阅读说明：本技术 值得保护的城市声景观品质自动监测方法 (Urban sound landscape quality automatic monitoring method worthy of protection ) 是由 马蕙 朱国风 贾怡红 于 2021-09-04 设计创作，主要内容包括：本发明公开了一种值得保护的城市声景观品质自动监测方法,首先对值得保护的城市声景观进行录音采集；把采集的声音信号转换为数字信号,再与不同类型、不同声级大小的噪声信号进行混缩得到混缩噪声信号；对所有信号指代声景观品质的指标进行计算,从而获得每一个采集片段的指标参量；以原声景观信号作为对照组,以混缩噪声信号作为评价组,将二者进行比较评价,得到每一个采集片段中声景观品质受到影响程度的评价等级；然后建立决策树分类模型,基于得到的决策树分类模型的分支条件,获取指代声景观品质的指标的不同组合方式与声景观品质受影响程度之间的关系,用于实践中对声景观品质监测,对声景观的受影响程度进行分类识别。(The invention discloses a method for automatically monitoring the quality of urban sound landscape worth protecting, which comprises the following steps of firstly, recording and collecting the urban sound landscape worth protecting; converting the collected sound signals into digital signals, and then mixing and compressing the digital signals with noise signals of different types and different sound levels to obtain mixed and compressed noise signals; calculating indexes of all signals indicating the quality of the sound landscape so as to obtain index parameters of each acquisition segment; taking the original sound landscape signal as a comparison group and the mixed noise signal as an evaluation group, and comparing and evaluating the original sound landscape signal and the mixed noise signal to obtain the evaluation grade of the degree of influence on the sound landscape quality in each acquisition segment; and then establishing a decision tree classification model, and acquiring the relation between different combination modes of indexes referring to the sound and landscape quality and the influenced degree of the sound and landscape quality based on the branch conditions of the decision tree classification model, wherein the relation is used for monitoring the sound and landscape quality in practice and classifying and identifying the influenced degree of the sound and landscape.)

1. A method for automatically monitoring the quality of urban sound landscape with value protection is characterized by comprising the following steps:

the method comprises the following steps: recording and collecting different quality states of the urban sound landscape worth protecting;

step two: converting the sound signals collected in the step one into digital signals to obtain original sound landscape signals, and mixing and compressing the original sound landscape signals and noise signals of different types and different sound levels to obtain a plurality of mixed and compressed noise signals interfered by noise; calculating indexes of all signals indicating the quality of the sound landscape so as to obtain index parameters of each acquisition segment;

taking the original sound landscape signal without the mixed noise as a comparison group, taking the mixed noise signal after the mixed noise as an evaluation group, and carrying out pairing comparison evaluation on the original sound landscape signal without the mixed noise and the mixed noise signal to obtain the evaluation level of the degree of influence on the sound landscape quality in each acquisition segment;

step four, establishing a decision tree classification model based on the data sets in the step two and the step three, and further dividing the step into the following steps;

4-1, reading a data set and preprocessing the data set;

4-2, training a decision tree model, namely inputting a part of data in the data set as training data and the other part of data as test data into the decision tree model for training; the training of the decision tree model is divided into the following processes: firstly, setting a training data set of a first node as D, and calculating a kini index of the existing characteristics to the data set; secondly, selecting the feature with the minimum Keyny coefficient and the corresponding segmentation point as the optimal feature and the optimal segmentation point from all possible features A and all possible segmentation points a of the feature A, generating two sub-nodes from the current node according to the optimal feature and the optimal segmentation point, and distributing the training data set into the two sub-nodes according to the feature; then, recursively calling the two steps for the two child nodes until a stop condition is met; finally, generating a decision tree model;

4-3, classifying the change degree of the sound and landscape quality in the data set into 3 grades, and recording the grades as no influence, slight influence and serious influence; after generation, each node on the decision tree marks a branch condition;

step five: and acquiring the relationship between different combination modes of indexes referring to the sound and landscape quality and the influence degree of the sound and landscape quality based on the branch conditions of the decision tree classification model obtained in the fourth step, wherein the relationship is used for monitoring the sound and landscape quality in practice and classifying and identifying the influence degree of the sound and landscape.

2. The method for automatically monitoring the quality of urban sound landscape worthy of protection according to claim 1, characterized in that: in the first step, an acquisition point is arranged at a typical position in a sound landscape scene worth protecting; the acquisition time was 15 seconds and the sampling frequency was 44.1 kHz.

