Automatic acoustic signal setting method for space monitoring device using acoustic signals

Abstract

The present invention discloses a method for automatically setting an acoustic signal of a space monitoring device using an acoustic signal, which is a technology for automatically setting the acoustic signal emitted from the space monitoring device so as to more accurately grasp changes in the physical conditions of the monitored space.

Description

[Technical Field]

[0001] The present invention relates to a method for automatically setting an acoustic signal for a space monitoring device using an acoustic signal, and relates to a technology for automatically setting the acoustic signal emitted from the space monitoring device so as to more accurately grasp changes in the physical situation of the monitored space. [Background technology]

[0002] Various sensors and devices are used to detect intrusions into indoor spaces, fires, gas leaks, etc. In recent years, with the development of IoT technology, systems have been developed that can remotely detect various conditions in indoor spaces, such as the operation status of heating and cooling systems and whether windows are open, and take subsequent measures accordingly.

[0003] These various sensing technologies generally include CCTV, IR camera, vibration sensor, gas sensor, etc. In the case of conventional technologies, a separate sensing device is required for each situation such as intrusion, fire, gas, etc., so that in order to monitor various indoor space situations, many sensing devices are required, which results in high costs for building the equipment and considerable power consumption.

[0004] To solve the above problems, a technique has recently been proposed in which an acoustic signal is emitted and the indoor space situation is grasped based on the change in the received acoustic signal.

[0005] One type of device that uses acoustic signals to understand spatial conditions is the frequency response sensor, which emits and receives sounds (acoustic signals) of multiple frequencies and detects changes in temperature and other things within the monitored space by analyzing changes in the sound pressure or phase spectrum of the received acoustic signals.

[0006] Figure 1 is a graph showing an example of a sound pressure spectrum measured by a frequency response sensor at time t1, and Figure 2 is a graph showing both the sound pressure spectrum measured by the frequency response sensor at time t1 and the sound pressure spectrum measured at time t2 after t1. By measuring the horizontal movement of the sound pressure spectrum over time as shown in Figure 2, i.e., the frequency shift S, it is possible to detect temperature changes in the monitored space. Therefore, accurate measurement of the frequency shift is important in order to accurately detect temperature changes in the monitored space.

[0007] The accuracy of measuring frequency shift can be improved as the difference between the maximum and minimum values ​​of sound pressure that change with frequency increases. For example, in the case of a sound pressure spectrum that is expressed as a generally flat curve due to a small difference between the maximum and minimum values ​​of sound pressure level, it is difficult to accurately measure the degree of shift even if a shift in the sound pressure spectrum occurs, making it difficult to accurately grasp the temperature change in the space based on this. As an extreme example, if the spectrum is expressed as a single horizontal line because there is no change in sound pressure value with frequency, it is actually impossible to measure the amount of shift even if a shift in the sound pressure spectrum occurs. Therefore, it is necessary to appropriately adjust the frequency of the emitted acoustic signal so that the difference between the maximum and minimum values ​​of sound pressure level is at least a certain value.

[0008] Furthermore, although it has been described above that the emitted acoustic signal must be appropriately adjusted from the viewpoint of ensuring the difference between the maximum and minimum sound pressure values, the emitted acoustic signal can be optimized by applying various criteria other than the difference between the maximum and minimum sound pressure values.

[0009] However, even if the emitted acoustic signal is optimized by applying at least one determination criterion, if the arrangement of furniture or devices in the monitored space changes, if the position or direction of the space monitoring device changes, if the temperature changes with the change of seasons, etc., the previously set acoustic signal may no longer be the optimal acoustic signal. Therefore, if various factors such as the shape of the monitored space, the arrangement of furniture or devices, the temperature, and the position and direction of the monitoring device change, the emitted acoustic signal must be reset to an appropriate one accordingly.

[0010] It is extremely troublesome to manually reset the audio signals every time in response to changes in the various factors mentioned above, and it is particularly difficult for non-expert users to reset the audio signals to appropriate ones. Summary of the Invention [Problem to be solved by the invention]

[0011] The present invention has been devised to solve the problems of the prior art described above, and aims to eliminate the hassle of having to reset an appropriate acoustic signal every time when sensing a spatial situation through a spatial monitoring device that uses acoustic signals, depending on various factors such as the shape of the target space, the installation location of the monitoring device, and changes in the placement of fixed objects in the target space.

[0012] In particular, we aim to solve the problem of the difficulty for non-expert users to directly find and reset an acoustic signal suitable for a target space.

[0013] The objects of the present invention are not limited to those described above, and other objects and advantages of the present invention not described above can be understood from the following description. [Means for solving the problem]

[0014] One embodiment of the method for automatically setting an acoustic signal for a space monitoring device according to the present invention can include an acoustic signal emitting step of emitting an acoustic signal to a monitored space; an acoustic signal receiving step of receiving the acoustic signal from the target space; a space frequency response measuring step of measuring a frequency response of the space based on the received acoustic signal; an acoustic signal resetting decision step of judging the measured frequency response of the space based on set judgment conditions and deciding whether to reset the acoustic signal to be emitted; and an acoustic signal resetting step of changing and resetting the acoustic signal to be emitted in accordance with the decision to reset the acoustic signal.

[0015] As an example, the judgment conditions in the acoustic signal resetting judgment step may include at least one of measurement stability, spectrum variability, appropriateness of frequency resolution, or distinguishability from noise.

[0016] As an example of a condition for determining the stability of measurement, the acoustic signal emission step through the space frequency response measurement step can be repeated, and the acoustic signal resetting determination step can evaluate the stability of the measurement based on the similarity between the frequency responses of the multiple spaces repeatedly measured, and determine whether or not to reset the acoustic signal.

[0017] As an example of a spectral variability judgment condition, the acoustic signal resetting judgment step can evaluate the spectral variability by comparing the difference between the maximum and minimum values ​​of the spectrum or the degree of scattering in the measured spatial frequency response with a reference range, and determine whether to reset the acoustic signal.

