Audio output device

Abstract

To provide a speech output device that has high follow-up properties with respect to change in a travel state of a vehicle.SOLUTION: A speech output device has: a speech reproduction part which outputs a speech with variable volume by reproducing speech data pieces of a first channel and a second channel; and a speech output part which outputs a speech signal obtained by mixing a speech of the first channel and a speech of the second channel. The speech reproduction part performs speech change processing to: output a speech obtained by reproducing a speech data piece corresponding to a first travel state to one of the first channel and the second channel when a travel state of a vehicle is in the first travel state, gradually decrease the volume of the speech output from one channel until the speech is deadened and also output a speech obtained by reproducing a speech data piece corresponding to a second travel state to the other of the first channel and the second channel when the travel state of the vehicle changes from the first travel state to the second travel state.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an audio output device, and more particularly to an audio output device that outputs audio in accordance with the moving speed of a moving object. [Background technology]

[0002] Electric vehicles and electric hybrid vehicles that run on electric motors produce significantly less noise at low speeds than engine vehicles, and so some vehicles have been commercialized equipped with a vehicle approach notification device that emits a sound (hereinafter referred to as a vehicle approach sound) to alert people outside the vehicle that the vehicle is approaching.When the vehicle is traveling slower than a predetermined speed, the vehicle approach notification device changes the tone of the vehicle approach sound depending on the traveling speed.

[0003] As such a vehicle approach notification device, one has been proposed that includes a memory in which data for generating a plurality of different tones is stored in advance, each of which is associated with the vehicle's traveling speed (see, for example, Patent Document 1).

[0004] The vehicle approach notification device first reads from the memory the tone generation data fragments that represent a synthesized sound corresponding to the vehicle's current traveling speed, then converts the concatenated tone generation data fragments that have been sequentially read from the memory into an analog audio signal, and outputs the signal as sound outside the vehicle through a speaker. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-207390 Summary of the Invention [Problem to be solved by the invention]

[0006] In the vehicle approach notification device described above, when the vehicle's traveling speed changes, a new data fragment corresponding to the new traveling speed is read from memory and the data fragment to be reproduced is switched. In this case, it is considered to align the phase of the data fragment so that the timing of the switch does not cause discomfort in the reproduced sound.

[0007] However, in order to align the phases of the data fragments, it is necessary to use periodic sounds that are easy to calculate, such as sine waves, square waves, and sawtooth waves, which makes it difficult to reproduce complex sounds such as engine sounds.

[0008] Furthermore, if you try to align the phases of the data fragments to reduce the sense of incongruity when switching, you need to play back the last sample before starting to play back another data fragment, which causes the problem of poor response to changes in vehicle speed.

[0009] The present invention has been made in view of the above-mentioned problems, and has as its object to provide a sound output device that has high responsiveness to changes in the running state of a vehicle. [Means for solving the problem]

[0010] The audio output device according to the present invention is an audio output device that outputs audio according to a driving state of a vehicle, and includes an audio playback unit that outputs, at adjustable volume, to a first channel an audio that is obtained by reproducing an audio data fragment selected from a plurality of audio data fragments that correspond to each of a plurality of driving states of the vehicle and that are based on a plurality of audio frequencies that change stepwise and are set according to the driving state of the vehicle, and outputs, at adjustable volume, an audio that is obtained by reproducing an audio data fragment selected from the plurality of audio data fragments to a second channel; and an audio output unit that outputs an audio signal that is a mixture of the audio output from the first channel and the audio output from the second channel, wherein, when the driving state of the vehicle is a first driving state, the audio playback unit outputs, to one of the first channel and the second channel, an audio that is obtained by reproducing an audio data fragment that corresponds to the first driving state, When the vehicle's driving state changes from the first driving state to the second driving state, the volume of the audio output from one of the channels is gradually reduced until it is muted, and an audio change process is performed to output an audio fragment corresponding to the second driving state to the other of the first and second channels.