3. The method for automatically monitoring the quality of urban sound landscape worthy of protection according to claim 1, characterized in that: in step two, the types of the noise signals include two types: traffic noise and crowd noise; the magnitude of the sound level of a noise signal is expressed in terms of signal-to-noise ratio, which includes: five cases of-5 dB, 0dB, 5dB, 10dB and 15 dB.

4. The method for automatically monitoring the quality of urban sound landscape worthy of protection according to claim 1, characterized in that: in the second step, the index indicating the quality of the sound landscape comprises: acoustic event spectral center of gravity variance, acoustic event spectral center of gravity variance change, loudness change, sharpness change, loudness fluctuation change, Phi \u1. Phi _1 change amount, Tau _ e change amount, tempo change amount, and roughness change amount; wherein the variance of the spectral centroid of the acoustic events is used to characterize the background sound and acoustic event components of the mixed noise signal and the acoustic landscape signal in Hz²(ii) a The loudness is used for indicating the strength of human ears on the mixed noise signal and the acoustic landscape signal, and the unit is sone; the loudness variation is the loudness variation of the mixed and compressed noise signal relative to the original sound landscape signal, and the unit is sone; the sharpness is used for describing the pitch sense of human ears on the mixed noise signals and the acoustic landscape signals, and reflects the frequency distribution condition of the acoustic signals, and the unit is acum; the sharpness change amount is the sharpness change amount of the mixed and compressed noise signal relative to the original sound landscape signal, and the unit is acum; the loudness fluctuation is used for describing the fluctuation conditions of the mixed noise signal and the acoustic landscape signal, and the unit is dB; the loudness fluctuation variation is the loudness fluctuation variation of the mixed and compressed noise signal relative to the original sound landscape signal, and the unit is dB; phi _1 and Tau _ e are important parameters of an autocorrelation function and are used for describing the repeatability of an acoustic signal on an event, wherein the unit of Phi _1 is dB, and the unit of Tau _ e is ms; the rhythm change amount is the rhythm change amount of the mixed and compressed noise signal relative to the original sound landscape signal, and the unit is BPM; the roughness change is the roughness change of the mixed noise signal relative to the original sound landscape signal, and the unit is asper, and the roughness is used for describing subjective listening feeling of the sound signal caused by periodic time domain fluctuation.

5. The method for automatically monitoring the quality of urban sound landscape worthy of protection according to claim 1, characterized in that: in step three, the evaluation grades of the influence degree of the sound landscape quality comprise: no, slight and severe effects.

6. The method for automatically monitoring the quality of urban sound landscape worthy of protection according to claim 1, characterized in that: in the fourth step, the construction of the decision tree model is based on the CART algorithm, and the attributes are selected and divided by using a 'Gini index' criterion when the CART decision tree is constructed; using max _ depth as a pruning parameter; when determining the depth, setting 1-20 different depth and ratio respectivelySelecting the depth with the best effect as the maximum depth to construct a decision tree model according to the fitting effect of different depths; when the classification effect is determined, the accuracy is used as a reference for evaluating the classification effect, and the expression isWherein TP indicates the number of correct positive examples predicted by the model, TN indicates the number of correct negative examples predicted, and P and N are the total number of positive and negative samples respectively.

Technical Field

The invention belongs to the technical field of sound landscape monitoring, and particularly relates to a protected automatic monitoring method for urban sound landscape quality.

Background

The urban sound environment is an important embodiment of urban quality, and noise indexes such as equivalent continuous sound pressure level LAeq, cumulative percentage sound level LN and the like are used as important evaluation modes of the sound environment for a long time. Kang Jian et al in the article [ Acoustic comfort evaluation in ambient open public spaces ] indicate that the subjective comfort of a person to a sound environment is influenced not only by the sound level size but also by other factors such as the type of sound source, etc. Therefore, compared with the traditional noise evaluation mode, the acoustic landscape evaluation method has the characteristics matched with the subjective feeling of people, and the introduction of the concept of the acoustic landscape has important significance for evaluating the acoustic environment. The quality of the sound landscape is not only affected by noise, but also relates to the retention of original good sound elements, and as the urbanization process advances today, the urban noise problem is continuously exposed, and at the same time, beautiful sound is disappearing and changing. Therefore, protecting the acoustic landscapes with urban characteristics and time characteristics is an urgent problem to be solved, and establishing an effective monitoring method early warning system is a primary task of scientifically evaluating the acoustic landscapes so as to develop preventive protection work.

