Environmental sound enhancement system

Abstract

To reduce the discomfort caused by noise contained in ambient sounds. [Solution] If it is not possible to select the noise contained in the input ambient sound, the output comfort sound source becomes complicated. Also, if normal noise and steady noise occur simultaneously, only the normal noise with a large peak may be converted, and the steady noise may not be converted. Furthermore, if all the input ambient sound is converted, it may result in an unpleasant sound. Therefore, by dividing the conversion process into two parts (S30~S34, S40~S44), adding a conversion sound determination process (S30, S40), and a chord sound generation process (step S42a), it is possible to handle steady noise while not converting unnecessary sounds. As a result, not only can the unpleasantness of steady noise such as the engine noise of heavy machinery be reduced by the harmony of chord sounds, but even for noises with large peaks, the noise to be converted can be selected, thereby achieving a more effective reduction of unpleasantness.

Description

Technical Field

[0001] The present invention relates to an environmental sound pleasant sound conversion system for converting environmental sounds into pleasant sounds.

Background Art

[0002] Generally, noise is recognized as something unfavorable, and conventionally, various techniques for noise countermeasures are known. For example, in Patent Document 1, noise generated and propagated in a construction machine itself due to the operation of the construction machine is measured using a sound sensor such as a microphone, and when the measured value of the noise is greater than the allowable value, a notification sound is emitted from a speaker inside the driver's cab of the construction machine to notify the operator to that effect. Also, in Patent Document 2, a frequency spectrum of air-conditioning sound is estimated based on the air-conditioning blowing conditions, and a pleasant sound conversion device for selecting a mask sound suitable therefor and outputting it from an audio device is disclosed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] According to the technique described in Patent Document 1, since the operator who has received the notification can be made to perform an operation to suppress the noise below the allowable value, it is considered possible to reduce the influence of construction noise on the neighborhood. Also, according to the technique described in Patent Document 2, since a mask sound is superimposed on the air-conditioning sound, it is considered possible to make the air-conditioning sound less audible.

[0005] However, all of these prior arts are measures taken from the perspective of suppressing noise (preventing loud noises from being produced or making noises less audible), and do not change the unfavorable image of noise, so noise can still be a major source of stress for people. In contrast, if it is possible to improve the image of noise even slightly through some method, it is expected that people will feel less stressed when they hear noise than before, and it may be possible to reduce the discomfort caused by noise included in ambient sounds.

[0006] Therefore, the object of the present invention is to provide a technology that can reduce the discomfort caused by noise contained in ambient sounds. [Means for solving the problem]

[0007] The present invention employs the following solutions to solve the above problems. Note that the following solutions and the terms in parentheses are merely examples, and the present invention is not limited thereto. Furthermore, the present invention can include at least one of the inventive features shown in the following solutions. Moreover, each inventive feature shown in the following solutions can be further subdivided by adding elements that limit the inventive feature, or subdivided by removing those elements.

[0008] Solution 1: The ambient sound enhancement system of this solution comprises an input unit into which noise is input, a conversion unit that converts the noise into a spectrum and converts it into an enhanced sound source of chord tones based on the spectrum, and an output unit that outputs the enhanced sound source.

[0009] According to this solution, noise is converted into a comfortable sound source of chord tones, so that the noise becomes a sonic harmony, and the discomfort caused by noise included in ambient sounds can be further reduced.

[0010] Solution 2: The ambient sound enhancement system of this solution is an ambient sound enhancement system characterized in that, in any of the solutions described above, the conversion unit performs a scale reflection process that converts the sound based on the frequency of the noise into a sound that matches the chord used.

[0011] According to this solution, sounds based on noise frequencies are converted into sounds that match the chord being used, so sounds that do not match the chord tones are not output.

[0012] Solution 3: The ambient sound enhancement system of this solution is characterized in that, in any of the solutions described above, the conversion unit performs a chord tone generation process that generates the chord tone by adding an additional sound to the basic sound based on the frequency of the noise.

[0013] According to this solution, chord tones can be generated simply by adding additional tones to the basic tone.

[0014] Solution 4: The ambient sound enhancement system of this solution is an ambient sound enhancement system characterized in that, in any of the solutions described above, the conversion unit performs chord tone generation processing after performing the scale reflection processing.

[0015] According to this solution, since the chord tone generation process is performed after the scale reflection process is executed, chord tones can be generated efficiently after the scale has been adjusted.

[0016] Solution 5: The ambient sound enhancement system of this solution is characterized in that, in any of the solutions described above, it comprises a determination unit that determines whether the noise input to the input unit is a first noise or a second noise based on the frequency of the noise, the conversion unit converts the first noise into a spectrum and converts it into a first enhancement sound source of a melody sound based on the spectrum, and converts the second noise into a spectrum and converts it into a second enhancement sound source of a chord sound based on the spectrum, and the output unit outputs the first enhancement sound source and the second enhancement sound source.

[0017] According to this solution, noise can be divided into two types of noise and converted into a first comfort-enhancing sound source of melody tones and a second comfort-enhancing sound source of chord tones, thereby further reducing the discomfort caused by noise contained in ambient sounds.

[0018] Solution 6: The ambient sound enhancement system of this solution is an ambient sound enhancement system characterized in that, in any of the solutions described above, the conversion unit converts the first noise or the second noise that exceeds a predetermined noise level into the first comforting sound source or the second comforting sound source.

[0019] According to this solution, only noise exceeding a predetermined noise level is converted into a comfort-enhancing sound source, making it possible to select which noise to convert.

[0020] Solution 7: The ambient sound enhancement system of this solution is an ambient sound enhancement system characterized in that, in any of the solutions described above, the predetermined noise level is different for the first noise and the second noise.

[0021] According to this solution, since the predetermined noise level of the first noise and the predetermined noise level of the second noise can be made different, the noises selected for the first noise and the second noise can be made different.

[0022] Solution 8: In the environmental sound comfort-ifying system of this solution, in any of the above-described solutions, the conversion unit converts the first noise into the first comfort-ifying sound source with a high pitch, and converts the second noise into the second comfort-ifying sound source with a low pitch that is lower in sound than the first comfort-ifying sound source. The environmental sound comfort-ifying system is characterized by this.

[0023] According to this solution, since a first comfort-ifying sound source with a high pitch and a second comfort-ifying sound source with a low pitch are adopted, the roles of the two types of comfort-ifying sound sources are separated, and the discomfort with respect to the noise included in the environmental sound can be further reduced.