[0018] As an example of a condition for determining the adequacy of frequency resolution, the acoustic signal resetting determination step can evaluate the adequacy of frequency resolution based on the slope of a spectral waveform in the measured spatial frequency response, and determine whether or not to reset the acoustic signal.

[0019] As an example of a condition for determining whether the acoustic signal is distinguishable from noise, the acoustic signal resetting determination step may evaluate the distinguishability from noise by comparing the measured spatial frequency response with a previously acquired spatial frequency response or with noise measured without emitting an acoustic signal, and determine whether to reset the acoustic signal.

[0020] Furthermore, the acoustic signal resetting step can reset the acoustic signal to be emitted by adjusting at least one of the frequency of the emission start point, the frequency of the emission end point, or the acoustic signal emission duration for a single-sound acoustic signal.

[0021] Alternatively, the acoustic signal resetting step may reset the emitted acoustic signal by adjusting at least one of the frequency interval, the center frequency, or the number of frequencies for an acoustic signal of a complex sound containing a plurality of frequency components.

[0022] Going one step further, the acoustic signal emitting step through the frequency response measuring step are performed for each of the plurality of retained acoustic signals, and the acoustic signal resetting decision step can include a step of calculating a performance value for each acoustic signal based on at least one judgment criterion of measurement stability, spectral variability, appropriateness of frequency resolution, or distinguishability from noise present in the target space in the frequency response of the space measured corresponding to each acoustic signal, and a step of comparing the performance values ​​for each acoustic signal to decide whether or not to reset the acoustic signal to be emitted.

[0023] Another embodiment of the method for automatically setting an acoustic signal for a space monitoring device according to the present invention may include an acoustic signal emitting step of emitting an acoustic signal to a monitored space; an acoustic signal receiving step of receiving an acoustic signal from the monitored space; an acoustic signal resetting decision step of judging the received or real-time received acoustic signal based on a set decision condition and deciding whether to reset the acoustic signal to be emitted; and an acoustic signal resetting step of changing and resetting the acoustic signal to be emitted in accordance with the decision to reset the acoustic signal. [Effects of the Invention]

[0024] According to the present invention, the acoustic signal can be automatically reconfigured to achieve optimal detection performance, taking into account various factors such as the shape of the target space, the installation location of the space monitoring device, and changes in the placement of fixed objects in the target space.

[0025] In particular, the problem of users finding it difficult to find an appropriate acoustic signal can be resolved, and an acoustic signal that can exhibit optimal performance can be automatically set.

[0026] Such automatic reconfiguration of the acoustic signal allows for more precise sensing of the situation in the target space.

[0027] The effects of the present invention are not limited to those described above, and other effects not described above will be clearly understood by those skilled in the art to which the present invention pertains from the following description. [Brief explanation of the drawings]

[0028] [Figure 1] 1 is a graph showing an example of a sound pressure spectrum measured by a frequency response sensor at time t1. [Figure 2] 1 is a graph showing an example of a sound pressure spectrum measured by a frequency response sensor at time t1, and an example of a sound pressure spectrum measured at time t2 after time t1. [Figure 3] 3 is a flowchart illustrating an embodiment of an automatic acoustic signal setting method according to the present invention. [Figure 4] 1 is a configuration diagram showing an embodiment of a space monitoring device for realizing an automatic acoustic signal setting method according to the present invention; [Figure 5] 1 is a configuration diagram showing an embodiment of an acoustic signal processing unit of a space monitoring device that realizes the present invention. [Figure 6] 3 is a flowchart illustrating an embodiment of an audio signal resetting determination process in the audio signal automatic setting method according to the present invention. [Figure 7]10 is a flowchart illustrating an embodiment of a measurement stability determination condition in the acoustic signal automatic setting method according to the present invention. [Figure 8] 10 shows an example of evaluation of measurement stability in the acoustic signal automatic setting method according to the present invention. [Figure 9] 1 is a flowchart illustrating an embodiment of a spectral variability judgment condition in the acoustic signal automatic setting method according to the present invention. [Figure 10] 1 shows an example of spectral variability evaluation in the acoustic signal automatic setting method according to the present invention. [Figure 11] 1 is a flowchart illustrating an embodiment of a condition for determining the appropriateness of frequency resolution in the automatic acoustic signal setting method according to the present invention. [Figure 12] 10 shows an example of evaluation of the appropriateness of the frequency resolution of an acoustic signal in the acoustic signal automatic setting method according to the present invention. [Figure 13] 1 is a flowchart showing an embodiment of a condition for determining whether a signal is distinguishable from noise in the method for automatically setting an acoustic signal according to the present invention. [Figure 14] 1 shows an example of the operational relationship of a space monitoring device for determining distinguishability from noise in the automatic acoustic signal setting method according to the present invention. [Figure 15] 1 is a flowchart illustrating an embodiment of a process for selecting an optimal audio signal from a plurality of audio signals stored in the audio signal automatic setting method according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0029] In the present invention, when a space monitoring device monitors the situation of a monitored space using an acoustic signal, a method for automatically optimizing the emitted acoustic signal for more accurate detection is proposed. In this regard, a method for automatically setting an acoustic signal according to the present invention will be described.

[0030] The acoustic signal automatic setting method according to the present invention can include a first method for determining whether to reset the acoustic signal based on the measured spatial frequency response, and a second method for determining whether to reset the acoustic signal based on the acoustic signal itself received in the time domain.

[0031] In relation to the first method, FIG. 3 is a flowchart showing an embodiment of an automatic acoustic signal setting method according to the present invention.

[0032] The space monitoring device 100 can emit an acoustic signal to a target space to be monitored (S100) and receive an acoustic signal from the target space (S200). The emitted acoustic signal can be an acoustic signal used for monitoring the target space thereafter. Alternatively, the emitted acoustic signal can be a test acoustic signal for determining the noise level of the target space, the shape of the target space, and the location of fixed objects placed in the target space.