The monitoring method of the sound landscape worth protecting has the following technical problems and difficulties:

(1) a large body of literature such as o.axelson et al in the article a principal components model of soundscapapeutic states that human subjective acoustic comfort is closely related to the type of sound source. More traditional noise evaluation indexes such as LAeq, cumulative percentage sound level LN and the like evaluate the sound environment from the angle of sound level and time distribution, but cannot carry the information of the sound source, so that the sound landscape quality is measured by only using parameters evaluated based on the sound level. In addition, at present, the evaluation standard of the sound landscape worthy of protection is not clear, and the existing acoustic indexes such as the loudness, the roughness, the sharpness, the fluctuation and other index parameters of the psychological acoustic indexes also lack the characteristic representation of the sound landscape worthy of protection.

(2) The features of the sound landscape worth protecting are often different from each other for different types of sound landscapes worth protecting. When monitoring the quality of a specific sound landscape worth protecting, the monitoring should accord with the original characteristics of the sound landscape, and the monitoring standard can not be used for monitoring other sound landscape quality. This makes it difficult to adapt one or a set of fixed parameter limits to all the monitoring worth protecting the quality of the sound landscape.

Aiming at the defects and difficulties of the sound landscape quality monitoring method worthy of protection, a new sound landscape quality monitoring method is hopefully developed. Recent years have seen research on objective predictors for sound landscapes, including the dynamic spectral centroid index developed by b.yu in the article [ Development of indicators for the Soundscape in the Urban sounding Streets ], which also confirms that psychoacoustic indices have also been shown to be closely related to human subjective perception. However, one parameter cannot describe the complete characteristics of the sound landscape, and the invention selects 13 indexes which show obvious correlation with the sound landscape quality from the commonly used acoustics physical indexes, including sound event spectrum center variance, sound event spectrum center variance change, loudness change, sharpness change, loudness fluctuation change, Phi _1 change, Tau _ e change, rhythm change and roughness change. Based on the basis, the method considers the mode of combining multiple indexes and combines the latest algorithm model, is used for corresponding objective physical indexes and subjective evaluation of a single scene, and has stronger scientificity and credibility.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide a method for automatically monitoring the quality of urban sound landscape, which is worth protecting. According to the invention, under the idea of combining a plurality of physical indexes, the corresponding characteristics of subjective and objective evaluation are combined, a decision tree algorithm is adopted to train the model, and the model can comprise the combination characteristics of indexes representing the sound and landscape quality, so that the functions of monitoring and classifying the sound and landscape quality are achieved. In the practical application process, an automatic sound landscape quality monitoring system can be established on the basis of the method provided by the invention and is used for realizing monitoring, classification and early warning of urban sound landscape quality worthy of protection. The method ensures scientificity and humanization while realizing automatic monitoring and classification, and can solve the problems of large difference between the actual listening experience and the actual listening experience of people, large error of a measuring result and poor real-time performance and representativeness of the obtained monitoring data in the measurement by using the traditional indexes; replace manual monitoring with automatic monitoring, outside effectively solving the problem that the human factor that manual monitoring exists influences the measuring result degree of accuracy, can also facilitate actual monitoring work, save a large amount of manpower resources.

The invention is realized by the following technical scheme:

a method for automatically monitoring the quality of urban sound landscape with value protection comprises the following steps:

the method comprises the following steps: recording and collecting different quality states of the urban sound landscape worth protecting;

step two: converting the sound signals collected in the step one into digital signals to obtain original sound landscape signals, and mixing and compressing the original sound landscape signals and noise signals of different types and different sound levels to obtain a plurality of mixed and compressed noise signals interfered by noise; calculating indexes of all signals indicating the quality of the sound landscape so as to obtain index parameters of each acquisition segment;

taking the original sound landscape signal without the mixed noise as a comparison group, taking the mixed noise signal after the mixed noise as an evaluation group, and carrying out pairing comparison evaluation on the original sound landscape signal without the mixed noise and the mixed noise signal to obtain the evaluation level of the degree of influence on the sound landscape quality in each acquisition segment;

step four, establishing a decision tree classification model based on the data sets in the step two and the step three, and further dividing the step into the following steps;