[0024] Solution 9: In the environmental sound comfort-ifying system of this solution, in any of the above-described solutions, the conversion unit converts the first noise into the first comfort-ifying sound source with a melody sound, and converts the second noise into the second comfort-ifying sound source with a bass sound. The environmental sound comfort-ifying system is characterized by this.

[0025] According to this solution, since a first comfort-ifying sound source with a melody sound and a second comfort-ifying sound source with a bass sound are adopted, the roles of the two types of comfort-ifying sound sources are separated, and the discomfort with respect to the noise included in the environmental sound can be further reduced.

[0026] Solution 10: In the environmental sound comfort-ifying system of this solution, in any of the above-described solutions, the conversion unit converts the first noise into the first comfort-ifying sound source with a short sound, and converts the second noise into the second comfort-ifying sound source with a long sound that is longer in sound length than the first comfort-ifying sound source. The environmental sound comfort-ifying system is characterized by this.

[0027] According to this solution, since a first comfort-ifying sound source with a short sound and a second comfort-ifying sound source with a long sound are adopted, the roles of the two types of comfort-ifying sound sources are separated, and the discomfort with respect to the noise included in the environmental sound can be further reduced.

Effects of the Invention

[0028] According to the present invention, it is possible to reduce the discomfort caused by noise contained in ambient sounds. [Brief explanation of the drawing]

[0029] [Figure 1] This is a block diagram showing the configuration of the environmental sound enhancement system 10 according to the embodiment. [Figure 2] This figure shows the waveforms of normal noise and steady-state noise. [Figure 3] This is a conceptual diagram showing the range of noise conversion. [Figure 4] This diagram shows an example of selecting which noises to convert. [Figure 5] This diagram shows an overview of the chord tone generation function. [Figure 6] This flowchart shows an example of the processing steps performed by the ambient sound enhancement system 10. [Figure 7] This is a sequence of diagrams showing an example of information input performed by the user through operations on the feature information input unit 13. [Figure 8] This figure shows an example of the application of the environmental sound enhancement system 10 to digital signage. [Modes for carrying out the invention]

[0030] Embodiments of the present invention will be described below with reference to the drawings. Note that the following embodiments are preferred examples of an environmental sound enhancement system, and the present invention is not limited to these examples.

[0031] Figure 1 is a block diagram showing the configuration of the Environmental Sound Enhancement System 10 according to the embodiment. The Environmental Sound Enhancement System 10 is a system that processes environmental sounds, especially noise, to create and output an enhanced sound source (e.g., music) that enhances the sound while making the most of the noise. Furthermore, when construction noise is input, the Environmental Sound Enhancement System 10 follows that sound, converts it into musical instrument sounds, and outputs the enhanced sound source from a speaker. High-frequency noise (e.g., above a certain frequency (250Hz, 500Hz, etc.)) is converted into short musical instrument sounds (e.g., about 1 / 8 beat), and low-frequency noise (e.g., below a certain frequency) is output as long musical instrument sounds (e.g., about 1 / 2 beat). The converted low-frequency sounds are output as chord sounds with the converted sound as the root. The Environmental Sound Enhancement System 10 consists of a computer on which the programs and software necessary for system processing are implemented, and various devices connected to it. The ambient sound enhancement system 10 can be a system constructed using a computer equipped with the following functional components.

[0032] The ambient sound enhancement system 10 can be implemented in digital signage, dedicated PCs (personal computers), dedicated terminals, etc. The ambient sound enhancement system 10 also includes an input unit 11, a judgment unit 12, a feature information input unit 13, a conversion unit 14 (sound enhancement circuit), and an output unit 15.

[0033] The input section 11 is the part that receives noise contained in ambient sound (for example, noise related to construction). The input section 11 is also the part that receives noise contained in ambient sound (first noise, second noise). The input section 11 includes, for example, a sound-collecting microphone. The sound-collecting microphone is a device that collects noise contained in ambient sound outdoors (near a construction site). Examples of sound-collecting microphones include directional microphones, omnidirectional microphones, all-weather microphones, etc.

[0034] The determination unit 12 is the part that determines, based on the noise frequency, whether the noise contained in the ambient sound input to the input unit 11 is normal noise (first noise) or steady-state noise (second noise).

[0035] The feature information input unit 13 is a device (for example, a touch panel) that combines display and input functions. The feature information input unit 13 receives feature information regarding the characteristics of the first sound enhancement source and the second comfort enhancement source in response to operations performed by the user of the ambient sound enhancement system 10.

[0036] The input of feature information may be by direct operation of the feature information input unit 13, or by indirect operation from an external device such as a smartphone. The input of feature information may be for changing only the first sound enhancement source, for changing only the second sound enhancement source, or for changing both the first sound enhancement source and the second sound enhancement source.

[0037] The conversion unit 14 converts noise into a spectrum and then into a comfort-enhancing sound source of chord tones based on that spectrum. Furthermore, the conversion unit 14 converts normal noise into a spectrum and then into a first comfort-enhancing sound source based on that spectrum, and also converts steady-state noise into a spectrum and then into a second comfort-enhancing sound source based on that spectrum. Specifically, the conversion unit 14 converts the normal noise collected by the input unit 11 into a spectrum and then converts that spectrum into MIDI (Musical Instrument Digital Interface) format MIDI data (digital data) for the first comfort-enhancing sound source, which shows the characteristics of each of its components. The conversion to MIDI data is necessary because the signal waveform corresponding to the noise is difficult to process in its original state, as it does not allow for an understanding of the noise's structure.

[0038] Furthermore, the conversion unit 14 converts the MIDI data into a first enhanced sound source and a second enhanced sound source based on the feature information received by the feature information input unit 13. In addition, the conversion unit 14 converts the sound data corresponding to the first enhanced sound source and the second enhanced sound source into an audio signal.

[0039] The output unit 15 is the part that outputs the sound enhancement source. The output unit 15 also outputs the first sound enhancement source and the second sound enhancement source. The output unit 15 includes, for example, a speaker and an amplifier. The speaker can be a directional speaker or an omnidirectional speaker. The output unit 15 outputs the first sound enhancement source and the second sound enhancement source according to the audio signal converted by the conversion unit 14.