[0011] The audio reproduction method of the present invention is an audio output method executed by an audio output device having: an audio reproduction unit that outputs, at adjustable volume, to a first channel an audio reproduced from an audio data fragment selected from a plurality of audio data fragments, each corresponding to a respective one of a plurality of driving states of the vehicle and based on a plurality of audio frequencies that change gradually according to the driving state of the vehicle, and that outputs, at adjustable volume, an audio reproduced from an audio data fragment selected from the plurality of audio data fragments to a second channel; and an audio output unit that outputs an audio signal that mixes the audio output from the first channel and the audio output from the second channel, wherein the audio output method comprises the steps of: when the driving state of the vehicle is a first driving state, outputting, to one of the first channel and the second channel, an audio reproduced from an audio data fragment corresponding to the first driving state; and when the driving state of the vehicle changes from the first driving state to a second driving state, gradually reducing the volume of the audio output from the one channel until it is muted, and outputting, to the other of the first channel and the second channel, an audio reproduced from an audio data fragment corresponding to the second driving state.

[0012] The program of the present invention is characterized in that it causes an audio output device having an audio playback unit that outputs, at adjustable volume, audio obtained by reproducing audio data fragments selected from a plurality of audio data fragments that each correspond to a plurality of driving states of a vehicle and that are based on a plurality of audio frequencies that change gradually according to the driving state of the vehicle, to a first channel, and that outputs, at adjustable volume, audio obtained by reproducing audio data fragments selected from the plurality of audio data fragments to a second channel, and an audio output unit that outputs an audio signal that mixes the audio output from the first channel and the audio output from the second channel, to execute the following steps: when the driving state of the vehicle is a first driving state, outputting, to one of the first channel and the second channel, audio obtained by reproducing audio data fragments corresponding to the first driving state; and, when the driving state of the vehicle changes from the first driving state to a second driving state, gradually reducing the volume of the audio output from the one channel until it is muted, and outputting, to the other of the first channel and the second channel, audio obtained by reproducing audio data fragments corresponding to the second driving state.

[0013] The recording medium of the present invention causes an audio output device having an audio playback unit that outputs, at adjustable volume, audio reproduced from an audio data fragment selected from a plurality of audio data fragments that each correspond to a plurality of driving states of the vehicle and are based on a plurality of audio frequencies that change stepwise according to the driving state of the vehicle, to a first channel, and that outputs, at adjustable volume, audio reproduced from the audio data fragment selected from the plurality of audio data fragments to a second channel, and an audio output unit that outputs an audio signal that mixes the audio output from the first channel and the audio output from the second channel, to execute the steps of: when the driving state of the vehicle is a first driving state, outputting, to one of the first channel and the second channel, the audio reproduced from the audio data fragment corresponding to the first driving state; and, when the driving state of the vehicle changes from the first driving state to a second driving state, gradually reducing the volume of the audio output from the one channel until it is muted, and outputting, to the other of the first channel and the second channel, the audio reproduced from the audio data fragment corresponding to the second driving state. [Effects of the Invention]

[0014] According to the audio output device of the present invention, in an audio output device that outputs audio according to the driving state of a vehicle, it is possible to improve the ability to follow changes in the driving state. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a block diagram showing the configuration of a vehicle approach notification system; [Figure 2] FIG. 2 is a block diagram showing the internal configuration of the approach notification device. [Figure 3] FIG. 2 is a diagram illustrating an example of a memory map of an audio memory. [Figure 4] 10A and 10B are conceptual diagrams illustrating audio playback on each channel in response to changes in vehicle speed. [Figure 5] 4 is a flowchart showing a processing routine for audio reproduction in the present embodiment. [Figure 6]10 is a flowchart showing a processing routine for audio reproduction in a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0016] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will now be described in detail. In the following description of the embodiments and the accompanying drawings, the same reference numerals are used to designate substantially the same or equivalent parts.

[0017] 1 is a block diagram showing the configuration of a vehicle approach notification system 100 according to the present invention. The vehicle approach notification system 100 is an audio output system that is mounted on a vehicle CA and notifies a driver that the vehicle CA is approaching by outputting audio corresponding to the traveling speed (i.e., vehicle speed) of the vehicle CA.

