenzungsfilter on a delta modulator by a synthetic replica of Hall from the field dor free field sound propagation to the area of the basement Hall should be made controllable and objective room acoustic criteria, such as direct sound, energy-rich single discards (initial energy) of space limitations and reverberation energy (reverberation energy), which are perceptible at a listener place, to be reproduced. According to the invention this is achieved in that after the delta modulator, a first memory for the initial energy is arranged, the four further memory for the Reverberationsenergie are connected in series. The output of each memory is routed to the input of each delta modulator whose output variables can be regulated by means of resistors connected to the outputs. The control inputs of the resistors are connected via a first summer to a filter, at whose output, which is fed back to the input of the sum / limit filter via a second summer, the generated Hall can be output. The control voltage is connected to the delta modulators, the memory and the delta modulator via a low-frequency oscillator and a voltage-controlled oscillator for clock generation.