[0033] The acoustic signal may be a single-sound acoustic signal whose frequency changes over time, a complex-sound acoustic signal containing multiple frequency components whose frequency does not change over time, a complex-sound acoustic signal containing multiple frequency components whose frequency changes over time, or an acoustic signal that alternates between a single-sound acoustic signal and a complex sound.

[0034] The space monitoring device 100 receives an acoustic signal from a target space and measures the frequency response of the space (S300), and determines whether to reset the acoustic signal to be emitted into the target space based on the measured frequency response of the space and a predetermined determination condition (S400). Here, the determination condition for whether to reset the acoustic signal may be selectively or multiplely set from various determination conditions such as measurement stability, spectral variability, appropriateness of frequency resolution, or distinguishability from noise present in the target space, for the measured frequency response of the space.

[0035] If it is determined that the acoustic signal to be emitted into the target space does not need to be reset, the space monitoring device 100 can maintain the existing acoustic signal and continue to sense the situation in the target space. If it is determined that the acoustic signal to be emitted into the target space needs to be reset, the space monitoring device 100 can change and reset the acoustic signal to be emitted into the target space based on the reset determination result (S500), and can sense the situation in the target space using the changed acoustic signal.

[0036] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings. However, the present invention is not limited or restricted by the embodiments.

[0037] DETAILED DESCRIPTION OF THE INVENTION For the purposes of explaining the invention, its operating advantages, and objects attained by its practice, the following description will be given with reference to an example of a preferred embodiment of the invention.

[0038] First, the terms used in this application are merely used to describe specific embodiments and are not intended to limit the present invention, and singular expressions can include plural expressions unless the context clearly dictates otherwise. Furthermore, in this application, terms such as "include" or "have" are intended to specify the presence of features, numbers, steps, operations, components, parts, or combinations thereof described in this specification, and should be understood not to preclude the presence or possibility of addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0039] In the description of the present invention, if it is determined that a detailed description of related known structures or functions may obscure the gist of the present invention, the detailed description will be omitted.

[0040] The present invention discloses a method for automatically setting the acoustic signal to be emitted for more accurate measurement in a space monitoring device using an acoustic signal.

[0041] A space monitoring device to which the present invention is applied emits an acoustic signal into a target space, receives the acoustic signal from the target space, and can grasp the space situation based on the measured frequency response of the space.

[0042] The spatial frequency response referred to in the present invention can be explained as follows: If a target space is considered as a kind of closed circuit, and an acoustic signal is emitted as an input signal and then received as an output signal, elements such as frequency-specific sound pressure or frequency-specific phase of the received acoustic signal can be defined as the "spatial frequency response."

[0043] As an example of expressing the frequency response of such a space, a graph can be displayed with frequency on the horizontal axis and the sound pressure of the received sound on the vertical axis, and the phase element can also be displayed on the vertical axis instead of the sound pressure element.

[0044] Since the frequency response of a space changes depending on the physical characteristics of the space, the physical situation of the space can be inferred using the frequency response of the space, and further, the change in the physical characteristics of the space can be grasped using the pattern in which the frequency response of the space changes. In this case, the greater the difference in the frequency response of the space due to the difference in the physical characteristics of the space, or the greater the change in the frequency response of the space caused by the change in the physical characteristics of the space, the more accurately the physical situation of the space can be sensed using the frequency response of the space.

[0045] FIG. 4 is a block diagram showing an embodiment of a space monitoring device for implementing the automatic acoustic signal setting method according to the present invention.

[0046] The space monitoring device 100 to which the present invention is applied may include an acoustic signal emitting unit 110, an acoustic signal receiving unit 130, an acoustic signal processing unit 150, a situation determining unit 170, and the like.

[0047] The acoustic signal emitting unit 110 can emit an acoustic signal into a target space by including a speaker 111. The acoustic signal emitting unit 110 can emit a single sound acoustic signal whose frequency changes over time, a complex sound acoustic signal containing a plurality of frequency components whose frequency does not change over time, a complex sound acoustic signal containing a plurality of frequency components whose frequency changes over time, or an acoustic signal in which the single sound acoustic signal and the complex sound alternate.

[0048] In addition, the acoustic signal emitting unit 110 can emit an acoustic signal through one speaker or through multiple speakers. When emitting acoustic signals through multiple speakers, the same acoustic signal can be emitted or different acoustic signals can be emitted from each speaker.

[0049] The acoustic signal receiving unit 130 can receive an acoustic signal in a target space by including a microphone 131. The acoustic signal receiving unit 130 can receive an acoustic signal through one microphone or through multiple microphones. In addition, the acoustic signal receiving unit 130 can include various measuring devices capable of measuring sound pressure, sound intensity, etc.

[0050] The acoustic signal processing unit 150 can provide an acoustic signal to be emitted into a target space to the acoustic signal emitting unit 110. In addition, the acoustic signal processing unit 150 can receive the acoustic signal received by the acoustic signal receiving unit 130 and reconfigure the acoustic signal to be emitted in consideration of various factors of the target space so that optimal sensing performance can be obtained.

[0051] The situation determination unit 170 can determine the situation of the target space based on the frequency response of the space. When various situation changes occur in the target space, such as object movement, temperature change, or air movement, the received acoustic signal changes accordingly, and the frequency response of the space measured using the received acoustic signal also fluctuates. The situation determination unit 170 can determine what situation change has occurred in the target space based on whether or not the measured frequency response of the space has changed, the degree of change, the change pattern, etc.

[0052] The present invention can automatically set the acoustic signal to be emitted into a target space so that optimal detection performance is exhibited when monitoring the target space using the space monitoring device described above.

[0053] FIG. 5 is a block diagram showing an embodiment of the acoustic signal processing section of a space monitoring device that realizes the present invention.