[0018] The vehicle approach notification system 100 includes a vehicle speed sensor 11 , an approach notification device 12 , and a speaker 13 .

[0019] The vehicle speed sensor 11 detects the traveling speed of the vehicle CA, and supplies the approach notification device 12 with a speed signal VS representing information on the traveling speed.

[0020] The approach notification device 12 generates a vehicle approach sound signal AL having frequency components in the audible band corresponding to the traveling speed represented by the speed signal VS, and supplies the signal to the speaker 13 .

[0021] The speaker 13 is installed, for example, on the front bumper of the vehicle CA, and emits an audible sound based on the vehicle approach sound signal AL as a vehicle approach sound into the space outside the vehicle CA.

[0022] 7 is a block diagram showing the internal configuration of the approach notification device 12. The approach notification device 12 includes a control unit 14, an audio memory 15, an audio playback unit 16, and a mixer 17.

[0023] The control unit 14 receives the speed signal VS from the vehicle speed sensor 11, reads out from the voice memory 15 a voice data fragment corresponding to the traveling speed represented by the speed signal VS, and supplies it to the voice reproduction unit 16. The control unit 14 receives the speed signal VS from the vehicle speed sensor 11 at every interval period SP and checks the traveling speed. In this embodiment, the interval period SP is set to a period sufficiently shorter than one second.

[0024] The voice memory 15 is configured from a storage medium such as a NAND or NOR type flash memory, a nonvolatile semiconductor memory such as a PROM (Programmable ROM), or a magnetic recording hard disk. The voice memory 15 stores voice data fragments AF1 to AF(S) that individually represent a plurality of vehicle approaching sounds, each having different frequency components, in association with each of a plurality of speed zones that divide the range of driving speeds at which the generation of a vehicle approaching sound is required.

[0025] 3 is a diagram showing an example of a memory map of the voice memory 15. The voice memory 15 stores voice data fragments AF1 to AF(S) in association with the respective speed ranges (speed bands) obtained by dividing the range of driving speeds at which approaching vehicle sounds are generated into S (S is an integer of 2 or more). The voice data fragments AF1 to AF(S) are provided so that the frequency changes stepwise.

[0026] For example, the voice memory 15 stores voice data fragment AF1 in voice memory 121, which is associated with a speed range from speed Y1 to speed Y2 (e.g., 0 to 0.5 [km / h]). The voice memory 121 also stores voice data fragment AF2, which is associated with a speed range from speed Y2 to speed Y3 (e.g., 0.5 to 1.0 [km / h]) and corresponds to an approaching vehicle sound with a higher frequency than the voice data fragment AF1. The voice memory 121 also stores synthetic wave data AF3, which is associated with a speed range from speed Y3 to speed Y4 (e.g., 1.0 to 1.5 [km / h]) and corresponds to an approaching vehicle sound with a higher frequency than the voice data fragment AF2.

[0027] Each of the voice data fragments AF1 to AF(S) is set so that the length of the reproduced voice is sufficiently longer than the interval period SP for confirming the vehicle speed. Preferably, the length of the reproduced voice of each of the voice data fragments AF1 to AF(S) is one second or longer.

[0028] 2, the audio playback unit 16 plays back the audio data fragments that the control unit 14 reads from the audio memory 15 based on the traveling speed of the vehicle CA, and outputs them as sound signals. The audio playback unit 16 has the function of simultaneously playing back audio on two channels, channel 0 and channel 1.

[0029] The volume of the audio played back on channel 0 and the volume of the audio played back on channel 1 are both variable. For example, the audio playback unit 16 can perform a process of gradually increasing the playback volume from zero to a predetermined volume (hereinafter referred to as fade-in) and a process of gradually decreasing the playback volume to zero volume (hereinafter referred to as fade-out) for each of channel 0 and channel 1.

[0030] The audio reproduction unit 16 includes a first reproduction unit 18A, a second reproduction unit 18B, a first amplifier 19A, and a second amplifier 19B.

[0031] The first reproduction unit 18A is a first audio reproduction unit that reproduces audio data fragments. The first reproduction unit 18A reproduces audio data fragments on channel 0 (also referred to as CH0).

