Keywords

1 Introduction

After the effective control of the urban acoustic environment, the pursuit of higher quality acoustic environment and urban development environmental characteristics is an important direction of current soundscape research. The sound ecology in urban space has both spatial and temporal characteristics, and these factors influence social development. The high degree of urban development leads to population concentration, and the annoying sounds produced at different stages are regarded as “noise.” After entering the 21st century, most international environmental policies focus on noise control and reduce noise in related economic activity materials or social science research. Levels do not necessarily improve the quality of life in the city. The high degree of urban development leads to population concentration, and the annoying sounds produced at different stages are regarded as “noise.” After entering the 21st century, most international environmental policies focus on noise control and noise reduction in related economic activity data or social science research. It will not improve the quality of life in the city [1,2,3,4]. This is why the research on urban soundscape and the environment tends to be complicated. In addition to the record of objective measurement, it pays attention to the actual feelings and listening experience of human senses, the sound diversity record between cultures and customs among different countries, and urban environments. The sound is seen as a “resource” that can be used, not a “pollution.” While countries examine the urban development context and future planning, the specific soundscapes can respectively mark the characteristics of a regional community, and more and more soundscape features are not in the homogenized urban scene. In Europe, led by Jian Kang, professor of architecture at the University of Sheffield in the United Kingdom, initiated research and became one of the research topics that the EU values. In North America and East Asia and South Asia, including Australia, Canada, the United States, Japan, China, Hong Kong and Taiwan, considerable attention has been paid to soundscape research. In Europe, the launch of related research, led by Jian Kang, professor of architecture at the University of Sheffield, has become a research topic of importance to EU countries. In North America and East Asia and South Asia, including Australia, Canada, the United States, Japan, China, Hong Kong, and Taiwan, considerable attention has been paid to soundscape research [5]. Leading the research institutes such as the Soundscape of European Cities and Landscapes and the UK Noise futures Network, holds a seminar on the future development of urban acoustic environment in 2009, focusing on solving regional soundscape features of future trends and other issues. Driven by this conference, the city center of Sheffield was classified as a basis for quantitative and qualitative analysis of the soundscape characteristics of public spaces [6]. Waterscapes, bird calls and church bells are the most popular among the public, and the language sound is the main source of discomfort for residents. Relevant research has provided the protection direction of British urban soundscape features. In the urban open space, in addition to effectively controlling the sound source, the common walking sound source is generated by walking on different materials and has an influence on subjective sound perception [7]. There are many good examples for perception of acoustic characteristics in European cities, combined with water feature facilities and noise barrier embedded in the open space of the city, using sound insulation walls to block noise sources and waterscapes mask disturbing background noise. This combination of facilities creates culturally significant connotations such as the Sheffield fountain water and metal noise barriers in the UK, the fountains representing rivers and metals representing the steel industry, and the industrial development and urban planning of Sheffield. Two important historical contexts enhance the enjoyment of residents and tourists in these areas, and rich in human and educational significance. Another example is the soundscape planning of the city of Nauener Platz in Berlin, Germany. By combining space zoning and street furniture design, stone walls are used to protect the park people from the surrounding noise. In addition, the combination of semi-enclosed street furniture can also insolate sound influences [8]. Toshimitsu Musha proposed a study of the subjective taste of sound energy. The research content mainly believes that there are active frequencies of 1/f in nature, and the characteristics of 1/f frequency tend to be positive [9]. One of the concepts of the soundscape is that the sounds in the environment should be the sounds that many people like and accept. In this study, the environmental noise test is used to objectively identify the quality of the environmental sounds and then screen them. How to identify the sound produced in the city as a soundscape is generally a pleasure in listening. Although the sounds produced by the traffic tools are disturbing sounds, the sounds integrated into the city are not all annoying noises. The measurement of the acoustic energy level is very similar to the A-weighted acoustic energy dB (A) in response to the frequency response of the human ear. LAeq and LAmax represent the basic characteristics of average sound energy. The measurement of the physical quantity of environmental acoustic energy mostly uses the sound pressure level of the instrument (or sound pressure level, SPL), and the unit used is decibel (dB), and the decibel indicates the intensity or loudness of the sound. People’s hearing and the environment also correspond to the subjective feelings of the decibel standard. Kang [10] notes the current activities and listeners’ expectations and their perception of audible sounds, and the visual visibility of the sound source play an important role. Therefore, these concerns are the decisions of urban development and historical culture. This highly recognizable sound, in sequence, organizes its acoustic physics characteristics, predictively gives a positive evaluation, and explores its subjective feeling correspondence. Based on the theory of soundscape, this study takes the night market trail system as an example to explore the sound field energy collection and frequency analysis of the acoustic environment in the urban pedestrian street.