[0054] The acoustic signal processing unit 150 may include a control unit 151, a frequency response measurement unit 153, a reset determination unit 155, an acoustic signal adjustment unit 157, and the like.

[0055] The control unit 151 can control the acoustic signal emitting unit 110 to emit an acoustic signal into the target space, and can control the acoustic signal receiving unit 130 to receive an acoustic signal in the target space.

[0056] The frequency response measurement unit 153 may measure a spatial frequency response based on the acoustic signal received by the acoustic signal receiving unit 130. The frequency response measurement unit 153 may measure a spatial frequency response by converting the received acoustic signal into a frequency domain using a Fourier transform algorithm or a fast Fourier transform algorithm. For example, the frequency response measurement unit 153 may measure a sound pressure spectrum by converting the received acoustic signal into a sound pressure value in the frequency domain.

[0057] The reset decision unit 155 can determine whether to reset the acoustic signal to be emitted by determining the frequency response of the received acoustic signal or the measured space based on preset decision conditions.

[0058] Preferably, the reset determination unit 155 may start the procedure for resetting the audio signal when a preset event occurs. For example, various cases may be set as events for determining whether to reset the audio signal, such as when there is a user's request for resetting the audio signal, when initial power is supplied to start the operation of the space monitoring device 100, when a period of a certain time interval arrives, when the operation of the space monitoring device 100 is suspected to be unstable, when new noise enters the target space, when space characteristics such as a change in the arrangement of fixed objects in the target space change, etc.

[0059] Furthermore, while the space monitoring device 100 emits an acoustic signal to monitor the target space, it can determine whether to reset the acoustic signal in a non-monitoring time band, which is an interval time band between periodic monitoring operation time bands. For example, the time band can be divided in units of one second, and the target space monitoring operation and the acoustic signal reset decision can be performed alternately.

[0060] The reset determination unit 155 may determine whether to reset the acoustic signal by determining the frequency response of the received acoustic signal or the measured space based on various criteria such as measurement stability, spectral variability, appropriateness of frequency resolution, or distinguishability from noise present in the target space. That is, the reset determination unit 155 may determine whether to reset the acoustic signal by determining the acoustic signal itself in the time domain based on various criteria while receiving the acoustic signal, or may convert the received acoustic signal into a signal in the frequency domain and determine the frequency response of the measured space based on various criteria to determine whether to reset the acoustic signal.

[0061] Furthermore, the reset determination unit 155 may store a plurality of different acoustic signals, calculate a performance value for each of the stored acoustic signals based on a determination condition, and compare the calculated performance values ​​to select an optimal acoustic signal. To this end, the reset determination unit 155 may store a plurality of different acoustic signals each having a single sound whose frequency changes over time, a plurality of different acoustic signals each having a complex sound whose frequency does not change over time, a plurality of different acoustic signals each having a complex sound whose frequency changes over time, and a plurality of different acoustic signals each having a single sound and a complex sound alternating.

[0062] The acoustic signal adjustment unit 157 can adjust and reset the acoustic signal to be emitted based on the determination result of the reset decision unit 155 .

[0063] If the acoustic signal to be emitted is a single-tone acoustic signal whose frequency changes over time, the acoustic signal adjustment unit 157 can reset the acoustic signal to be emitted by adjusting at least one of the frequency of the emission start point, the frequency of the emission end point, or the acoustic signal emission duration.

[0064] Alternatively, if the acoustic signal to be emitted is an acoustic signal of a complex sound containing multiple frequency components, the acoustic signal adjustment unit 157 can reset the acoustic signal to be emitted by adjusting at least one of the frequency interval, the center frequency, or the number of frequencies.

[0065] Furthermore, when the resetting determination unit 155 holds a plurality of different acoustic signals and selects an acoustic signal having optimal performance from among the held acoustic signals, the acoustic signal adjustment unit 157 can receive the selected acoustic signal from the resetting determination unit 155 and reset it to the acoustic signal to be emitted.

[0066] The acoustic signal reset by the acoustic signal adjustment unit 157 is provided to the control unit 151, and the control unit 151 can control the acoustic signal emission unit 110 to emit the reset acoustic signal into the target space.

[0067] Previously, the automatic acoustic signal setting method according to the present invention was described with reference to the embodiment shown in FIG.

[0068] As described above, the present invention can automatically set an acoustic signal to improve the situation detection performance for the target space, but the process of determining whether to reset the acoustic signal will be considered in accordance with a specific embodiment.

[0069] FIG. 6 is a flowchart showing an embodiment of an audio signal resetting decision process in the audio signal automatic setting method according to the present invention.

[0070] The space monitoring device 100 measures the frequency response of the space based on the received acoustic signal (S300). As an example, the received acoustic signal can be converted into the frequency domain via a Fourier transform (FT) or a fast Fourier transform (FFT) to measure the frequency response of the space in the frequency domain.

[0071] As another example, when a single sound signal whose frequency changes over time is emitted, sound of a specific single frequency is emitted at a specific time, so the space monitoring device 100 can measure the frequency response of the space by immediately converting the sound pressure value or phase value measured according to the emission time into a sound pressure value or phase value according to the emission frequency. In other words, in this case, since the sound pressure value according to the frequency is measured almost in real time, a separate Fourier transform is not required.

[0072] As described above, the spatial frequency response can be expressed by elements such as frequency-specific sound pressure or frequency-specific phase of the received acoustic signal, and as an example, it can be displayed as a graph with frequency on the horizontal axis and sound pressure on the vertical axis.

[0073] For convenience of explanation, the following description will be given using a spectrum showing a change in sound pressure at each frequency relative to a spatial frequency response as an example. However, in the present invention, the spatial frequency response is not limited to a change in sound pressure at each frequency.

