JP2008282172A - Structure monitoring device by means of sound - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a device capable of adequately monitoring a structure by means of sound by frequency-analyzing sound collected by microphone in a structure. <P>SOLUTION: By collecting sound generated accompanying an intrusion at an entrance 2 with a door 2a of a structure 1 and an abnormality in the inside a building by a microphone 3 and removing stationary noise at the entrance 2 and in the inside from the sound, a structure monitoring device acquires a power spectrum ¾X(ω)¾<SP>2</SP>of a target sound signal x(t) which is a function of time t. An operation means 5 for verifying the temporally varying state compares the power spectrum ¾X(ω)¾<SP>2</SP>of the target sound signal x(t) and the collected one in the past to issue an alarm in case the target sound signal is new and unknown. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a monitoring device in a building such as a ship or a land building, and more particularly to a building monitoring device by acoustic analysis that can issue an alarm when an unknown sound or abnormal sound is generated.

In general, for surveillance and security inside the building and near the entrance / exit, a security surveillance video camera is provided, and the suspicious person is discriminated by the judgment of the surveillance person who monitors the video, If security video cameras are installed at many places, doorways, and openings, there is a problem that the cost increases significantly.
In view of this, there has been developed an anti-crime measure by detecting and detecting abnormal sound using an acoustic sensor, but it is difficult to accurately determine abnormal sound on the grounds.
JP 2005-217678 A JP 2002-373386 A

  The present invention provides an apparatus capable of accurately monitoring the inside and outside of a building by sound by appropriately analyzing in real time acoustic information observed by a microphone inside or outside the building. Is an issue.

ここで、Ｙ（ω）：観測信号のスペクトル
ｙ（ｔ）：観測信号
ｅ^-jωt：複素指数関数

ここで、｜Ｘ（ω）｜²：目的信号ｘ（ｔ）のパワースペクトル
｜Ｙ（ω）｜²：観測信号のパワースペクトル
｜Ｎ（ω）｜²：雑音のパワースペクトル
α：サブトラクション係数（１≦α）

In order to solve the above-mentioned problems, the acoustic building monitoring apparatus according to the present invention should always collect environmental sound observed in the building, and collect the sound generated by the occurrence of illegal intruders and abnormal events. A microphone is provided in the building, and the power spectrum | X (of the target acoustic signal x (t) as a function of time t is obtained by removing the environmental sound as noise from the sound collected via the microphone. [mathematical formula-see original document] Calculating means for obtaining [omega]) | ² is provided, and it is assumed that the environmental sound is stationary and is independent of the target acoustic signal x (t). The computing means is configured so that the spectrum | X (ω) | ² is obtained by the formulas [1] and [2] and the similarity is obtained by the formula [3], and the target acoustic signal x (t) of Wah spectrum | X (ω) | ² and then correlation operation and power spectrum of the audio signal taken in the past, there is no correlation with and known acoustic signal low correlation value, that is, the sound is an unknown abnormal sound An alarm means is provided for transmitting an alarm when it is determined.

Where Y (ω): spectrum of the observed signal
y (t): Observation signal
e ^-jωt : Complex exponential function

Where | X (ω) | ² : power spectrum of target signal x (t)
| Y (ω) | ² : power spectrum of the observed signal
| N (ω) | ² : power spectrum of noise
α: Subtraction coefficient (1 ≦ α)

  According to the above-described building monitoring apparatus using sound according to the present invention, environmental sound, which is stationary noise in the building, is collected via a microphone provided in the building, and sound that is not normally generated is collected. Since the calculation means for obtaining the power spectrum of the target acoustic signal x (t) that is a function of time t by collecting the noise and removing the noise from the acoustic is provided, the power of the target acoustic signal x (t) is provided. By comparing the spectrum with a past signal or a known signal, it is easy to determine whether or not it is an abnormal sound. Thus, when the target acoustic signal is determined to be an unknown abnormal sound, an alarm means is used. Alarms are sent out and countermeasures can be taken quickly.

The acoustic building monitoring apparatus of the present embodiment is installed in the main part 1A of the land building 1 as the building shown in FIG. 1 and the main parts 1B and 1C of the marine vessel S as the building shown in FIG. It is what is done.
As shown in FIG. 1 and FIG. 2, in the building 1 or the ship S as a building having the doorway 2a with the doorway 2a, the noise observed in the main parts 1A, 1B, 1C of the building is constantly collected, A microphone 3 is provided inside or outside the building so that sound generated due to entry into the doorway 2 or the like or collapse of the ship S in the hold can be collected.

ここで、Ｙ（ω）：観測信号のスペクトル
ｙ（ｔ）：観測信号
ｅ^-jωt：複素指数関数

ここで、｜Ｘ（ω）｜²：目的信号ｘ（ｔ）のパワースペクトル
｜Ｙ（ω）｜²：観測信号のパワースペクトル
｜Ｎ（ω）｜²：雑音のパワースペクトル
α：サブトラクション係数（１≦α）

Then, as shown in FIG. 3, the power spectrum of the target acoustic signal x (t), which is a function of time t, can be obtained by removing the noise always collected from the sound collected via the microphone 3. Arithmetic means 5 including an acoustic processing device 4 is provided.
That is, the computing means 5 assumes that the noise is stationary and has an independent relationship with the target acoustic signal x (t), and dissimilarity is expressed by [Expression 1], [Expression 2], and [Expression 3]. It is comprised so that it may obtain | require by a type | formula.