4-1, reading a data set and preprocessing the data set;

4-2, training a decision tree model, namely inputting a part of data in the data set as training data and the other part of data as test data into the decision tree model for training; the training of the decision tree model is divided into the following processes: firstly, setting a training data set of a first node as D, and calculating a kini index of the existing characteristics to the data set; secondly, selecting the feature with the minimum Keyny coefficient and the corresponding segmentation point as the optimal feature and the optimal segmentation point from all possible features A and all possible segmentation points a of the feature A, generating two sub-nodes from the current node according to the optimal feature and the optimal segmentation point, and distributing the training data set into the two sub-nodes according to the feature; then, recursively calling the two steps for the two child nodes until a stop condition is met; finally, generating a decision tree model;

4-3, classifying the change degree of the sound and landscape quality in the data set into 3 grades, and recording the grades as no influence, slight influence and serious influence; after generation, each node on the decision tree marks a branch condition;

step five: and acquiring the relationship between different combination modes of indexes referring to the sound and landscape quality and the influence degree of the sound and landscape quality based on the branch conditions of the decision tree classification model obtained in the fourth step, wherein the relationship is used for monitoring the sound and landscape quality in practice and classifying and identifying the influence degree of the sound and landscape.

In the technical scheme, in the first step, the acquisition point is arranged at a typical position in the soundscape scene worthy of protection; the acquisition time was 15 seconds and the sampling frequency was 44.1 kHz.

In the above technical solution, in the second step, the types of the noise signals include two types: traffic noise and crowd noise; the magnitude of the sound level of a noise signal is expressed in terms of signal-to-noise ratio, which includes: five cases of-5 dB, 0dB, 5dB, 10dB and 15 dB.

In the above technical solution, in the second step, the index indicating the quality of the sound landscape includes: acoustic event spectrum center of gravity variance, acoustic event spectrum center of gravity variance change, loudness change, sharpness change, loudness fluctuation change, Phi _1 change, Tau _ e change, tempo change, and roughness change; wherein the variance of the spectral centroid of the acoustic events is used to characterize the background sound and acoustic event components of the mixed noise signal and the acoustic landscape signal in Hz²(ii) a The loudness is used for indicating the strength of human ears on the mixed noise signal and the acoustic landscape signal, and the unit is sone; the loudness variation is the loudness variation of the mixed noise signal relative to the original sound landscape signal and is expressed by sone; the sharpness is used for describing the pitch sense of human ears on the mixed noise signals and the acoustic landscape signals, and reflects the frequency distribution condition of the acoustic signals, and the unit is acum; the sharpness change amount is the sharpness change amount of the mixed and compressed noise signal relative to the original sound landscape signal, and the unit is acum; the loudness fluctuation is used for describing the fluctuation conditions of the mixed noise signal and the acoustic landscape signal, and the unit is dB; the loudness fluctuation variation is the loudness fluctuation variation of the mixed and compressed noise signal relative to the original sound landscape signal, and the unit is dB; phi _1 and Tau _ e are important parameters of an autocorrelation function and are used for describing the repeatability of an acoustic signal on an event, wherein the unit of Phi _1 is dB, and the unit of Tau _ e is ms; the rhythm change amount is the rhythm change amount of the mixed and compressed noise signal relative to the original sound landscape signal, and the unit is BPM; the roughness change is the roughness change of the mixed noise signal relative to the original sound landscape signal, and the unit is asper, and the roughness is used for describing subjective listening feeling of the sound signal caused by periodic time domain fluctuation.

In the above technical solution, in the third step, the evaluation level of the degree of influence on the quality of the sound and landscape includes: no, slight and severe effects.

In the technical scheme, in the fourth step, the construction of the decision tree model is based on the CART algorithm, and attributes are selected and divided by using a 'Gini index' criterion when the CART decision tree is constructed; using max _ depth as a pruning parameter; when the depth is determined, 1-20 different depths are respectively set, the fitting effects of the different depths are compared, and the depth with the best effect is selected to be set as the maximum depth to construct a decision tree model; when the classification effect is determined, the accuracy is used as a reference for evaluating the classification effect, and the expression isWherein TP indicates the number of correct positive examples predicted by the model, TN indicates the number of correct negative examples predicted, and P and N are the total number of positive and negative samples respectively.