[0040] The data and settings handled by each functional unit and circuit of the ambient sound enhancement system 10 are stored in a memory unit (not shown) as needed. The computer constituting the ambient sound enhancement system 10 is a general-purpose computer (for example, a PC, cloud server, smartphone, tablet terminal, etc.) equipped with a CPU, RAM, HDD, various I / Fs, etc., and the computer's CPU functions as each functional unit and circuit by implementing programs etc. on the computer. Alternatively, a computer dedicated to the ambient sound enhancement system 10 may be designed, and physical circuit boards corresponding to each functional unit and circuit may be provided on that computer, either integrally or individually.

[0041] Furthermore, at least one of the input unit 11, determination unit 12, feature information input unit 13, conversion unit 14, and output unit 15 may be connected to a computer via a network or cable, or at least one of these functions may be connected to a second computer separate from the first computer on which the program etc. is implemented, and the first computer and the second computer may be connected via a network or the like.

[0042] Figure 2 shows the waveforms of normal noise and steady-state noise. The vertical axis in the figure represents the noise level (sound pressure level) [dBA], and the horizontal axis represents time [s]. Figure 3 is a conceptual diagram showing the range of noise conversion. In a situation where both normal noise and steady-state noise are present, if only the maximum input sound pressure level is converted into a comfort-enhancing sound source, the steady-state noise, which has a low sound pressure level but is unpleasant to the ear, will not be converted effectively.

[0043] Therefore, in this embodiment, steady-state noise S2, which mainly occurs at low frequencies, is also converted into a comfort-enhancing sound source. That is, in this embodiment, as shown in Figure 3(A), noise across the entire frequency range is not converted together, but as shown in Figure 3(B), the conversion process is branched into two, and steady-state noise S2 of low frequencies and normal noise S1 of high frequencies are converted separately. Furthermore, the frequency width W1 of normal noise S1 can be arbitrarily selected, and the frequency width W2 of steady-state noise S2 can also be arbitrarily selected. Normal noise refers to construction noise that occurs suddenly at demolition sites, etc. Steady-state noise refers to engine noise that occurs steadily due to the use of heavy machinery, etc.

[0044] Figure 4 shows an example of selecting which noises to convert. As shown in Figure 4(A), if all the input noise (noise in range A1) is converted into MIDI data, the number of output sounds becomes too large. Therefore, in this embodiment, as shown in Figure 4(B), both normal noise (noise in range A2) and steady-state noise (noise in range A3) are selected during conversion. This allows for the selection of noises to be converted, thereby narrowing down the number of output sounds.

[0045] Figure 4 shows an image of the converted MIDI data using a user interface similar to that of typical MIDI editing software. The bands of varying lengths shown in the figure correspond to each component of the spectrum. The vertical position of the bands indicates the pitch of each component, and the corresponding sound is represented using piano keys. The length of the bands indicates the duration of each component. The density of the bands may also indicate the sound pressure (intensity) of each component.

[0046] In this embodiment, a first and second enhanced sound source are created by taking into account characteristic information about the musical characteristics input through user operations on such MIDI data. This information about the MIDI data can also be displayed to the user.

[0047] Figure 5 shows an overview of the chord tone generation function. In this embodiment, the added bass tone is used as the root tone and the function is provided to generate chord tones. Specifically, as shown in Figure 5(A), for steady noise (noise in range A3), the sound obtained by converting the steady noise is used as the root tone 20 (basic tone), and the two upper tones 21 and 22 (additional tones) are added to the root tone to generate chord tones.

[0048] The first G (the leftmost in Figure 5(A)) has notes G, B, and D in that order from bottom to top. The next Am has notes A, C, and E in that order from bottom to top. The following G and Am are the same as the first G and Am. The last C has notes C, E, and G in that order from bottom to top. The chord tones are selected from the available chords. The available chords are used to select the chord tones and include multiple chord tones. Note that the available chords may or may not be changeable by the user.

[0049] On the other hand, for normal noise (noise in range A2), the melody tone is a sound obtained by converting the normal noise. The melody tone is selected to match the chord used. Figure 5(B) shows an example of a chord used: the diatonic C major chord (C, Dm, Em, F, G, Am, Bm(♭5)).

[0050] When using a diatonic C major chord, the chord tones will be selected from among the notes of the diatonic C major chord, and the melody tones will be selected from among the notes included in the diatonic C major chord. In particular, when using a diatonic C major chord, only the notes of the white keys of a keyboard instrument will be used (black keys will not be used), which simplifies the selection of notes and simplifies control.

[0051] Figure 6 is a flowchart showing an example of the processing steps performed by the ambient sound enhancement system 10. The following explanation will follow this example.

[0052] Step S10: Input processing of noise contained in ambient sound is performed. In this process, the input unit 11 (sound-collecting microphone, etc.) collects the noise, converts it into an electrical signal, and outputs it. The output electrical signal is transmitted to the determination unit 12 either directly or via a file.

[0053] Step S20: A branching process is performed to distinguish between normal noise and steady-state noise. In this process, the determination unit 12 determines whether the noise input to the input unit 11 is normal noise (first noise) or steady-state noise (second noise) based on the noise frequency.

[0054] The determination unit 12 can determine, for example, that noise is normal noise if its frequency is around 250 to 4 kHz, and that noise is steady-state noise if its frequency is around 63 to 250 Hz. Note that noise at 250 Hz may be determined to be either normal noise or steady-state noise. Furthermore, the boundary frequency between normal noise and steady-state noise can be arbitrarily changed. Additionally, the lower limit of steady-state noise and the upper limit of normal noise can also be arbitrarily changed.

[0055] If the noise is determined to be normal noise, the normal noise conversion flow from steps S30 to S34 is executed. If the noise is determined to be steady-state noise, the steady-state noise conversion flow from steps S40 to S44 is executed.

[0056] [Noise conversion flow for normal noise] Step S30: The conversion sound determination process is executed. In this process, the conversion unit 14 determines whether the normal noise exceeds the first conversion determination line L1 (a predetermined noise level) (whether the noise level of the noise is greater than the numerical value of the line in Figure 2). The conversion unit 14 determines that the normal noise exceeds the first conversion determination line L1 (see Figure 2) and converts it into the first comfort sound source in the subsequent processing.

[0057] Step S31: The process of converting to MIDI data is executed. In this process, the conversion unit 14 converts the electrical signal of the normal noise, which was determined to exceed the first conversion judgment line L1 in step S30, into a frequency spectrum using a Fourier transform or the like, analyzes the frequency spectrum of the normal noise, extracts each component of the spectrum, and converts it into MIDI data for a first pleasing sound source that shows the characteristics of each component of the spectrum (pitch, sound pressure, sound length, etc.). The sound conversion process is executed by the conversion unit 14 using software implemented on the computer. The software may be independently developed and implemented, or existing DAW (Digital Audio Workstation) or other software may be used.