[0032] The second reproduction unit 18B is a first audio reproduction unit that reproduces audio data fragments. The first reproduction unit 18A reproduces audio data fragments on channel 0 (also referred to as CH0).

[0033] The first amplifier 19A amplifies the sound signal SVA reproduced by the first reproduction unit 18A and supplies it to the mixer 17 as a reproduced sound signal ALA of channel 0.

[0034] The second amplifier 19B amplifies the sound signal SVB reproduced by the second reproduction unit 18B and supplies it to the mixer 17 as a reproduced sound signal ALB of channel 1.

[0035] In this embodiment, when the audio playback unit 16 simultaneously plays back audio data fragments on channel 0 and channel 1, it controls the playback volume of each of the first playback unit 18A and the second playback unit 18B to perform an audio change process (so-called crossfade) in which the audio on one channel is faded in while the audio on the other channel is faded out. For example, if playback of an audio data fragment is started on channel 1 while an audio data fragment is being played on channel 0, the audio on channel 1 is faded in while the audio on channel 0 is faded out. Similarly, if playback of an audio data fragment is started on channel 0 while an audio data fragment is being played on channel 1, the audio on channel 0 is faded in while the audio on channel 1 is faded out.

[0036] The mixer 17 receives the playback sound signal ALA of channel 0 and the playback sound signal ALB of channel 1 output from the audio playback unit 16, mixes them, and supplies the result to the speaker 13 as a vehicle approaching sound signal AL.

[0037] FIG. 4 is an image diagram that schematically shows the reproduction of audio on each channel in response to changes in vehicle speed.

[0038] For example, when vehicle CA starts traveling and its speed reaches the initial speed range Y1-Y2 at which it is necessary to generate a vehicle approaching sound, control unit 14 reads out audio data fragment AF1 from audio memory 15 and supplies it to audio playback unit 16. First playback unit 18A of audio playback unit 16 plays back audio data fragment AF1 on channel 0.

[0039] When the vehicle speed of vehicle CA changes into the speed range Y2-Y3, control unit 14 reads out audio data fragment AF2 from audio memory 15 and supplies it to audio playback unit 16. Second playback unit 18B of audio playback unit 16 starts playing audio data fragment AF2 on channel 1. At this time, first playback unit 18A fades out the audio being played on channel 0, and second playback unit 18B fades in the audio on channel 1. As a result, the audio on both channels is cross-faded (audio change processing) during fade period FP shown in FIG. 4, and approaching sound signal Al output from approaching sound notification device 12 transitions from the audio signal based on audio data fragment AF1 to the audio signal based on audio data fragment AF2. Note that, after the fade-out processing, first playback unit 19A plays back the entire audio data fragment and then stops playback.

[0040] Thereafter, similarly, each time the vehicle speed of vehicle CA changes beyond the speed range corresponding to each of the audio data fragments shown in Fig. 3 (i.e., Y1-Y2, Y2-Y3, Y3-Y4, etc.) at the timing of the vehicle speed confirmation interval period SP, a cross-fade is performed between channel 0 and channel 1, and playback of the audio data fragments is alternately ended and started on each channel. Note that in this embodiment, since the length of the audio played back from each of the audio data fragments AF1 to AF(S) is longer than the vehicle speed confirmation interval period SP as described above, vehicle speed confirmation is performed at least once during playback of each audio data fragment.

[0041] The fade period FP is set to be shorter than the interval period SP for confirming the vehicle speed. The cross-fade starts immediately after the vehicle speed is confirmed and ends within the interval period SP.

[0042] On the other hand, if the vehicle speed of vehicle CA does not change beyond the boundary of the speed range corresponding to each of the audio data fragments at the timing of the vehicle speed confirmation interval period SP, one of the first playback unit 18A and the second playback unit 18B that is currently playing back the audio data fragment continues to repeatedly play back the same audio data fragment.

[0043] Next, the processing operation of the approach notification device 12 of this embodiment for reproducing audio will be described.