[0074] Once the spatial frequency response is measured (S300), it is possible to determine whether to maintain the existing acoustic signal (S450) or reset to a new acoustic signal (S460) because the sensing performance of the existing acoustic signal has deteriorated, based on various criteria, such as determining the stability of the measurement (S410), determining the variability of the spectrum (S420), determining the appropriateness of the frequency resolution (S430), and determining whether the acoustic signal can be distinguished from noise (S440).

[0075] Here, the execution order of each judgment condition can be changed, and depending on the situation, only a specific judgment condition can be selected to determine whether or not to reset the audio signal.

[0076] Each of the determination conditions will be described in more detail according to the embodiment.

[0077] FIG. 7 is a flowchart showing an embodiment of the repeatability judgment conditions in the automatic acoustic signal setting method according to the present invention.

[0078] When selecting an acoustic signal, if the frequency response of a space is measured to be similar within a certain level range when there is no change in the situation in the same target space, the stability of the space monitoring device can be said to be ensured. If the frequency response of a space is measured to be different even when there is no change in the situation in the same target space, the reliability of the space monitoring device may be lost. However, the reliability or measurement stability of a space monitoring device may vary depending on, for example, the frequency of the emitted acoustic signal. Therefore, the present invention aims to ensure the stability of the space monitoring device by automatically setting an acoustic signal that can maintain measurement stability.

[0079] To determine the stability of the measurement, the space monitoring device 100 emits acoustic signals into the target space a set number of times (S110), receives the acoustic signals from the target space (S210), and measures the frequency response of the space for each acoustic signal (S310) to obtain a spectrum. The correlation or similarity between the frequency response spectra can be analyzed (S413) to evaluate the stability of the measurement for the emitted acoustic signals (S415).

[0080] An example of the stability of the measurement will be described with reference to FIG. 8, which shows a sound pressure spectrum as a spatial frequency response.

[0081] Assume that a first sound pressure spectrum 211 as shown in (a) of Figure 8 and a second sound pressure spectrum 212 as shown in (b) of Figure 8 are obtained by repeatedly emitting and receiving the same acoustic signal into a target space.

[0082] When the correlation between the first sound pressure spectrum 211 and the second sound pressure spectrum 212 is analyzed to determine the degree of similarity, the similarity can be evaluated to be greater than a reference value, so that measurement stability can be satisfied. When the measurement stability is satisfied at a certain level by repeatedly evaluating the measurement stability for the selected acoustic signal, the selected acoustic signal can be determined as an acoustic signal suitable for monitoring the target space.

[0083] As a different case, let us assume that the first sound pressure spectrum 211 as shown in Figure 8(a) and the third sound pressure spectrum 213 as shown in Figure 8(c) are obtained by repeatedly emitting and receiving the same acoustic signal into the target space.

[0084] When the correlation between the first sound pressure spectrum 211 and the third sound pressure spectrum 213 is analyzed to determine the degree of similarity, it may be determined that the spectrum is below a reference value and is not similar, so that the stability of measurement cannot be satisfied. In this case, the selected acoustic signal may be determined as an acoustic signal that is not suitable for monitoring the target space, and the space monitoring device 100 may perform a process of resetting the acoustic signal.

[0085] In this way, by evaluating the stability of repeated measurements of the acoustic signal emitted into the target space, it is possible to determine whether the acoustic signal is suitable for monitoring the target space, and to reset the acoustic signal based on the determination results.

[0086] FIG. 9 is a flowchart showing an embodiment of the spectral variability judgment condition in the acoustic signal automatic setting method according to the present invention.

[0087] Taking the sound pressure spectrum as an example of the frequency response of a space, it is possible to grasp temperature changes in the monitored space by measuring the frequency shift in the sound pressure spectrum. However, the accuracy of measuring the frequency shift improves as the difference between the maximum and minimum sound pressure values, which change with frequency, increases. If the difference between the maximum and minimum sound pressure values ​​is too small and the sound pressure spectrum appears as a flat curve, it is difficult to accurately measure the frequency shift. Therefore, it is necessary to select an acoustic signal whose difference between the maximum and minimum sound pressure values ​​in the sound pressure spectrum is greater than a certain level.

[0088] When selecting an acoustic signal, if the acoustic signal is emitted into a target space, received, and the sound pressure spectrum measured based on the received signal has a sound pressure width greater than a reference range, it can be determined that the spectrum has variability. Conversely, if the sound pressure values ​​of the measured sound pressure spectrum vary slightly depending on the frequency, less than the reference range, it is determined that the spectrum does not have enough variability, and such an acoustic signal is not suitable for sensing the spatial situation.

[0089] In the present invention, the accuracy of the space monitoring device can be improved by automatically setting the acoustic signal so that the spectral variability is above a certain level. Referring to Figure 9, to determine the spectral variability, the space monitoring device 100 identifies the maximum and minimum values ​​in the spectrum for the measured frequency response of the space (S421). Then, the difference between the maximum and minimum values ​​is calculated (S423) and compared with a reference range (S425), thereby evaluating the spectral variability for the emitted acoustic signal (S427).

[0090] An example of spectral variability assessment will be described with reference to FIG. 10, which shows a sound pressure spectrum as a spatial frequency response.

[0091] Assume that an acoustic signal is emitted to and received from a target space, and the fourth sound pressure spectrum 221 shown in Fig. 10(a) is acquired. If the maximum value MAX and minimum value MIN of the sound pressure value in the fourth sound pressure spectrum 221 are determined and the difference between the maximum value MAX and the minimum value MIN is calculated, the difference value is represented as H1. If the difference value H1 satisfies a set reference range, the spectral variability can be satisfied. If the spectral variability for the selected acoustic signal is satisfied, the selected acoustic signal can be determined as an acoustic signal suitable for monitoring the target space.