[0058] Step S32: The scale reflection process is executed. In this process, the conversion unit 14 checks whether the selection of the scale (bright feeling, dark feeling, calm feeling, etc.) has been changed by the user's operation. If the selection of the scale has been changed, it executes the scale update process. If the selection of the scale has not been changed, it does not execute the scale update process. When executing the scale update process, the conversion unit 14 updates the scale settings stored in the memory unit with the scale selected by the user's operation.

[0059] In the scale reflection process, the conversion unit 14 reflects the scale settings in the MIDI data for the first optimized sound source. For example, if the user selects "[Dark Feeling 2]" from among several scale options, the conversion unit 14 changes the scale of the music to be created to the scale corresponding to "[Dark Feeling 2]" (for example, D minor). Conversely, if the scale selection has not been changed, the conversion unit 14 maintains the scale of the music to be created at the pre-initialized scale (for example, C major).

[0060] Furthermore, in the scale reflection process, the conversion unit 14 performs a process to convert sounds based on the frequency of normal noise into sounds that match the chord being used. This allows for sound adjustment to match the chord being used. For example, if the chord being used is a diatonic C major chord, and the MIDI data for the first optimized sound source includes the sounds of black keys on a keyboard instrument (sharps or flats), the unit performs a process to change the black key sounds to white key sounds (sounds that do not include sharps or flats). This generates a melody sound that matches the chord being used, resulting in a melody sound that does not sound out of place with the chord sounds.

[0061] Step S33: The timbre reflection process is executed. In this process, the conversion unit 14 checks whether the selection of timbre (type of instrument) has been changed by the user's operation. If the selection of timbre has been changed, it executes the timbre update process. If the selection of timbre has not been changed, it does not execute the timbre update process. When executing the timbre update process, the conversion unit 14 updates the timbre settings stored in the memory unit with the timbre selected by the user's operation.

[0062] In the timbre reflection process, the conversion unit 14 reflects the timbre settings in the MIDI data for the first optimized sound source. For example, if the user selects [Guitar] from among several timbre options, the conversion unit 14 changes the timbre of the music being created to that of a guitar. Conversely, if the timbre selection has not been changed, the conversion unit 14 maintains the timbre of the music being created at the pre-set initial timbre (for example, the violin timbre).

[0063] Step S34: The quantization reflection process is executed. In this process, the conversion unit 14 checks whether the selection of rhythm (fine (fast), normal, coarse (slow), etc.) has been changed by the user's operation. If the selection of rhythm has been changed, the conversion unit 14 executes the rhythm update process. If the selection of rhythm has not been changed, the conversion unit 14 does not execute the rhythm update process. When the rhythm update process is executed, the conversion unit 14 updates the rhythm settings stored in the memory unit with the rhythm selected by the user's operation.

[0064] In the quantization process, the conversion unit 14 applies the rhythm settings to the MIDI data for the first optimized sound source and then performs quantization. For example, if the user selects "[Slightly Fine 1]" from among several rhythm options, the conversion unit 14 changes the rhythm of the music to be created to the rhythm corresponding to "[Slightly Fine 1]" (for example, a rhythm mainly composed of eighth notes). On the other hand, if the rhythm selection has not been changed, the conversion unit 14 maintains the rhythm of the music to be created as the pre-initialized rhythm (for example, a rhythm mainly composed of quarter notes). Then, the conversion unit 14 performs quantization to align the timing of each component sound to match the set rhythm. Then, by executing steps S32 to S34, MIDI data for the first high-quality sound source is generated.

[0065] Note that the processing in steps S32 to S34 can be done in any order. In other words, the above example procedure is merely an example and is not limited to it. For example, the execution of the procedure related to the scale (step S32), the procedure related to the timbre (step S33), and the procedure related to quantization (step S34) is not limited to the above order; for example, the procedure related to the timbre may be executed first, followed by the procedures related to the scale and quantization. In addition, in the above example procedure, information regarding the scale, timbre, and rhythm is input through operations on the feature information input unit 13, but further information regarding musical characteristics (for example, tempo) may also be input. Furthermore, in the above example procedure, initial values ​​are set in advance for the scale, timbre, and rhythm, but instead, for example, an initial value may be set only for the timbre, or the setting of initial values ​​for all items may be left to the user's discretion.

[0066] [Noise conversion flow for steady-state noise] The noise conversion flow for steady-state noise is essentially the same as the noise conversion flow for normal noise, except that the data handled is data for steady-state noise. Therefore, redundant explanations will be omitted as appropriate.

[0067] Step S40: The conversion sound determination process is executed. In this process, the conversion unit 14 determines whether the steady-state noise exceeds the second conversion determination line L2 (a predetermined noise level). The conversion unit 14 determines that the steady-state noise exceeds the second conversion determination line L2 (see Figure 2) and converts it into a second comfort sound source in the subsequent process.

[0068] Here, the first conversion judgment line L1 and the second conversion judgment line L2 are set to different values ​​for normal noise and steady-state noise (see Figure 2). Specifically, the first conversion judgment line L1 is set to a higher value than the second conversion judgment line L2. In addition, the first conversion judgment line L1 can be set to intersect with the waveform of normal noise. As a result, all sounds of normal noise will not be converted. On the other hand, the second conversion judgment line L2 can be set not to intersect with the waveform of steady-state noise and to be positioned below the waveform of steady-state noise. As a result, all sounds of steady-state noise will be converted. However, the second conversion judgment line L2 may also be set to intersect with the waveform of steady-state noise.

[0069] Step S41: The process of converting to MIDI data is executed. In this process, the conversion unit 14 converts the electrical signal of the steady-state noise, which was determined to exceed the second conversion judgment line L2 in step S40, into a frequency spectrum using a Fourier transform or the like, analyzes the frequency spectrum of the steady-state noise, extracts each component of the spectrum, and converts it into MIDI data for a second enhanced sound source that shows the characteristics of each component of the spectrum (pitch, sound pressure, sound length, etc.).