[0044] FIG. 5 is a flowchart showing the processing routine for audio reproduction in this embodiment.

[0045] The control unit 14 waits for an interval period SP (STEP 101), and acquires speed information indicating the speed of the vehicle CA based on the speed signal VS of the vehicle speed from the vehicle speed sensor 11 (STEP 102).

[0046] The control unit 14 determines whether the vehicle speed of the vehicle CA is within a speed range that requires the output of an approach warning sound (STEP 103). If it determines that the speed is not within the speed range that requires the output of an approach warning sound (STEP 103: NO), the control unit 14 returns to STEP 101, waits for the interval period SP again, and acquires speed information.

[0047] On the other hand, if it is determined that the speed range requires the output of the approach warning sound (STEP 103: YES), it is determined whether the vehicle speed of vehicle CA has reached the speed range for the first time, i.e., whether the vehicle has entered the speed range from outside the speed range (STEP 104). Here, for example, when the vehicle speed of vehicle CA changes from a speed outside the speed range Y1-Y(S) shown in Figure 3 to a speed within the speed range Y1-Y(S), it is determined that the vehicle has reached the speed range for the first time.

[0048] When it is determined that the vehicle speed has reached the speed range for the first time (STEP 104: YES), the control unit 14 reads out the voice data fragment corresponding to the vehicle speed acquired in STEP 102 from the voice memory 15 and supplies it to the first playback unit 18A, which is responsible for playback on channel 0 (CH0) (STEP 105). The first playback unit 18A plays back the voice data fragment on channel 0 (STEP 106).

[0049] On the other hand, if it is determined that the vehicle has not reached the speed range for the first time (STEP 104: NO), the control unit 14 determines whether the change in speed from the vehicle speed confirmed in the previous vehicle speed confirmation to the vehicle speed acquired in STEP 102 exceeds the boundary of the speed range corresponding to each voice data fragment (i.e., Y1-Y2, Y2-Y3, Y3-Y4, etc. shown in Figure 3) (STEP 107).

[0050] If it is determined that there has been no change in vehicle speed that exceeds the boundary of the speed range (STEP 107: NO), the playback unit of the channel currently playing the audio data fragment (i.e., one of the first playback unit 18A and the second playback unit 18B) again plays the same audio data fragment as the previous audio data fragment (STEP 108).

[0051] On the other hand, if it is determined that there has been a change in vehicle speed that exceeds the boundary of the speed range (STEP 107: YES), the control unit 14 checks whether the channel currently playing the audio data fragment is channel 0 (CH0), i.e., whether playback is being performed by the first playback unit 8A (CH0) or the second playback unit 18B (CH1) (STEP 109).

[0052] If it is determined that the channel being played back is channel 0 (STEP 109: YES), the control unit 14 reads out from the audio memory 15 the audio data fragment corresponding to the vehicle speed acquired in STEP 102, and supplies the read audio data fragment to the second playback unit 18B of the audio playback unit 16 (STEP 110). The second playback unit 18B starts playing audio on channel 1 (STEP 111).

[0053] The audio playback unit 16 controls the volume of playback by the first playback unit 18A to fade out the audio of channel 0, and controls the volume of playback by the second playback unit 18B to fade in the audio of channel 1 (STEP 112).

[0054] The first reproduction unit 18A reproduces one audio data segment to the end while gradually reducing the volume, and then stops the reproduction (STEP 113).

[0055] In STEP 109, if it is determined that the channel being played back is channel 1 (i.e., not channel 0) (STEP 109: NO), the control unit 14 reads out the audio data fragment corresponding to the vehicle speed acquired in STEP 102 from the audio memory 15, and supplies the read audio data fragment to the first playback unit 18A of the audio playback unit 16 (STEP 114). The first playback unit 18A starts playing back audio on channel 0 (STEP 115).

[0056] The audio playback unit 16 controls the volume of playback by the first playback unit 18A to fade out the audio of channel 0, and controls the volume of playback by the second playback unit 18B to fade in the audio of channel 1 (STEP 116).

[0057] The second reproduction unit 18B reproduces one audio data segment to the end while gradually reducing the volume, and then stops the reproduction (STEP 117).

