LV15116A - Method for adjustment of electro-accoustic parameters of accoustic vibrator - Google Patents

Abstract

The invention relates to acoustics, in particular to the correction of electroacoustic parameters of acoustic emitters. The proposed technique is intended to improve the sound quality of two or more acoustic systems. The technique is particularly suitable for situations where the synchronization of outgoing and received signals in real time is not possible. The measurement space in the room is determined by the relative delay of the received signals between the channels and the volume of the received signal. Measurements are grouped according to the direction relative to the position and distance of the emitter. The user-specified main listening position adjusts the time delay of the signals so that all channel signals reach the user at the same time, as well as equalizing the sound pressure (volume) of each emitter and weight coefficients for the resulting amplitude-frequency curve are determined by summing the amplitude-frequency curves of the measured amplitudes. The method has been implemented using a measuring microphone (1), a test signal generating and reproducing apparatus (2), two or more acoustic radiators (4 or 5 for multi-channel sound systems) and a received signal amplifier (3). With special test signals, the microphone is evenly moved in the listening area. The measurement space in the room is automatically set and, according to certain regularities, the total amplitude frequency curve for the timbre correction of the sound is created, but the volume and distance of the sound of the sound are adjusted at the main listening position specified by the user.

Description

Description of the invention

The invention relates to acoustics, in particular to the correction of electro-acoustic parameters of acoustic emitters, and may be used to improve sound quality.

A state of the art

There are a number of inventions that offer various solutions for the correction of acoustic emission parameters: the invention (US 5,581,621), which offers a wide range of automated regulation; an invention (US 6,721,428 B1), which provides an amplitude-frequency curve correction in multichannel sound systems using a finite number of parametric equalizer filters; The invention (US2008 / 0089524 AI), which analyzes background sounds, corrects the amplitude frequency curve in multi-channel sound systems.

The patent application US2006 / 0039568 A1 has been chosen as the prototype of the invention, which uses a measuring microphone and a test signal generating device for measuring and subsequent correction of acoustic emission parameters. However, this and none of the above-mentioned inventions can determine the place of measurement in the room. As we know, the amplitude curve (one of the most important sets of acoustic emitter parameters) is highly dependent on the place of measurement in the room, and the measurement in only one room does not give a true picture. Not being able to determine and control the location of measurements in a room, all methods are highly dependent on the user's qualifications and the actions they take.

Object and essence of the invention

The object of the invention is to provide a precise methodology for correcting all electro-acoustic parameters (radiated spectra, volume and time delay) of radiators (sound) for providing qualitative and correct spatial sound in two-channel and multichannel systems. The method is able to determine the place of each measurement to be performed in the room, which allows to control the actions performed by the user and their correctness, as well as provides a reliable and repeatable result. The method offers a space-based measurement solution in situations where real-time synchronization of audio playback and reception parts is not possible.

Methods for realization are: measuring microphone (see Figure 1) [1]; amplifying and analyzing the received signal of the measuring microphone, as well as a test signal generation and sound reproducing apparatus [2], which may be contained in a computer, and an audio amplifier [3] used for amplification of both test signals and sound material; and two (in the case of stereo or two-channel sounding) or several (in the case of multi-channel sound systems) acoustic radiators [4, 5].

When playing special test signals, the microphone is evenly moved in the listening area. The measurement space in the room is automatically set and, according to certain regularities, the total mirrored amplitude frequency correction curve is adjusted for the timbre correction of the sound, but the volume of the sound and the virtual distance are corrected in the main listening position specified by the user.

Detailed description of Tzgudroiuma

The method of the invention provides the following measuring steps: - By uniformly moving the microphone at the height of the listening organs throughout the listening space, the amplitude frequency characteristics of the acoustic emitters are collected and the location of each measurement in the room is automatically determined and maintained. Measurements are grouped according to their distance to the radiators and the direction to the center of the listening position; - When positioning the microphone in the center of the listening position, the total distance of each emitter to the listener and the volume (sound pressure) is determined and adjusted, as well as the priorities for inclusion of the measurement groups determined in the previous stage in the total amplitude frequency curve are selected and the mirror-like correction amplitude frequency curve is created.