[0070] Step S42: The scale reflection process is executed. In the scale reflection process, the conversion unit 14 reflects the scale settings in the MIDI data for the second optimized sound source. In addition, in the scale reflection process, the conversion unit 14 performs a process to convert the sound based on the frequency of the steady noise into a sound that matches the chord being used. This makes it possible to adjust the sound to match the chord being used. For example, if the chord being used is a diatonic C major chord, and the MIDI data for the second optimized sound source includes the sounds of black keys on a keyboard instrument, the conversion unit 14 performs a process to change the sounds of the black keys to the sounds of white keys. This generates a root note (bass note) that matches the chord being used.

[0071] Step S42a: The chord tone generation process is executed. In the chord tone generation process, the conversion unit 14 generates chord tones by adding additional tones to the basic tone (root tone, bass tone) based on the frequency of the steady noise. Specifically, since the root tone is generated in step S42, the two upper tones are added to that root tone to generate chord tones. After executing the scale reflection process (step S42), the conversion unit 14 executes the chord tone generation process (step S42a).

[0072] Step S43: The timbre reflection process is executed. In the timbre reflection process, the conversion unit 14 reflects the timbre settings in the MIDI data for the second optimized sound source. Step S44: The quantization reflection process is executed. In the quantization reflection process, the conversion unit 14 reflects the rhythm settings in the MIDI data for the second optimized sound source and then performs quantization. Then, by executing steps S42 to S44, MIDI data for the second high-quality sound source is generated. Note that the processing in steps S42 to S44 can be done in any order. However, it is preferable to perform the chord tone generation process (step S42a) after the scale reflection process (step S42).

[0073] Step S50: The process of adding rhythm sounds is executed. In this process, the conversion unit 14 checks whether the addition of rhythm sounds has been changed by the user's operation. If the addition of rhythm sounds has been changed, it executes the process of adding rhythm sounds; however, if the addition of rhythm sounds has not been changed, it does not execute the process of adding rhythm sounds. When the process of adding rhythm sounds is executed, the conversion unit 14 updates the setting for adding rhythm sounds stored in the memory unit with the rhythm sound selected by the user's operation. In addition, in this process, the conversion unit 14 can also check whether OFF for rhythm sounds has been selected by the user's operation. If OFF for rhythm sounds is selected, it executes the process of turning off rhythm sounds; however, if OFF for rhythm sounds has not been selected, it does not execute the process of turning off rhythm sounds. When the process of turning off rhythm sounds is executed, the conversion unit 14 activates the OFF setting for rhythm sounds stored in the memory unit. As a result, the rhythm sounds are not output.

[0074] Furthermore, the conversion unit 14 reflects the setting for adding rhythm sounds in the MIDI data for the first and second optimized sound sources. For example, if the user selects [Drums] from among several options for rhythm sounds, the conversion unit 14 adds drum sounds to the music being created. Conversely, if the selection of rhythm sounds has not been changed, the conversion unit 14 maintains the rhythm sounds of the music being created as the pre-initialized rhythm sounds (e.g., no rhythm sounds, rhythm sounds added by electronic sounds, etc.).

[0075] By performing this process, the conversion unit 14 can create a first enhanced sound source based on normal noise, taking into account the information input by the user of the ambient sound enhancement system 10 through operations on the feature information input unit 13. Furthermore, the conversion unit 14 can create a second enhanced sound source based on steady-state noise, taking into account the information input by the user of the ambient sound enhancement system 10 through operations on the feature information input unit 13.

[0076] Furthermore, the conversion unit 14 can convert normal noise into a first comfort-enhancing sound source with a high frequency (see range A2 in Figure 4, frequency range around C5), and convert steady-state noise into a second comfort-enhancing sound source with a lower frequency (see range A3 in Figure 4, frequency range around C3) than the first comfort-enhancing sound source.

[0077] Furthermore, the conversion unit 14 can convert normal noise into a first comforting sound source of melody sounds (see area A2 in Figure 4, sounds with musical content), and convert steady noise into a second comforting sound source of bass sounds (see area A3 in Figure 4, sounds that form the basis of melody sounds).

[0078] Furthermore, the conversion unit 14 can convert normal noise into a first comforting sound source of short tones (see range A2 in Figure 4, sounds that last for less than a predetermined time), and convert steady noise into a second comforting sound source of long tones (see range A3 in Figure 4, sounds that last for a predetermined time or longer), which are longer in duration than the first comforting sound source.

[0079] Furthermore, the conversion unit 14 can convert normal noise into a first comfort sound source of melody sounds (see area A2 in Figure 5, sounds with musical content), and convert steady noise into a second comfort sound source of chord sounds (see area A3 in Figure 5, sounds synthesized from multiple sounds).

[0080] Step S60: The sound source output process is executed. In this process, the conversion unit 14 converts the MIDI data corresponding to the first and second enhanced sound sources into audio signals and outputs them at a predetermined time (for example, 30ms to 3s) after the noise contained in the ambient sound is input (noise is collected) in step S10. The output audio signal is sent to the output unit 15 directly or via a file. The output unit 15 then immediately outputs the transmitted audio signal. As a result, the first and second enhanced sound sources are output from the output unit 15.

[0081] In the ambient sound enhancement system 10, following the flow described above, a first enhanced sound source and a second enhanced sound source are created based on the noise. After the noise is input (i.e., after the user hears the noise), an audio signal is output at a predetermined time interval, causing the enhanced first and second enhanced sound sources to be output (i.e., the user hears the enhanced first and second enhanced sound sources).

[0082] Incidentally, the reason for deliberately delaying the output of the audio signal (enhanced music) is based on the description in the paper "Experiments and Considerations on the Perception of Delay in Performance Systems with Delay" (by Yu Nishibori et al., Information Processing Society of Japan Research Report, vol.2003, no.127 (2003-MUS-053), pp.37-42, December 21, 2003). This paper shows experimental results indicating that if a delay of 30ms or more is introduced during a musical piece, the sound is perceived as delayed. Based on these experimental results, by deliberately delaying the output of the audio signal and outputting it at a timing after a predetermined amount of time has elapsed since the input of noise contained in the ambient sound, it is possible to make the listener perceive that the first and second enhanced sound sources are delayed from the noise, that is, that the noise and the first and second enhanced sound sources are out of sync (that the noise and the first and second enhanced sound sources are not the same), thereby making the first and second enhanced sound sources easier to hear.