Where Y (ω): spectrum of the observed signal
y (t): Observation signal
e ^-jωt : Complex exponential function

Where | X (ω) | ² : power spectrum of target signal x (t)
| Y (ω) | ² : power spectrum of the observed signal
| N (ω) | ² : power spectrum of noise
α: Subtraction coefficient (1 ≦ α)

Further, as shown in FIG. 3, the computing means 5 has a spectrum of past collected acoustic samples in the acoustic sample spectrum database 5a having the power spectrum | X (ω) | ² of the target acoustic signal x (t). A comparison means 5b is provided for comparing the power spectrum | X (ω) | ^{2 of} the target acoustic signal x (t) with an acoustic characteristic different from that of the past sampled acoustic sample. If it is, alarm means 5c for transmitting an alarm is attached.

According to the acoustic building monitoring apparatus of the above-described embodiment, the objective is always in the vicinity of the entrance / exit 2 and the main part 1A (1B, 1C) of the building via the microphone 3 provided inside or outside the building. In addition to collecting environmental sounds that are noise in relation to the sound, sound that is the target sound generated at the entrance 2 and the main part 1A (1B, 1C) of the building is sampled, and from the same sound, the entrance 2 and the main part of the building are collected. Since the calculation means 5 for obtaining the power spectrum | X (ω) | ² of the target acoustic signal x (t), which is a function of the time t, by removing noise in 1A (1B, 1C) is provided. By comparing the power spectrum of the acoustic signal with the spectrum of a known acoustic sample collected in the past in the comparison means 5b, it can be easily determined whether or not it is an abnormal sound. When it is determined that the sound signal is an unknown abnormal sound, an alarm is transmitted by the alarm means 5c, and a countermeasure is quickly taken.

It is as follows when the outline | summary of the building monitoring apparatus by the sound of the above-mentioned present Example is arranged.
(1) The operating environment is composed of one computer device and one microphone.
(2) The program installed in the computer device continues to operate continuously at regular time intervals. The operation is sound observation and acoustic analysis with a microphone and transmission of an alarm.
(3) The analysis consists of firstly understanding the frequency characteristics of the observed sound by performing spectrum analysis, and secondly calculating the correlation with the spectrum of the sound observed in the previous time interval and a known sound (spectrum) sample. Done.
(4) The determination of the occurrence of an abnormality is made by recognizing changes in the surrounding situation based on the magnitude of the correlation value fluctuation and whether or not the sound is unknown.
(5) The characteristic operation of this device is performed as a report (automatic transmission of e-mail) by recognition of abnormality or a code output to an external output (RS232C port, etc.) of the computer.

  The feature of the building monitoring apparatus by sound of the present embodiment is that the change of the ambient sound is determined not by the magnitude of the sound but by the specific change of the frequency, and that the sound is not a known sound but an unknown sound. It is a point to judge by recognizing. In other words, in this system, when an intrusion or abnormality occurs in the monitored range, the system does not react when a loud sound is generated, but it is an unknown sound that the sound quality has changed. The above-mentioned intrusion and the occurrence of abnormality are recognized.

It is explanatory drawing which shows schematic structure of the building monitoring apparatus by sound as one Example of this invention. It is a perspective view which shows the other example using the apparatus of this invention. It is a block diagram which shows the flow of an effect | action in the apparatus of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Building 1A, 1B, 1C Main part of building 2 Entrance / exit 2a Door 3 Microphone 4 Sound processing device 5 Calculation means 5a Database 5b Comparison means 5c Alarm means S Ship

Claims (1)

A microphone is provided in the structure in order to observe and immediately analyze the sound sensed in the building in order to detect the occurrence of abnormal noise, and from the sound observed through the microphone, a steady state in the structure can be obtained. Arithmetic means are provided for analyzing the target acoustic signal x _n (t) as a function of time t by removing the noise, the noise being stationary in one continuous time interval and the target acoustic signal. as is independent of x _n (t), the power spectrum of the object audio signal _{x n (t) | X (} ω) | obtained by ² [expression 1] and [expression 2] where the required successive The computing means is configured to obtain a correlation coefficient between the power spectrum of the next target acoustic signal x _{n + 1} (t) observed at the time interval and the power spectrum of the known sound by the formula [3]. , The above correlation Wherein the warning means to the alert of noise generated when the number is low is provided, a structure monitor Acoustic.

Where Y (ω): spectrum of the observed signal
y (t): Observation signal
e ^-jωt : Complex exponential function

Where | X (ω) | ² : power spectrum of target signal x (t)
| Y (ω) | ² : power spectrum of the observed signal
| N (ω) | ² : power spectrum of noise
α: Subtraction coefficient (1 ≦ α)

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