Special test signals shown in Figure 2 have been used to measure the amplitude frequency characteristic of the acoustic emitters and to determine the spatial location of the measurements made. Parameters of the standard test signals used are as follows: 1 ms long one-phase signal with a frequency of 1 kHz and a 200 ms pause has been used to determine the distance to the L-channel of the emitter. a distance of 1 ms for a period of 1 kHz and a break of 200 ms has been used to determine the distance to the R channel of the emitter; A 500 ms long upchirp-type test signal has been used to measure the amplitude frequency curve for L channel and 200 ms pause; A 500 ms long upchirp-type test signal has been used to measure the amplitude frequency curve for the R channel. If necessary, both the frequency of the distance determination, the duration of the pause between the test signals and the type and duration of the test of the amplitude frequency measurements can be varied.

An example of the emitted (out) and received (in) signal is shown in Figure 3. The tl is the time interval between the left and right channel test signal start times when they are created. T2 is the time interval between the start of the two detected test signals, but delayH is a delay in the sound processing device (may vary and is unknown, but both channels are the same). For the left channel delayL = delayH + delayA, but for the right channel delayR = delayH + delayB, where delayL and delayR are the total delay of each channel signal (from signal rejection to reception). Delay delayA and delayB are the sound retention in the air from the acoustic emitter to the measuring microphone proportional to the distance to the emitter. Accordingly, in the case of delayR-delayL = tl at the output of the sound equipment, but at the input delayR-delayL = t2, then t2-tl = delayB-delayA, that is, determines the direction of the measurement (vector) in the room. The direction of the vectors at different t2 values is shown in Figure 4.

On the other hand, the energy (loudness / signal level in the microphone) detected by the acoustic emitter decreases as the distance to the (emitter) increases. This correlation is ccponential and, in the case of short distances (a few meters), the relation Lev0 / LevX with sufficient accuracy allows to determine the distance to the emitter, where: LevO is the perceived radiated acoustic power in the immediate vicinity of the acoustic emitter, and LevX is the measured radiated acoustic power at X. The Lev0 / LevX type curve is shown in Figure 5.

Using the predetermined measurement vector space and the polar coordinate system and using the location of the emitter as the center, it is possible to determine the location of the measurement in the room as shown in Figure 6. The point A is the place where the curves created by the vector and the signal level intersect - that is, the place where the measurement is made, and the measurement location is displayed after the closest radiating signal of the L channel (the distance to the second emitter can be used to control the correctness of the measurement and / or accuracy).

An example of using the method

For medium distance radiators (0.7 ... 1.5 m), all measurements corresponding to 0.6 ms> tl-t2> -0.6 ms are counted in the 'central' sector measurement group. If tl-t2> 0.6 ms, the measurement is counted in the 'right' side measurement group. If tl-t2 <-0.6 ms, then the measurement is counted in the left-hand side of the measurement group. Accordingly, all measurements in the 1.2 mS (or about 40 cm) wide corridor between radiators are included in the central measurement group. After levX values, measurements are grouped into three volume beams: middle, middle, and long measurements, creating a total of nine quadrants, as shown in Figure 7. Quadrants 1 ... 3 belong to the 'central' zone, the quadrants 4 ... 6 belong to the 'left' side, and the quadrants 7 to 9 are the quadrants of the 'right' side. If necessary, the number of quadrants can also be chosen by others.

An example of selecting volume groups

If LevO / LevX = l ... 2 to the nearest radiator, the measurement is counted to the nearest gmp (quadrant 1; 4; 7). If Lev0 / LevX = 2 ... 4 to the nearest emitter, the measurement is added to the medium distance measurement group (quadrant 2; 5; 8). If LevO / LevX> 4 to the nearest emitter, the measurement is counted as the distance gmpai (quadrant 3; 6; 9). Other time parameters and the choice of LevO / LevX ratios are also possible according to the size of the room.