[0083] The above example procedure is merely an example and is not limited thereto. For example, in the above example procedure, the conversion unit 14 delays the output of the audio signal, but instead, the conversion unit 14 may output the audio signal immediately and the output unit 15 may delay the output of the audio signal, or the processing of any of the steps may be delayed so that the timing of the final output of the audio signal is after a predetermined time has elapsed since the noise was collected. In any case, the user can hear the first and second enhanced sound sources, which have been enhanced based on the noise, after a predetermined time has elapsed since the noise was heard. The ambient sound enhancement system 10 may output the first and second enhanced sound sources without waiting for the predetermined time to elapse.

[0084] Figure 7 is a sequence of diagrams showing an example of information input performed by the user through operations on the feature information input unit 13.

[0085] In Figure 7(A): The screen of the feature information input unit 13 displays three items as an ambient sound enhancement menu: for example, timbre selection, scale selection, and rhythm selection. Although not specifically shown in the diagram, the rhythm selection also includes the selection of rhythm sounds. The user can access the screen of the item they touch by touching any of the items. When the ambient sound enhancement system 10 is started, initial settings are applied to each of these three menus, and the output unit 15 outputs a first enhanced sound source M1 in which normal noise is enhanced with the initially set timbre, scale, and rhythm, and a second enhanced sound source M2 in which steady noise is enhanced with the enhancement. Here, we assume that the user touched [Timbre Selection]. The first enhanced sound sources M1 and M3 are melody sounds, and the second enhanced sound sources M2 and M4 are chord sounds. This is the same in Figure 8.

[0086] In Figure 7 (B): When the user touches [Select Tone], the screen of the feature information input unit 13 displays information related to tone selection. Specifically, the initially selected instrument (violin) is displayed at the top of the screen as the current tone. Below that, several instrument options are displayed, and the instrument corresponding to the current tone is surrounded by a thick border. The user can check the instrument options by swiping the screen and change the tone to that instrument by touching any of the other instruments. At this point, the output unit 15 still outputs the first enhanced sound source M1, in which normal noise is enhanced to a pleasant tone based on the initially selected tone (violin), scale, and rhythm, and the second enhanced sound source M2, in which steady noise is enhanced to a pleasant tone. Now, let's assume the user touches [Trumpet].

[0087] In Figure 7 (C): When the user touches [Trumpet], the screen of the feature information input unit 13 displays an indication that the sound selection has been changed. Specifically, at the top of the screen, the previously selected [Trumpet] is displayed as the current sound, and among the multiple instrument options, the previously selected [Trumpet] is displayed surrounded by a thick border. In this way, the user can change the sound selection with intuitive and easy operation. At this point, the output unit 15 outputs the changed sound (trumpet), a first sound-enhancing sound source M3 in which normal noise is enhanced with the initially set scale and rhythm, and a second sound-enhancing sound source M4 in which steady noise is enhanced with the same sound.

[0088] By touching the [Back] button displayed on the screen, users can return to the ambient sound enhancement menu shown in Figure 7(A), from where they can proceed to other items (selection of musical scale, selection of rhythm). The content of the screens related to the other items will not be explained here, but similar to the screen for selecting timbre described above, the screen layout is designed to allow users to change their selections intuitively and easily, even if they do not have specialized knowledge of music.

[0089] In the example shown in Figure 7(A), three selection options (timbre, scale, rhythm) are displayed as part of the ambient sound enhancement menu. However, the system is not limited to these, and further selection options (e.g., tempo) may be displayed. In the examples shown in Figure 7(B) and Figure 7(C), only individual instruments are displayed as options. However, it is also possible to display combinations of multiple instruments as a single option, such as a band (e.g., a combination of guitar, bass, and drums) or a strings ensemble (e.g., a combination of violin, viola, cello, and double bass). When such an option is selected, the noise is transformed into a complex timbre combining multiple instruments, resulting in a more pleasant sound.

[0090] Furthermore, the ambient sound enhancement menu may include a selection of chords to use. By using the chord selection option, users can choose their preferred chords (for example, chords other than diatonic chords, chords other than C major, etc.).

[0091] Furthermore, for the sake of explanation, Figure 7 illustrates an example where only the display for selecting musical characteristics is shown on the feature information input unit 13 screen. However, in addition to this display, other information related to the ambient sound enhancement menu may be displayed on the same screen or on a separate screen, such as displaying the waveforms before and after noise enhancement (at least one waveform such as the waveform of normal noise, the waveform of steady-state noise, the waveform of the first enhanced sound source, and the waveform of the second enhanced sound source). In addition, a questionnaire may be conducted on the feature information input unit 13 screen (questions such as asking about the user's age and gender, and questions about satisfaction with the enhanced sound source), and the data including the questionnaire results may be sent to an external server and saved on the external server.

[0092] Figure 8 shows an example of the application of the ambient sound enhancement system 10 to digital signage. Here, as an example, we show an example of applying the ambient sound enhancement system 10 to a digital signage DS installed at a construction site.

[0093] Figure 8(A) shows a digital signage display DS installed on a temporary fence TF at a construction site, with an output unit 15 installed in close proximity to the digital signage display DS (for example, above the digital signage display DS). The screen of the digital signage display DS displays images of the surrounding scenery and workers, along with greetings to passersby and the name of the construction company. Passersby can access the main menu by touching, for example, the "[Touch here]" button displayed on the screen, and by touching the items displayed in the main menu, they can access various content that can be displayed on the digital signage display DS.

[0094] Furthermore, one of the contents that can be displayed on the digital signage DS is the [Noise Refinement Menu]. The Noise Refinement Menu corresponds to the Ambient Sound Refinement Menu shown in Figure 7, but since the noise included in the ambient sound generated at a construction site is mainly construction noise, it can also be directly referred to as the [Noise Refinement Menu] here. Now, let's assume that a passerby touches the [Touch Here] button and then touches the [Noise Refinement Menu] on the main menu.

[0095] In Figure 8 (B): When a passerby touches the [Noise Refinement Menu], content using the ambient sound refinement system 10 is displayed on the screen of the digital signage DS. Specifically, the right side of the screen (corresponding to the feature information input section 13) displays the same content as the ambient sound refinement menu shown in Figure 7 (A), but since the user here is a passerby, the menu uses more user-friendly language so that any passerby will want to try it without hesitation.