The urban soundscape triangle developed by M. Schafer (1978) includes Sound Mark, Foreground sounds, and Keynote. Through the classification of acoustic measurement and soundscape research, the classification of sound field characteristics is carried out, and all collected sounds are decomposed into many elements for analysis, which is the key basis of research work. The term “Sound mark” is derived from the landmark, indicating the source of the unique sound that is connected or thought of, such as the church bell. The keynote highlights the representative or base of a string of sounds. Although the tone does not require conscious recognition, it abstracts or condenses the characteristics of a string of sounds. Foreground sound is a noticeable and conscious signal that is different from the background sound. Therefore, it is often organized into a voice code to transmit a message [11]. The high degree of urban development, the proximity of transportation facilities and the convenience of the main roads are important choices for the gathering and living of modern urban residents. The pedestrian space with distinctive open sound field is selected which are including three types of sound fields, pedestrian walking space, commercial space and open space sound field. The results of this research can measure whether the characteristics of sound energy are obscuration noise, or can be divided and defined in frequency characteristics. It can provide the next stage of soundscape perception clarification and analysis, which will be the main follow-up work of this research.

2 Night Market Sound Measurement

The study is based on the international sightseeing night market around Feng Chia University in Taichung as the research space for the commercial street walking the sound field. Feng Chia University’s night market business district is famous for its diverse snacks and sightseeing night market. In recent years, with the government’s tourism promotion, Feng Chia University’s business district has become an attractive tourist attraction in Taiwan. Although the walking sound field is attractive, the key indicators affecting it need to be clarified. At present, according to the survey results, the soundscape characteristics of the Fen Chia Night Market can be initially classified. Through the sound measurement and recording to study the sound field of the pedestrian space along the street in the commercial circle market, the data will become an important basic data for sound perception. At the current stage of measurement, the sound energy of the night market in Fen Chia Business Circle can provide a basis for the complete sound field distribution. The measurement time is performed on weekdays and weekends and is divided into three time periods. A total of 49 measurement points are initially used, and each measurement point is evaluated by LAeq (dB). The measurement time is 1 min, which gives an objective evaluation of the regional soundscape. The sound energy result will become an important basis for the exploration of soundscape perception in the next stage. The measurement points and sound field distribution of Feng Chia University’s night market business circle are shown in Fig. 1.

Fig. 1.
figure 1

Map space of Feng Chia University night market walking system (left), peak and off-peak sound field studies (middle) and 49 measuring points distribution (right).

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2.1 Measuring Equipment

The environmental noise measurement results with the equivalent average volume LAeq (dB) as the evaluation index and the A-weighted noise intermittently exposed in a certain period of time in the selected position in the sound field are averaged by the energy. The parameter index formula is shown in Eq. 1 below.

$$ L_{Aeq} = 10\,\log \,\frac{1}{T}\int_{t}^{t + T} {\left( {\frac{{P_{t} }}{{P_{0} }}} \right)^{2} dt} $$
(1)

LAeq: A-weighted average energy level dB(A) in period time;

T: measurement time in seconds;

Pt: measure sound pressure in Pa;

P0: reference sound pressure, based on 20μPa;

The study conducted environmental acoustic energy measurements, and the sound energy was measured according to the NIEA P201.96C method. The general conditions of on-site acoustic energy measurement are shown in Table 1. The measurement points and apparatus are located on night mark street. (See in Fig. 2.)