By briefly placing the measuring microphone at the most important listening (central) point, the acoustic energy of each emitter at this point and the time interval t2 of the received signal are determined. Using the inverse proportional relationship, the loudness of the emitters is balanced, as well as using the memory buffers of the sound equipment, the original signal through the channels is individually modified (intercepted) so as to minimize the change * tl-t2, ie the sound from both emitted to the listener reaches one (ie, tl = t2 is reached).

The total correction amplitude frequency curve is a mirrored correction curve obtained by calculating a quadrant averaged frequency curve from the amplitude frequency curves of all quadrants, taking into account quadrant 'weight' coefficients.

An example of the choice of weight coefficients is shown in Figure 8. For each 'zone' (right, center, and left), the coefficients are applied as follows: 1/2/4, starting from the nearest quadrant emitted.

The average amplitude curve is calculated for each zone, taking into account the above-mentioned sector coefficients. Taking into account the location of the central point (right or left of the middle), the total amplitude curve is calculated by summing the mean and left zone curves if the center point is to the left of the symmetry axis and summing the mean and right zone curves when the center point is is located to the right of the symmetry axis, taking into account the following 'weight' coefficients between the selected zones: 4 units for the central zone and 1 ... 8 for the edge area. The 'weight' coefficients of the edge area are selected by principle - the further the measurement is from the axis of symmetry, the higher the weight factor. The principles of choosing weight coefficients may be other, based on the fact that higher weight coefficients (i.e., the quadrant amplitude frequency curve has a greater influence on the total amplitude frequency curve) are selected closer to the central listening point.

Claims (2)

Claims A method for optimizing two or more channel sound systems in enclosed spaces and outdoor spaces that provide for the playback, measurement, correction and application of acoustic test signals for work signals, characterized in that: a. test signals are generated such that they contain short average frequency signals for the determination of the distance to the radiators and after a certain period of time the following noise or variable frequency type test signals for the amplitude-frequency curve measurements; b. test signals are designed so that, following their tracking time between channels, it is possible to determine the direction (vector) of measurement in the room relative to the radiators; c. using a polar coordinate system with a center location at the location of the emitter, after a change in the received signal volume, the measuring distance to the emitter is determined; d. using the specified measurement vector and distances to the radiators, the measurement location in the room is determined; e. acoustic measurements are performed throughout the listening space, evenly moving the microphone to the listening organ height; f. the whole sound plane is divided into virtual parts - quadrants, which allow to separate and group measurements by distance to radiators and by direction in relation to the center of the listening place; g. the amplitude-frequency curve of the emitters is corrected by the mirror-correction curve, which is created taking into account the priorities of the virtual part (quadrant) of the space; h. the acoustic power of the emitters and the total correction of the radius of the emitters of the time delay of the signal are balanced at the user point specified in the room. The method of claim 1, further comprising: a. as test signals are used: - to determine distance to radiator L channel -1 ms long signal with 1 kHz frequency and 200 ms pause, - 1 ms signal for 1 kHz frequency and 200 ms pause for amplitude R to channel R - amplitude frequency curves for R channel L - 500 ms long upchirp-type test signal and 200 ms pause, - amplitude frequency curve for R channel - 500 ms long upchirp-beam test signal; b. the measurements are divided into: 3 parts (zones) relative to the center of the room: measurements in the middle part and measurements in two side sections, each of which is divided into 3 parts, measuring the distance of the measurement to the radiators, after the volume of the received signal, which together form 9 quadrants of the space; c. within each zone, quadrant (by distance) priorities are defined by 'weight' coefficients of 1/2/4, starting with the quadrant nearest to the emitters; d. the total correction curve is derived from the sum of the curves of the central curve and its lateral zone which are closer to the user-defined 'center' listening point, including the 'weight' coefficients of the two selected zones: 4 units for the central zone and 1 ... 8 units for the side area, side selecting the area factor directly in proportion to the center point offset from the center zone.