[0096] Furthermore, the output unit 15 outputs a first and second sound source M1 and a second sound source M2, in which noise has been transformed into pleasant sounds according to the initially set timbre, scale, and rhythm. The waveform of the original noise and the waveforms of the first and second sound sources, in which the noise has been transformed into pleasant sounds, are displayed side by side on the left side of the screen. Note that the waveform shapes are for illustrative purposes only. Passersby can freely operate the menu displayed on the right side of the screen and experience transforming noise into music with their own hands.

[0097] Conventional digital signage installed at construction sites displays information such as the details of the construction work to be carried out that day, projected images and photos of the completed work, and weather forecasts. The content is sparse and not something that would make passersby want to stop and look at it.

[0098] In contrast, the digital signage DS, which utilizes the ambient sound enhancement system 10, allows passersby to easily manipulate the noise enhancement menu displayed on the screen, experiencing and enjoying how noise transforms into music by changing the tone, scale, rhythm, etc. By providing such content through the digital signage DS, it is possible to improve people's perception of noise.

[0099] Furthermore, the ambient sound enhancement system 10 may also be applied to digital signage installed in locations other than construction sites. For example, the ambient sound enhancement system 10 may be applied to digital signage installed in airports or train stations, and a first and second enhanced sound source, enhanced based on the noise generated in these locations, may be output as background music. Alternatively, the ambient sound enhancement system 10 may be applied to digital signage installed near highways or railway tracks, and a first and second enhanced sound source, enhanced based on the noise generated in these locations, may be output as new ambient sounds. In addition, the ambient sound enhancement system 10 can be applied to equipment and systems other than digital signage.

[0100] As described above, this embodiment has the following advantages. (1) According to this embodiment, since noise is converted into a comfortable sound source of chord tones, the noise becomes a sonic harmony, and the discomfort caused by noise included in ambient noise can be further reduced. Furthermore, the comfortable sound source converted by this system overlaps with and masks the construction noise, further reducing the discomfort caused by the construction noise. Moreover, by generating chord tones, it becomes closer to music, further reducing the discomfort caused by the construction noise. Construction noise is easily perceived as an unpleasant sound because it has a high noise level and many sudden sounds. Conventional measures such as temporary fencing can reduce the noise level to below the standard value, but they are not very effective in reducing discomfort. However, this system can eliminate such discomfort by using chord tones.

[0101] (2) According to this embodiment, the sound based on the noise frequency is converted into a sound that matches the diatonic chord C major chord (used chord), so that sounds that do not match the chord tone are not output.

[0102] (3) According to this embodiment, chord tones are generated by adding the two upper notes (additional notes) to the root note (basic note), so chord tones can be generated simply.

[0103] (4) According to this embodiment, since the chord tone generation process (Figure 6, step S42a) is performed after the scale reflection process (Figure 6, step S42), chord tones can be generated efficiently after the scale has been adjusted.

[0104] (5) According to this embodiment, the noise contained in ambient sound can be divided into normal noise and steady noise (two types of ambient sound), and these can be converted into a first comforting sound source of melody sound and a second comforting sound source of chord sound. As a result, the discomfort caused by the noise contained in ambient sound can be further reduced by the harmony of the two types of comforting sound sources.

[0105] (6) According to this embodiment, only noise exceeding the first conversion judgment line L1 (a predetermined noise level) or the second conversion judgment line L2 (a predetermined noise level) is converted into a comfort-enhancing sound source, making it possible to select which noise to convert.

[0106] (7) According to this embodiment, the first conversion determination line L1 (a predetermined noise level of the first noise) and the second conversion determination line L2 (a predetermined noise level of the second noise) can be made different, so that the noise to be selected for normal noise and steady-state noise can be made different.

[0107] (8) According to this embodiment, since a first high-frequency comforting sound source and a second low-frequency comforting sound source are employed, the roles of the two types of comforting sound sources are separated, making it possible to further reduce discomfort from noise contained in ambient sounds. In particular, since the first high-frequency comforting sound source is generated intermittently and the second low-frequency comforting sound source is generated continuously, it is possible to improve musicality while maintaining the persistence of the comforting sound source.

[0108] (9) According to this embodiment, since a first comfort-enhancing sound source of melody sound and a second comfort-enhancing sound source of bass sound are employed, the roles of the two types of comfort-enhancing sound sources are separated, making it possible to further reduce the discomfort caused by noise contained in ambient sounds. In particular, since the first comfort-enhancing sound source of melody sound is generated intermittently and the second comfort-enhancing sound source of bass sound is generated continuously, it is possible to improve musicality while maintaining the persistence of the comfort-enhancing sound sources.

[0109] (10) According to this embodiment, since a first comfort-enhancing sound source of short tones and a second comfort-enhancing sound source of long tones are employed, the roles of the two types of comfort-enhancing sound sources are separated, making it possible to further reduce the discomfort caused by noise contained in ambient sounds. In particular, since the first comfort-enhancing sound source of short tones is generated intermittently and the second comfort-enhancing sound source of long tones is generated continuously, it is possible to improve musicality while maintaining the persistence of the comfort-enhancing sound source.

[0110] (11) If it is not possible to select the noise contained in the input ambient sound, the output comfort sound source may become complicated. Also, if normal noise with a large peak and steady noise with a small peak occur simultaneously, it is possible that only the normal noise with a large peak will be converted, and the steady noise will not be converted. Furthermore, if all of the input ambient sound is converted, for example, non-noise sounds may be converted, and the number of converted sounds will increase, creating a complicated sound source that may be unpleasant. Therefore, in this embodiment, the conversion process (flow) is divided into two parts (steps S30 to S34, steps S40 to S44), and a conversion sound determination process (steps S30, S40) and a chord sound generation process (step S42a) are added to address steady noise while not converting unnecessary sounds, thereby solving these problems. As a result, for example, the unpleasantness of steady noise such as the engine noise of heavy machinery can be reduced by the harmony of chord sounds, and even for noise with a large peak, the noise to be converted can be selected, thereby achieving a more effective reduction of unpleasantness.

[0111] [Transformed form] The present invention can be implemented in various ways without being limited to the embodiments described above.

[0112] (1) In the embodiments described above, an example was given in which the first noise is normal noise and the second noise is steady noise, but the first noise may be steady noise and the second noise may be normal noise. Furthermore, the first noise may be a specific noise and the second noise may be a predetermined noise different from the specific noise, not limited to normal noise or steady noise. The ambient sound may be of one type (for example, a specific ambient sound) or of multiple types (for example, a first ambient sound and a second ambient sound). The noise may be of one type (for example, a specific noise) or of multiple types (for example, a first noise and a second noise). The first noise may be a first ambient sound, and the second noise may be a second ambient sound.