The invention has the advantages and beneficial effects that:

1) the sound landscape concept is introduced, the combination effect of a plurality of physical indexes is considered, an algorithm model is established, the scientificity and the rigor of the sound landscape quality corresponding to objective physical indexes are improved, and the problems of large difference from actual listening experience of people, large error of measurement results and poor representativeness existing in the traditional sound environment measurement of sound pressure level and frequency spectrum are solved. In the acoustic landscape protection work, an urban acoustic landscape monitoring and early warning system can be established by utilizing a prediction model of acoustic landscape quality, and the quality of the acoustic landscape protected in the city is scientifically evaluated so as to carry out preventive protection work;

2) the automatic detection system can replace manual monitoring, effectively solve the problem that human factors influence the accuracy of the measuring result in the manual monitoring, facilitate the actual monitoring work and save a large amount of human resources.

Drawings

Fig. 1 is a flow chart of the urban sound landscape quality monitoring method worthy of protection of the invention.

For a person skilled in the art, other relevant figures can be obtained from the above figures without inventive effort.

Detailed Description

In order to make the technical solution of the present invention better understood, the technical solution of the present invention is further described below with reference to specific examples.

The invention relates to a decision tree model-based urban sound and landscape quality automatic monitoring method worthy of protection, which comprises the following steps:

the method comprises the following steps: and recording and collecting different quality states of the urban sound landscape worth protecting. The acquisition points are arranged in a scene where the sound landscape worthy of protection is located, the acquisition time is a typical time period of the sound landscape, the scene is typical and representative, and the periphery of the scene is not interfered by noise. The acquisition time is at least 15 seconds; there should be no large reflective surface near the collection point; the used device for collecting the sound signals is a digital recorder or a recording device with the same function, and the sampling frequency is 44.1 kHz.

Step two: converting the sound signals collected in the step one into digital signals to obtain original sound landscape signals, and mixing and compressing the original sound landscape signals and noise signals of different types and different sound levels to obtain a plurality of mixed and compressed noise signals interfered by noise; wherein the noise signals for mixing include traffic sounds and crowd noise; the traffic sound materials are recorded in daytime peak-to-peak periods (9:30-11:30) of the urban main road; the crowd noise material is recorded in the peak passenger flow time period (15: 00-17:00) selected from the urban flourishing commercial street; the instrument and parameter setting used for recording the noise are consistent with the mode of sound and landscape signal acquisition in the step one; the mixing and down operation can be done in DAW software such as Adobe audio. The magnitude of the sound level of a noise signal is expressed in terms of signal-to-noise ratio, which includes: and in five conditions of-5 dB, 0dB, 5dB, 10dB and 15dB, after the original sound landscape signals are mixed with noises of different types and different signal-to-noise ratios, 10 sound landscape signals interfered by the noises are obtained.

After the mixed and compressed noise signal is manufactured, calculating the physical index of the referred sound landscape quality so as to obtain the index parameter of each acquisition segment, wherein the index parameter comprises the following steps:

acoustic event spectral centroid variance: features of background sound and acoustic event components in acoustic landscapes, in Hz²(ii) a Changing the acoustic event spectral center of gravity variance to an acoustic event spectral center of gravity variance change of the mixed noise signal relative to the acoustic landscape signal;

loudness: the intensity of the human ear to the acoustic signal, in sone; changing the loudness into the loudness change quantity of the mixed and compressed noise signal relative to the original sound landscape signal, wherein the unit is sone;

sharpness: the pitch sense of the acoustic signal is in the unit of acum; the sharpness is changed into the sharpness change quantity of the mixed noise signal relative to the original sound landscape signal, and the unit is acum;

loudness fluctuation: counting the difference between the percentage sound levels L10 and L90, reflecting the fluctuation condition of the sound, and the unit is dB; changing the loudness fluctuation into a loudness fluctuation change amount of the mixed noise signal relative to the acoustic landscape signal;

phi _ 1: the first peak in the ACF curve, in dB; phi _1 changes the amount of change of Phi _1 of the mixed and reduced noise signal relative to the original sound landscape signal;

tau _ e: the unit of time delay corresponding to the first peak value in the ACF curve is ms; tau _ e changes to the Tau _ e change amount of the mixed noise signal relative to the acoustic landscape signal;