[0058] As described above, the approach notification device 12 of this embodiment selects a plurality of audio data fragments with different frequencies (pitches) according to the vehicle's moving speed, and plays them back while switching the channel between channel 0 and channel 1. When switching channels, the audio output from one channel is faded out, while audio output from the other channel is started and then faded in.

[0059] With this configuration, the frequency (pitch) of the audio data fragment can be changed artificially by switching channels. Also, since the audio can be switched smoothly by cross-fading, the audio data fragment to be played can be switched without causing discomfort to the listener.

[0060] Furthermore, by using cross-fade to switch channels while playing back audio, it is possible to switch the output audio to the audio of another audio data fragment without waiting for the playback of one audio data fragment to finish. Therefore, the approach warning device of this embodiment can improve response to changes in vehicle speed, and enable smooth switching of audio frequencies.

[0061] Furthermore, according to the approach notification device 12 of this embodiment, the playback of audio data fragments in the two channels (playback units) can be switched alternately depending on changes in vehicle speed, so even if the IC constituting the audio playback unit 16 does not have advanced acoustic processing functions, the frequency of the output sound signal can be changed depending on vehicle speed.

[0062] The present invention is not limited to the above embodiment. For example, in the above embodiment, the fade period FP is shorter than the interval period SP, and the cross-fade is executed so as to end within the interval period SP. However, such a limitation on the fade period FP may be eliminated, and the vehicle speed may be stopped from being checked while the cross-fade is being executed.

[0063] 6 is a flowchart showing the processing routine for audio reproduction according to this modified example. The processing up to STEP 108 is the same as the processing routine shown in FIG.

[0064] In STEP 107, when it is determined that the vehicle speed has changed beyond the boundary of the speed range (STEP 107: YES), the control unit 14 stops checking the vehicle speed based on the speed signal VS (STEP 201).

[0065] After STEP 201, the control unit 14 executes the processes of STEPs 108 to 114. After the playback is stopped in STEP 111 or STEP 114, the process returns to STEP 101, and the control unit 14 resumes checking the vehicle speed.

[0066] In the above embodiment, the speed signal VS representing the information on the traveling speed of the vehicle CA is acquired from the vehicle speed sensor 11, and the audio data fragments and channels to be played are switched in accordance with changes in the vehicle speed. However, the present invention is not limited to this, and the audio data fragments and channels may be switched based on a traveling condition other than the traveling speed of the vehicle.

[0067] For example, instead of the vehicle speed sensor 11, the audio data fragment and channel to be reproduced may be switched based on information from an accelerator sensor mounted on the vehicle CA in accordance with the degree of depression of the accelerator.

[0068] In the above embodiment, the audio data fragments AF1 to AF(S) are prepared so that the frequency changes stepwise, and the audio frequency is changed in accordance with changes in the vehicle's running conditions. However, it is also possible to prepare a plurality of audio data fragments that differ in elements other than frequency (for example, audio data fragments that are created so that the sound effect changes stepwise using an equalizer, etc.), and selectively play these fragments in accordance with changes in the vehicle's running conditions.

[0069] In the higher-level embodiment, an approaching vehicle notification device that generates a vehicle approaching sound to notify pedestrians of an approaching vehicle has been described as an example, but the generated sound is not limited to the vehicle approaching sound. In other words, the present invention can be applied to any audio output device that requires a tone that can be changed in real time in response to some input, such as the vehicle's running state. [Explanation of symbols]

[0070] 100 Vehicle Approach Notification System 11 Vehicle speed sensor 12 Approach notification device 13 Speaker 14 Control Unit 15 Audio Memory 16 Audio playback section 17 Mixer 18A 1st playback part 18B 2nd playback part 19A 1st amplifier 19B Second Amplifier