Table 1. List of general conditions of the on-site measurement
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Fig. 2.
figure 2

Photos of Feng Chia Night Market on-site measurement are illustrated

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2.2 Results of Room Acoustic Measurement

On site of walking system space in the Feng Chia Night Market, 49 points were selected for measurements, recording at different fixed times and locations. The sound source of the night market walking space is full of changes. Natural sounds and artificial sounds are the main components and interact with each other. All sound sources in this area can be divided into three categories: (1) Natural sound: wind sound, etc.; (2) Equipment sound: car and music sound etc.; and (3) Vocals: footsteps, play and talk. The average noise level of each measurement point is different according to time periods, which are general broadband noise characteristics without obvious significant sound energy. The distribution of LAeq (dB) measurement points is shown in Fig. 3. The measurement time is divided into 16:00 (Starting time), 21:00 (Rush time), and 1:00 am (closing time). The measurement results are 75 dB (A) on average, and the measurement results of each measurement point are shown in the figure.

Fig. 3.
figure 3

The distribution results of 49 field measurement points in three periods in Feng Chia Night Market walking space.

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3 Computer Simulation

The actual measured sound energy distribution map is analyzed with the software and the distribution curve is drawn. The results can be used to analyze the optimal sound energy of the overall distribution of the sound field. Individual environmental factors are used to validate and hypothesize the model. By implementing the measurement correspondence, the sound pressure level image and the sound field model are further drawn, and the future scene and subjective evaluation benchmarks are predicted computer simulation calculation. The simulation was performed by using the German NoiseAtWork software package that can handle energy parameters of tracing calculation and was used to validate the schematic concept of using the energy distribution. The calculus method performs grid computing and plots the contours of the sound energy distribution. The results of the sound field environment generated by computer simulation are visually and visually presented, and the sound field environment in which it is located can be evaluated under different conditions. The simulation results provide a lot of information, including the location and strength of the sound energy. In some cases, this method has the effect of trend prediction, especially under stable sound sources, such as fixed noise sources. Multiple sound source measurements can be discussed simultaneously. For different sound sources, the measures to reduce sound energy can also be plotted and sorted according to the size of the sound energy results.

3.1 Results of Computer Simulation

As a result of the simulation, Feng Chia Night Market is located in the narrow and long streets of the commercial district. It is close to the commercial downtown and the crossroads. Due to the activity at the early morning noon, the decibels are not high, and there are also steam locomotives passing by. In order to make the decibels high or low, there are many people who travel frequently at night time (21:00). The equivalent average sound energy LAeq (dB) is measured, the average value is about 75 dB (A), and the maximum sound energy can be LAmax about 80 dB (A). The noise energy distribution curve simulated by NoiseAtWork computer software is shown in Fig. 4. Following the discussion, in order to reduce the sound energy impact of the sound field, after placing the building group at the profile of cross street (shown in white volume), the sound energy will accumulate and amplify accordingly, and the average sound energy will be raised to 75 dB (A). As shown in Fig. 5, the sound energy distribution curve can provide judgment basis and trend information.

Fig. 4.
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The computer software simulates the street sound energy distribution

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Fig. 5.
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The computer software simulates the street sound energy the curve distribution after being placed in the building volume.

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4 Discussion

Based on the content and methods, this study mainly collects and analyzes the sound environment based on the soundscape related literature. The main target is the commercial pedestrian street along the city recreation space. This study explores the Feng Chia night market in Taiwanese cities, with urban fashion and characteristic business districts, close to high-density residential areas and a large number of crowds, and linear pedestrian streets create linear characteristics of dynamic and static. Acoustic sound source collection includes store street vocals and surrounding environmental humming, including mobile sound sources and fixed sound sources, and draws characteristic sound energy distribution maps, in order to reinterpret the potential characteristics of the pedestrian streets and urban identity. Some preliminary results are abstracted as followed:

  1. (1.)

    Understand the actual sound energy distribution and changes of the pedestrian street soundscape for the current situation, measure and collect the current state and characteristics of the acoustic environment.

  2. (2.)

    Explore the impact of sound on environmental behavior, a soundscape analysis model was proposed to provide reference for subsequent research.

  3. (3.)

    The research results will provide directions for urban planning as a decision-making possibility for the development of tourism and leisure space in the country.