rhythm: the rhythm speed of the acoustic signal is BPM; the rhythm is changed into the rhythm change quantity of the mixed and reduced noise signal relative to the original sound landscape signal;

roughness change: the subjective audibility of the sound caused by periodic time domain fluctuation is shown in unit of asper; the roughness changes into a roughness change amount of the mixed and reduced noise signal relative to the acoustic landscape signal;

step three: each sound signal segment is subjectively evaluated. Specifically, the acoustic landscape without the interfering sound source is used as a control group, the acoustic landscape with the interfering sound source is used as an evaluation group, and the two are paired and compared. Each sound landscape is played for 15 seconds, and after the playing is finished, the questions to be answered: "what level the reference group soundscape quality belongs to if it is in the original state? "finally obtain the evaluation of the influence degree of the sound landscape quality in each collected segment, including: no, slight and severe effects;

step four: establishing a decision tree classification model based on the data sets in the second step and the third step, wherein the step is further divided into the following steps;

4-1: reading a data set and preprocessing the data set;

4-2: and (3) training the decision tree model, wherein 70% of data in the data set is used as training data, 30% of data is used as test data, and the training data is input into the decision tree model for training. The training of the decision tree model is divided into the following processes: firstly, setting a training data set of a first node as D, and calculating a kini index of the existing characteristics to the data set; secondly, selecting the feature with the minimum Keyny coefficient and the corresponding segmentation point as the optimal feature and the optimal segmentation point from all possible features A and all possible segmentation points a of the feature A, generating two sub-nodes from the current node according to the optimal feature and the optimal segmentation point, and distributing the training data set into the two sub-nodes according to the feature; then, recursively calling the two steps for the two child nodes until a stop condition is met; finally, a decision tree model is generated.

4-3: the degree of change in the quality of the sound landscape in the data set was classified by 3 levels, which were recorded as no effect, slight effect, severe effect. After generation, each node on the decision tree marks a branch condition;

step five: and acquiring the relation between different combination modes of the indicative indexes and the influence degree of the sound and landscape quality based on the branch conditions of the decision tree classification model obtained in the fourth step, and monitoring the sound and landscape quality in practice and classifying and identifying the influence degree of the sound and landscape.

The technical solution of the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

Example 1:

step 1: the selected monitoring object is a park soundscape. The sound recording was performed using a Sony PCM-D50 model digital recorder. The recorder was placed at a height of 1.5 meters above the ground and far from significant noise sources to obtain a relatively realistic and high quality sound signal, with a 15s acquisition time and a sampling frequency of 44.1 kHz.

Step 2: and (2) converting the sound signals collected in the step (1) into digital signals, mixing and compressing the digital signals and noise signals with different types and different sound levels into a plurality of signals, and completing the mixing and compressing operation in the DAW software Adobe Audio.

And (3) calculating and analyzing physical indexes indicating the quality of the sound landscape to obtain index parameters of all signals: all data of acoustic event spectrum center of gravity variance, acoustic event spectrum center of gravity variance change, loudness change, sharpness change, loudness fluctuation change, Phi _1 change, Tau _ e change, tempo change, roughness change, some of which are shown in table 1.

TABLE 1

And step 3: and subjectively evaluating the sound signal of each collected segment. Specifically, the acoustic landscape without the interfering sound source is used as a control group, the acoustic landscape with the interfering sound source is used as an evaluation group, and the two are paired and compared. Each sound landscape is played for 15 seconds, and after the playing is finished, the questions to be answered: "what level the reference group soundscape quality belongs to if it is in the original state? "finally obtain the evaluation of the influence degree of the sound landscape quality in each collected segment, including: no, slight and severe effects. The number of subjects was evaluated subjectively to 30 subjects. Some data are shown in table 2. In the table, the subjective evaluation grade is shown, and the number 1 represents no influence; the number 2 represents a slight effect; the number 3 represents a severe effect.