[0092] As another example, let us assume that an acoustic signal is emitted to and received from a target space, and the fifth sound pressure spectrum 222 shown in Figure 10(b) is acquired. The maximum and minimum sound pressure values ​​MAX and MIN in the fifth sound pressure spectrum 222 are identified, and the difference between the maximum and minimum values ​​MAX and MIN is calculated. The difference value is represented as H2. If the difference value H2 does not satisfy a preset reference range, the spectral variability may not be satisfied. In this case, the selected acoustic signal may be determined to be unsuitable for monitoring the target space, and the space monitoring device 100 may perform a process of resetting the acoustic signal.

[0093] In the above, the difference between the maximum and minimum values ​​of the spectral sound pressure values ​​is used as a criterion for determining the variability of the spectrum. However, other criteria for determining the variability of the spectrum may also be used, such as the degree of scattering of the sound pressure values, such as the variance, standard deviation, mean deviation, or quartile deviation.

[0094] By evaluating the variability of the spectrum of the acoustic signal emitted into the target space in this way, it is possible to determine whether the acoustic signal is suitable for monitoring the target space, and to reset the acoustic signal based on the determination result.

[0095] FIG. 11 is a flowchart showing an embodiment of a condition for determining the appropriateness of frequency resolution in the automatic acoustic signal setting method according to the present invention.

[0096] When selecting an acoustic signal, even if the above-mentioned spectral variability is satisfied, if the appropriate frequency resolution for the acoustic signal is not satisfied, errors may be included in the spatial frequency response measurement.

[0097] Frequency resolution refers to the distance between a specific frequency and the closest frequency that can be distinguished. When measuring the spatial frequency response by emitting a complex sound signal containing multiple frequency components, the measured sound pressure spectrum can be expressed as an integer number of frequencies as shown in Figure 10. In this case, the distance between frequencies can directly become the resolution.

[0098] If the emitted sound is in the form of a sine sweep, in which a single frequency varies linearly over time, the measured sound pressure spectrum may be displayed as a curve rather than an integer number of points. However, even if the spectrum is displayed as a curve, there is actually a resolution, which is the ability to distinguish a specific frequency from its nearest neighboring frequencies. In this case, the resolution is determined by the performance of the components constituting the monitoring device, the operating conditions of the monitoring device, the data processing conditions, etc. For example, an acoustic signal may be recorded using a specific sampling rate during the acoustic signal reception stage, and in this case, the sampling rate may affect the resolution. Alternatively, for example, a spectrum may be displayed using a "moving average" technique as a method of removing unnecessary noise from the measured sound pressure spectrum. In this case, the resolution may be determined by the size of the interval over which the moving average is calculated.

[0099] If there are too many peaks in a frequency band (window) of a spectrum, the spectrum cannot be accurately represented unless sufficient resolution is ensured. In such cases, by modifying the acoustic signal so that the frequency resolution is appropriate, the frequency response of the space can be accurately measured.

[0100] For example, comparing Figures 12(a) and 12(b), the difference between the maximum and minimum sound pressure values, i.e., the variability of the spectrum, is the same in both cases. However, the spectrum in Figure 12(a) is relatively flat, i.e., the number of peaks within the window is small, while the spectrum in Figure 12(b) has many peaks within the window. Therefore, the spectrum in Figure 12(a) can be expressed using 20 points, for example, with 20 frequencies. However, to properly express a spectrum like that in Figure 12(b), it would need to be expressed using 200 points, for example, with 200 frequencies, and therefore the frequency interval or frequency resolution would need to be narrower.

[0101] In the present invention, the appropriateness of the frequency resolution can be evaluated and the acoustic signal can be reset accordingly. If the frequency resolution is evaluated to be inappropriate, the center frequency can be changed and the appropriateness of the frequency resolution can be evaluated again for frequencies in another band, or the center frequency can be left unchanged and the resolution (e.g., frequency interval) itself can be adjusted.

[0102] As an example, the appropriateness of frequency resolution can be evaluated based on the spectral slope (the numerator is the frequency width, and the denominator is the sound pressure width). For example, when a sound pressure spectrum is expressed as sound pressure values ​​(ordinate coordinate values) for N frequencies (abscissa coordinate values) spaced a frequency distance d apart, if the average absolute value of the spectral slope is small, i.e., if the spectrum is flat as shown in Figure 12(a), the shape of the spectrum can be properly represented even if the frequency distance d is large. On the other hand, the larger the average absolute value of the spectral slope, i.e., if the frequency distance d is sufficiently narrow so that the spectrum has many peaks as shown in Figure 12(b), the spectrum can be properly represented.

[0103] When a spectrum is expressed as sound pressure values ​​for N frequencies, there are N-1 absolute values ​​p of the difference in sound pressure values ​​between adjacent frequencies, and if the sum of all N-1 p's is divided by the window width d*(N-1), this becomes the average absolute value of the slope of the spectral waveform.On the other hand, when a spectrum is expressed as a curve, if the sum of all the absolute values ​​of the differences between the maximum and minimum values ​​for the many peaks in the spectrum is divided by the window width, this becomes the average absolute value of the slope of the spectrum.

[0104] 11, to select an acoustic signal based on the appropriateness of the frequency resolution, the space monitoring device 100 determines a window for the frequency response of the measured space (S431), determines the slope of the spectral waveform (S433), and calculates the average value of the slope absolute value (S435).Then, the calculated average value can be compared with a reference range (S437) to evaluate the appropriateness of the frequency resolution (S439).

[0105] In this way, by evaluating the appropriateness of the frequency resolution of the acoustic signal emitted into the target space, it is possible to determine whether the acoustic signal is suitable for monitoring the target space, and to reset the acoustic signal based on the determination result.

[0106] FIG. 13 is a flowchart showing an embodiment of the conditions for determining whether a sound signal is distinguishable from noise in the method for automatically setting an acoustic signal according to the present invention.

[0107] If the noise present in the target space and the emitted acoustic signal are similar to each other above a certain level, causing interference between the acoustic signal and the noise, the acquired frequency response of the space may not accurately reflect the physical state of the monitored space. Therefore, the acoustic signal must be set to avoid noise zones present in the target space.