[0113] (2) A predetermined noise level does not need to be set. (3) The predetermined noise level may be the same for the first noise and the second noise. (4) A feature information input section is not required.

[0114] (5) In the embodiments described above, the first comfort sound source is high-pitched and the second comfort sound source is low-pitched, but the first comfort sound source may be low-pitched and the second comfort sound source may be high-pitched.

[0115] (6) In the embodiments described above, the first comfort sound source was a melody sound and the second comfort sound source was a bass sound, but the first comfort sound source may be a bass sound and the second comfort sound source may be a melody sound.

[0116] (7) In the embodiments described above, the first comfort sound source is a short tone and the second comfort sound source is a long tone, but the first comfort sound source may be a long tone and the second comfort sound source may be a short tone.

[0117] (8) In the embodiments described above, the first comfort sound source is a melody tone and the second comfort sound source is a chord tone, but the first comfort sound source may be a chord tone and the second comfort sound source may be a melody tone.

[0118] (9) The settings for high / low pitch, melody / bass pitch, short / long note, and melody / chord pitch only need to be adopted at least one combination, and it is not necessary to adopt any combination at all.

[0119] (10) In the above-described embodiment, the output of the audio signal is deliberately delayed, and the audio signal is output at a timing after a predetermined time has elapsed since the noise was collected. However, instead, the audio signal may be output immediately. In this case, the first and second sound enhancement sources will be output at almost the same time that the user hears the noise.

[0120] (11) In the embodiment described above, a touch panel is used for the feature information input unit 13. However, instead, feature information input by the user may be accepted by displaying an operation menu on a display and accepting operations on the operation menu using an input device such as a mouse or keyboard.

[0121] (12) In the embodiments described above, the processing was explained in an example where it was branched for normal noise and steady noise, but it is not necessary to branch the processing. In this case, a specific noise (normal noise only, steady noise only, or noise including both normal noise and steady noise, etc.) is input to the input unit 11, and the processing of the determination unit 12 and step S20 in Figure 6 becomes unnecessary. If the processing is not branched, the two routes in Figure 6 become one route, and only the comfort sound source of the chord tone converted from the specific noise is output from the output unit 15.

[0122] (13) Although the example of converting steady noise into a chord tone-enhancing sound source was explained, steady noise and normal noise may also be converted into a chord tone-enhancing sound source. In this case, for example, this can be achieved by placing a process similar to the chord tone generation process (step S42a) (chord tone generation process for normal noise) between the scale reflection process (step S32) and the timbre reflection process (step S33) in Figure 6.

[0123] (14) The conversion unit 14 does not need to convert the sound based on the noise frequency into a sound that matches the code being used. (15) In the chord tone generation process, the example was given where two notes above the root note were added, but one note above and one note below the root note may also be added, or two notes below the root note may be added. Furthermore, the chords used may not be diatonic chords, and may not be C major chords. (16) Although the example of a chord tone was explained using three notes, a chord tone can also be made up of two notes, or four or more notes. In this case, one of the notes included in the chord tone can be designated as the root note (for example, the fundamental note), and the remaining notes can be designated as additional notes. That is, there can be one additional note or two or more. Furthermore, the note designated as the root note can be changed at will. (17) The chord tone generation process may be performed before the scale reflection process.

[0124] Furthermore, all other examples shown with illustrations in the embodiments are merely preferred examples and can be modified as appropriate when implementing the present invention. [Explanation of Symbols]

[0125] 10. Environmental Sound Enhancement System 11 Input section 12 Judgment section 13. Feature Information Input Section 14 Conversion section 15 Output section M1 First Enhanced Sound Source M2 Second Enhanced Sound Source M3 First Sound Enhancement Source M4 Second Sound Enhancement Source S1 Normal noise S2 Steady-state noise DS Digital Signage

Claims

1. The input section into which noise is input, A conversion unit that converts the aforementioned noise into a spectrum and converts it into a comfortable sound source of chord tones based on the spectrum, An output unit that outputs the aforementioned comfort-enhancing sound source, An environmental sound enhancement system equipped with the following features.

2. In the environmental sound enhancement system described in claim 1, The aforementioned conversion unit is characterized by performing a scale reflection process that converts the sound based on the noise frequency into a sound that matches the chord used, thus creating an environmental sound enhancement system.

3. In the environmental sound enhancement system described in claim 1, The ambient sound enhancement system is characterized in that the conversion unit performs a chord tone generation process that generates the chord tone by adding an additional sound to a basic tone based on the frequency of the noise.

4. In the environmental sound enhancement system described in claim 2, The aforementioned conversion unit is characterized by performing a chord tone generation process after performing a scale reflection process, thereby enhancing the ambient sound quality.

5. In the environmental sound enhancement system described in claim 1, The system includes a determination unit that determines whether the noise input to the input unit is a first noise or a second noise based on the frequency of the noise. The conversion unit converts the first noise into a spectrum and converts it into a first comforting sound source of a melody sound based on the spectrum, and converts the second noise into a spectrum and converts it into a second comforting sound source of a chord sound based on the spectrum. The ambient sound enhancement system is characterized in that the output unit outputs the first comfort-enhancing sound source and the second comfort-enhancing sound source.

6. In the environmental sound enhancement system described in claim 5, The ambient sound enhancement system is characterized in that the conversion unit converts the first noise or the second noise, which exceeds a predetermined noise level, into the first comfort-enhancing sound source or the second comfort-enhancing sound source.

7. In the environmental sound enhancement system according to claim 6, The environmental sound enhancement system is characterized in that the predetermined noise level is different for the first noise and the second noise.

8. In the environmental sound enhancement system described in claim 5, The ambient sound enhancement system is characterized in that the conversion unit converts the first noise into a high-pitched first comforting sound source, and converts the second noise into a low-pitched second comforting sound source that is lower in pitch than the first comforting sound source.

9. In the environmental sound enhancement system described in claim 5, The ambient sound enhancement system is characterized in that the conversion unit converts the first noise into a first comforting sound source of melody sound, and converts the second noise into a second comforting sound source of bass sound.

10. In the environmental sound enhancement system described in claim 5, The ambient sound enhancement system is characterized in that the conversion unit converts the first noise into a short-tone first comforting sound source, and converts the second noise into a long-tone second comforting sound source, which has a longer sound duration than the first comforting sound source.

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