TABLE 2

And 4, step 4: establishing a decision tree classification model based on the data sets in the second step and the third step, and further dividing the steps into the following steps;

4.1: reading a data set and preprocessing the data set;

4.2: and training a decision tree model. The construction of the decision tree model is based on a CART algorithm, and attributes are selected and divided by using a 'Gini index' criterion when the CART decision tree is constructed; using max _ depth as a pruning parameter; when the depth is determined, 1-20 different depths are respectively set, the fitting effects of the different depths are compared, and the depth with the best effect is selected to be set as the maximum depth to construct a decision tree model; when the classification effect is determined, the accuracy is used as a reference for evaluating the classification effect, and the expression isWherein TP indicates the number of correct positive examples predicted by the model, TN indicates the number of correct negative examples predicted, and P and N are the total number of positive and negative samples respectively. When model training is carried out, 70% of data in the data set is used as training data, 30% of data is used as test data, and the data is input into a decision tree model to train a decision tree. The training of the model is divided into the following processes: firstly, setting a training data set of a first node as D, and calculating a kini index of the existing characteristics to the data set; secondly, selecting the feature with the minimum Keyny coefficient and the corresponding segmentation point as the optimal feature and the optimal segmentation point from all possible features A and all possible segmentation points a of the feature A, generating two sub-nodes from the current node according to the optimal feature and the optimal segmentation point, and distributing the training data set into the two sub-nodes according to the feature; then, recursively calling the two steps for the two child nodes until a stop condition is met; finally, a decision tree model is generated.

4.3: the degree of change in the quality of the sound landscape in the data set was classified by 3 levels, which were recorded as no effect, slight effect, severe effect. After generation, each node on the decision tree indicates a branch condition.

And 5: and acquiring the relation between different combination modes of the indicative indexes and the influence degree of the sound and landscape quality based on the branch conditions of the decision tree classification model obtained in the fourth step, and monitoring the sound and landscape quality in practice and classifying and identifying the influence degree of the sound and landscape. The branch condition can be used as a limit value of the acoustic landscape monitoring index, and the corresponding variable is divided by different critical values and enters the final monitoring model in a plurality of times. Specifically, the relationship between different combinations of these indicative indexes and the degree to which the quality of the sound landscape is affected can be obtained according to the branch conditions. The change degree of the sound landscape quality can be conveniently known through table lookup when the sound landscape quality is actually monitored. The relationship between the combination of the indicative indexes obtained by the decision tree model in this embodiment and the degree of influence on the quality of the sound and landscape is shown in table 3. For this scenario, only the index parameter roughness change plays a dominant role.

TABLE 3

Degree of influence	Roughness modification
		Has no influence on	≤-1.28
Slight influence	-1.155～-0.93
		Severe effects	＞-0.93

When monitoring is carried out, a section of sound and landscape signal segment with the length of 15s is recorded, and the sound and landscape quality at the moment is judged and classified:

the value of calculating the variation of the acoustic landscape quality index value roughness of the acoustic landscape signal segment is-0.84 asper:

and (3) judging the classification of the sound landscape quality as serious influence by combining the relationship between the combination of the indicative indexes and the cruising degree of the sound landscape quality given in the table 3, and taking protective measures on the sound landscape quality.

Example 2:

step 1: the selected monitoring object is Italian style street soundscape. The sound recording was performed using a Sony PCM-D50 model digital recorder. The recorder was placed at a height of 1.5 meters above the ground and far from significant noise sources to obtain a relatively realistic and high quality sound signal, with a 15s acquisition time and a sampling frequency of 44.1 kHz.

Step 2: and (2) converting the sound signals collected in the step (1) into digital signals, mixing and compressing the digital signals and noise signals with different types and different sound levels into a plurality of signals, and completing the mixing and compressing operation in the DAW software Adobe Audio.

And (3) calculating and analyzing physical indexes indicating the quality of the sound landscape to obtain index parameters of all signals: all data of acoustic event spectrum center of gravity variance, acoustic event spectrum center of gravity variance change, loudness change, sharpness change, loudness fluctuation change, Phi _1 change, Tau _ e change, tempo change, roughness change, some of which are shown in table 4.

TABLE 4

Recording number	Variance of center of gravity of sound time spectrum	……	Roughness modification
				1	51.51	……	0.2
2	78.93	……	-0.03
				3	124.27	……	-0.23
4	178.93	……	-0.38
				5	197.2	……	-0.52
6	83.89	……	0.19
				7	100.78	……	-0.06
8	196.06	……	-0.26
				9	228.73	……	-0.44
10	208.49	……	-0.56

And step 3: each sound signal segment is subjectively evaluated. Specifically, the acoustic landscape without the interfering sound source is used as a control group, the acoustic landscape with the interfering sound source is used as an evaluation group, and the two are paired and compared. Each sound landscape is played for 15 seconds, and after the playing is finished, the questions to be answered: "what level the reference group soundscape quality belongs to if it is in the original state? "finally obtain the evaluation of the influence degree of the sound landscape quality in each collected segment, including: no, slight and severe effects. The number of subjects was evaluated subjectively to 30 subjects. Some data are shown in table 5. In the table, the subjective evaluation grade is shown, and the number 1 represents no influence; the number 2 represents a slight effect; the number 3 represents a severe effect.