[0108] In addition, when multiple space monitoring devices are installed in a target space, if they emit acoustic signals with similar frequencies, the acoustic signals emitted from different space monitoring devices may function as noise, so it is necessary to set each space monitoring device to emit acoustic signals with different frequencies.

[0109] In the present invention, it is possible to grasp the noise in a target space, evaluate the distinguishability between the emitted acoustic signal and the noise, and set an acoustic signal that can avoid noise sections.

[0110] The process for determining the distinguishability from noise will be explained using the two examples shown in (a) and (b) of FIG.

[0111] 13(a) shows an example in which a spatial frequency response whose reliability has been confirmed in advance is used. The space monitoring device 100 can extract (S441a) a spatial frequency response whose reliability has been confirmed by measuring it in a noise-free environment when determining whether it can be distinguished from noise.

[0112] Then, the spatial frequency response measured by emitting and receiving the acoustic signal at the present time is compared with the spatial frequency response in a reliable state (S443a), and the degree of noise inflow and its distinguishability can be evaluated (S445a).

[0113] As another example, (b) of Fig. 13 shows a case where interference between an acoustic signal and noise is grasped while alternating between an acoustic signal emission period and an acoustic signal non-emission period. As shown in Fig. 14, the space monitoring device 100 measures the acoustic signal of the target space in the S period and measures the noise of the target space in the N period while alternating between an S period in which an acoustic signal is emitted and an N period in which an acoustic signal is not emitted (S441a). Then, the acoustic signal measured in the S period and the noise measured in the N period are compared to grasp the degree of frequency interference (S443a), and the distinguishability from noise can be evaluated (S445a).

[0114] If the mutual frequency bands of the acoustic signal and the noise are not the same, the selected acoustic signal can be determined as an acoustic signal suitable for monitoring the target space. Conversely, if the mutual frequency bands of the acoustic signal and the noise are the same to a certain level or more, interference occurs between the acoustic signal and the noise, so the selected acoustic signal can be determined as an acoustic signal not suitable for monitoring the target space, and the space monitoring device 100 can perform a process of resetting the acoustic signal.

[0115] In this way, by evaluating the distinguishability of the acoustic signal emitted into the target space from noise, it is possible to determine whether the acoustic signal is suitable for monitoring the target space, and to reset the acoustic signal based on the determination result.

[0116] Based on the evaluation of the various criteria described above, the space monitoring device 100 can reconfigure the acoustic signal.

[0117] When the space monitoring device 100 resets a single-tone acoustic signal, it can reset the emitted acoustic signal by adjusting at least one of the frequency of the emission start point, the frequency of the emission end point, or the acoustic signal emission duration.

[0118] In addition, when the space monitoring device 100 resets an acoustic signal of a complex sound containing multiple frequency components, it can reset the emitted acoustic signal by adjusting at least one of the frequency interval, the center frequency, or the number of frequencies.

[0119] Furthermore, in the present invention, the space monitoring device 100 can have a plurality of acoustic signals, evaluate each acoustic signal based on a judgment condition, and select the most suitable acoustic signal.

[0120] In this regard, FIG. 15 is a flow chart illustrating an embodiment of a process for selecting an optimal audio signal from among a plurality of retained audio signals.

[0121] The space monitoring device 100 can select one of the stored acoustic signals (S610), emit the selected acoustic signal into a target space, and receive an acoustic signal from the target space (S620).

[0122] The space monitoring device 100 can measure a frequency response of the space based on the received acoustic signal (S630) and evaluate the acoustic signal based on a judgment condition (S640), where the judgment condition can include at least one of the above-mentioned measurement stability, spectral variability, appropriate frequency resolution, or distinguishability from noise.

[0123] Then, the space monitoring device 100 may select another acoustic signal and repeatedly evaluate the acoustic signal based on the evaluation conditions depending on whether or not the evaluation of some or all of the stored acoustic signals has been completed (S650). For example, the space monitoring device 100 may extract and evaluate acoustic signals whose center frequencies are spaced apart by a predetermined interval from the stored acoustic signals.

[0124] Here, the multiple acoustic signals held by the space monitoring device 100 may be various types of acoustic signals, such as multiple different acoustic signals each consisting of a single sound whose frequency changes over time, multiple different acoustic signals each consisting of a complex sound containing multiple frequency components whose frequency does not change over time, multiple different acoustic signals each consisting of a complex sound containing multiple frequency components whose frequency changes over time, and multiple different acoustic signals each consisting of alternating single sounds and complex sounds.

[0125] The space monitoring device 100 may evaluate a plurality of acoustic signals and select an optimal acoustic signal (S660). For example, the space monitoring device 100 may calculate a performance value for each acoustic signal based on at least one of the following criteria: measurement stability of the spatial frequency response measured for each acoustic signal, spectral variability, appropriateness of frequency resolution, or distinguishability from noise. The optimal acoustic signal may then be determined by comparing the calculated performance values ​​for each acoustic signal. For example, the final performance value may be calculated by multiplying or adding the evaluation values ​​for each evaluation criteria for each acoustic signal, or by assigning weights to each evaluation criteria and multiplying or adding the evaluation values ​​for each evaluation criteria in consideration of the weights. The optimal acoustic signal may then be determined by comparing the final performance values ​​for each of the plurality of acoustic signals.

[0126] If the selected optimal acoustic signal is the acoustic signal that was previously emitted, there is no need to reset the acoustic signal, but if it is different from the acoustic signal that was previously emitted, the space monitoring device 100 can reset the acoustic signal to be emitted as the selected optimal acoustic signal (S670).

[0127] Through this process, the space monitoring device 100 can reset the acoustic signals among the plurality of acoustic signals stored therein to the acoustic signal most suitable for monitoring the corresponding target space, and monitor the target space.