TABLE 5

And 4, step 4: establishing a decision tree classification model based on the data sets in the second step and the third step, and further dividing the steps into the following steps;

4.1: reading a data set and preprocessing the data set;

4.2: and training a decision tree model. The construction of the decision tree model is based on a CART algorithm, and attributes are selected and divided by using a 'Gini index' criterion when the CART decision tree is constructed; using max _ depth as a pruning parameter; when the depth is determined, 1-20 different depths are respectively set, the fitting effects of the different depths are compared, and the depth with the best effect is selected to be set as the maximum depth to construct a decision tree model; when the classification effect is determined, the accuracy is used as a reference for evaluating the classification effect, and the expression isWherein TP indicates the number of correct positive examples predicted by the model, TN indicates the negative examplesThe exact number of predictions, P and N are the total number of positive and negative samples, respectively. When model training is carried out, 70% of data in the data set is used as training data, 30% of data is used as test data, and the data is input into a decision tree model to train a decision tree. The training of the model is divided into the following processes: firstly, setting a training data set of a first node as D, and calculating a kini index of the existing characteristics to the data set; secondly, selecting the feature with the minimum Keyny coefficient and the corresponding segmentation point as the optimal feature and the optimal segmentation point from all possible features A and all possible segmentation points a of the feature A, generating two sub-nodes from the current node according to the optimal feature and the optimal segmentation point, and distributing the training data set into the two sub-nodes according to the feature; then, recursively calling the two steps for the two child nodes until a stop condition is met; finally, a decision tree model is generated.

4.3: the degree of change in the quality of the sound landscape in the data set was classified by 3 levels, which were recorded as no effect, slight effect, severe effect. After generation, each node on the decision tree indicates a branch condition.

And 5: and acquiring the relation between different combination modes of the indicative indexes and the influence degree of the sound and landscape quality based on the branch conditions of the decision tree classification model obtained in the fourth step, and monitoring the sound and landscape quality in practice and classifying and identifying the influence degree of the sound and landscape. The branch condition can be used as a limit value of the acoustic landscape monitoring index, and the corresponding variable is divided by different critical values and enters the final monitoring model in a plurality of times. Specifically, the relationship between different combinations of these indicative indexes and the degree to which the quality of the sound landscape is affected can be obtained according to the branch conditions. The change degree of the sound landscape quality can be conveniently known through table lookup when the sound landscape quality is actually monitored. The relationship between the combination of the indicative indexes obtained by the decision tree model in this embodiment and the degree of influence on the quality of the sound and landscape is shown in table 6. For this scenario, the index parameter sharpness change and loudness play a dominant role.

TABLE 6

Degree of influence	Sharpness change	Loudness
			Has no influence on	≤-0.165
Slight influence	＞-0.165	≤11.75
			Severe effects	＞-0.165	＞11.75

When monitoring is carried out, a section of sound and landscape signal segment with the length of 15s is recorded, and the sound and landscape quality at the moment is judged and classified:

calculating the sound landscape quality of the sound landscape signal segment, wherein the acutance index value changes, and the loudness values are-0.15 acum and 10.5sone respectively:

and (3) judging the classification of the sound landscape quality as slightly influenced by combining the relationship between the combination of the indicative indexes and the cruising degree of the sound landscape quality given by the table 6, and taking protective measures for the sound landscape quality to relieve the damaged degree of the sound landscape quality.

Although the present invention has been described in connection with the above examples, the present invention is not limited to the above-described embodiments, which are only illustrative and not restrictive, and many modifications may be made by those skilled in the art without departing from the spirit of the present invention within the teaching of the present invention.

The invention has been described in an illustrative manner, and it is to be understood that any simple variations, modifications or other equivalent changes which can be made by one skilled in the art without departing from the spirit of the invention fall within the scope of the invention.