[0128] The above describes an example of the first method for determining whether to reset an acoustic signal based on one or more criteria using a measured spatial frequency response. However, while it is possible to use the measured spatial frequency response, i.e., a spectrum expressed in the frequency domain, as in the first method, to determine whether to reset an acoustic signal, it is also possible to apply a second method for determining whether to reset an acoustic signal using the acoustic signal itself received in the time domain.

[0129] The second method can also be applied to a complex sound signal containing multiple frequency components. However, for convenience, the following description will be based on the case where a single sound signal whose frequency changes over time is used.

[0130] The second method can determine whether to reset an acoustic signal by judging an acoustic signal received for a certain period of time or an acoustic signal in the time domain received in real time based on criteria such as measurement stability, spectral variability, appropriate frequency resolution, and distinguishability from noise.

[0131] For example, to determine the stability of the measurement, the similarity between time-domain acoustic signals received repeatedly a preset number of times can be determined to evaluate the stability of the measurement, and based on this, it can be determined whether to reset the acoustic signal.

[0132] As an example, in order to determine the variability of the spectrum, the difference between the maximum and minimum values ​​of the sound pressure, etc. received in real time in the time domain can be determined and compared with a reference range to evaluate the variability of the spectrum.

[0133] As another example, to determine the appropriateness of frequency resolution, the slope of the sound pressure fluctuations received over a certain period of time in the time domain can be grasped and compared with a reference range, thereby evaluating the appropriateness of frequency resolution.

[0134] As another example, the distinguishability of the received acoustic signal from noise can be evaluated by comparing it with previously received and acquired acoustic signals, or with noise received in a section where no acoustic signal is emitted.

[0135] When determining whether to reset the acoustic signal based on various criteria as described above, the determination step does not necessarily have to be performed after measuring the spatial frequency response using the first method. In some cases, it may be possible to determine whether to reset the acoustic signal by receiving the acoustic signal according to the second method without going through the spatial frequency response measurement process, or by evaluating the acoustic signal itself in the time domain received in real time based on the criteria.

[0136] According to the present invention described above, it is possible to automatically reconfigure acoustic signals to achieve optimal detection performance, taking into account various factors such as the shape of the target space, the installation location of the space monitoring device, and changes in the placement of fixed objects in the target space.

[0137] In particular, the problem of users finding an appropriate acoustic signal can be resolved, and an acoustic signal that can provide optimal performance can be automatically set. This automatic re-setting of the acoustic signal allows for more accurate sensing of the situation in the target space.

[0138] The above description merely exemplifies the technical concept of the present invention, and various modifications and variations may be made by those skilled in the art without departing from the essential characteristics of the present invention. Therefore, the embodiments described herein are for illustrative purposes only, and are not intended to limit the technical concept of the present invention. The technical concept of the present invention is not limited by these embodiments. The scope of protection of the present invention should be interpreted by the following claims, and all technical concepts within the scope equivalent thereto should be interpreted as being within the scope of the invention.

Claims

1. A method for automatically setting a monitoring sound signal of a space monitoring device, comprising: a candidate acoustic signal emitting step of emitting a candidate acoustic signal into a target space to be monitored; an acoustic signal receiving step of receiving an acoustic signal of the target space; a performance value calculation step of calculating a performance value of the candidate sound signal based on a judgment condition, the candidate acoustic signal emitting step, the acoustic signal receiving step, and the performance value calculating step are performed for each of a plurality of candidate acoustic signals; a setting step of setting one candidate acoustic signal, determined by comparing performance values ​​of each of the plurality of candidate acoustic signals, as the monitoring acoustic signal.

2. a frequency response measurement step of measuring a spatial frequency response of the target space using the received acoustic signal; 2. The method of claim 1, wherein the spatial frequency response measurement is performed for each of the plurality of candidate acoustic signals.

3. 3. The method according to claim 2, wherein in the performance value calculation step, the judgment conditions include at least one of measurement stability, spectral variability, appropriateness of frequency resolution, and distinguishability from noise.

4. the candidate acoustic signal emitting step, the acoustic signal receiving step, and the frequency response measuring step are repeatedly performed for the candidate acoustic signals; 3. The method according to claim 2, wherein in the step of calculating a performance value for the candidate acoustic signal, measurement stability is calculated as the performance value based on similarity between a plurality of spatial frequency responses repeatedly measured for the candidate acoustic signal.

5. In the step of calculating the performance value of the candidate acoustic signal, 3. The method of claim 2, wherein the spectral variability is calculated as a performance measure for the candidate acoustic signal by comparing the difference between maximum and minimum values ​​or the degree of scattering with a reference range.

6. 3. The method according to claim 2, wherein in the performance value calculation step, the appropriateness of frequency resolution is calculated as the performance value based on a slope of a spectral waveform in the measured spatial frequency response.

7. 3. The method of claim 2, wherein in the step of calculating the performance value of the candidate acoustic signal, the distinguishability from noise is calculated as the performance value by comparing the measured spatial frequency response with a spatial frequency response previously obtained or by analyzing noise measured without emitting an acoustic signal.

8. 3. The method of claim 2, wherein the plurality of candidate acoustic signals include acoustic signals of complex sounds having a plurality of frequency components, and the acoustic signals of the complex sounds differ from each other in at least one of a frequency interval, a center frequency, and a number of frequency components.

9. the step of emitting the candidate acoustic signal and the step of receiving the acoustic signal from the target space are repeatedly performed for each of the plurality of candidate acoustic signals; 2. The method of claim 1, wherein in the performance value calculation step, measurement stability is calculated as the performance value based on similarity between acoustic signals repeatedly received in the time domain for the candidate acoustic signals.

10. 2. The method of claim 1, wherein in the step of calculating the performance value of the candidate acoustic signal, the distinguishability of the candidate acoustic signal from noise is calculated as the performance value by comparing the received acoustic signal with a previously received acoustic signal or by analyzing noise measured without emitting an acoustic signal.

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