Claims

1. An audio output device that outputs audio according to a vehicle running state, an audio playback unit that outputs, at a volume adjustable level, audio reproduced from an audio data fragment selected from a plurality of audio data fragments based on a plurality of audio frequencies that change stepwise according to the vehicle's running state, to a first channel, and that outputs, at a volume adjustable level, audio reproduced from an audio data fragment selected from the plurality of audio data fragments to a second channel; an audio output unit that outputs an audio signal obtained by mixing the audio output from the first channel and the audio output from the second channel; and the running state of the vehicle is the running speed of the vehicle, each of the plurality of voice data fragments corresponds to a respective one of a plurality of speed zones obtained by dividing a speed range into a plurality of zones within which a voice corresponding to a traveling speed is required to be output; the audio playback unit outputs, when the traveling speed of the vehicle is in a first speed range, audio obtained by playing back an audio data fragment corresponding to the first speed range to one of the first channel and the second channel; When the vehicle's traveling speed changes from the first speed range to the second speed range, an audio output device performs an audio change process to gradually reduce the volume of the audio being output from one of the channels until it is muted, and to output audio that is a reproduced audio data fragment corresponding to the second speed range to the other of the first channel and the second channel.

2. The audio output device according to claim 1, characterized in that, in the audio change process, the audio playback unit gradually reduces the volume of the audio being output from one of the channels until it is muted, and gradually increases the volume of the audio being output from the other channel to a predetermined volume.

3. the audio playback unit performs the audio change process based on a driving state acquired at each predetermined confirmation period, 3. The audio output device according to claim 1, wherein a period during which the audio playback unit performs the audio change process is shorter than the predetermined confirmation period.

4. 4. The audio output device according to claim 3, wherein the length of the audio represented by each of the plurality of audio data fragments is longer than the predetermined confirmation period.

5. a control unit that acquires status information indicating a running status of the vehicle and controls the audio playback unit based on the acquired status information; 5. The audio output device according to claim 1, wherein the control unit stops acquiring the state information while the audio playback unit is performing the audio change process.

6. An audio output method executed by an audio output device having: an audio playback unit that outputs, at adjustable volume, to a first channel an audio reproduced from an audio data fragment selected from a plurality of audio data fragments based on a plurality of audio frequencies each corresponding to a respective one of a plurality of speed bands obtained by dividing a range of a vehicle's traveling speed and each varying in stages according to the traveling speed of the vehicle, and that outputs, at adjustable volume, to a second channel an audio reproduced from an audio data fragment selected from the plurality of audio data fragments; and an audio output unit that outputs an audio signal obtained by mixing the audio output from the first channel and the audio output from the second channel, When the traveling speed of the vehicle is in a first speed range, outputting a sound obtained by reproducing a piece of audio data corresponding to the first speed range to one of the first channel and the second channel; When the traveling speed of the vehicle changes from the first speed zone to a second speed zone, gradually reducing the volume of the audio output from the one channel until it is muted, and outputting audio obtained by reproducing audio data fragments corresponding to the second speed zone to the other of the first channel and the second channel; 10. A sound output method comprising:

7. an audio playback unit that outputs, at adjustable volume, to a first channel an audio signal obtained by playing back an audio data fragment selected from a plurality of audio data fragments based on a plurality of audio frequencies each corresponding to a respective one of a plurality of speed bands obtained by dividing a range of a vehicle's traveling speed and each varying in stages according to the traveling speed of the vehicle, and that outputs, at adjustable volume, to a second channel an audio signal obtained by playing back an audio data fragment selected from the plurality of audio data fragments; and an audio output unit that outputs an audio signal obtained by mixing the audio signal output from the first channel and the audio signal output from the second channel, When the traveling speed of the vehicle is in a first speed range, outputting a sound obtained by reproducing a piece of audio data corresponding to the first speed range to one of the first channel and the second channel; When the traveling speed of the vehicle changes from the first speed zone to a second speed zone, gradually reducing the volume of the audio output from the one channel until it is muted, and outputting audio obtained by reproducing audio data fragments corresponding to the second speed zone to the other of the first channel and the second channel; A program to execute.

8. an audio playback unit that outputs, at adjustable volume, to a first channel an audio signal obtained by playing back an audio data fragment selected from a plurality of audio data fragments based on a plurality of audio frequencies each corresponding to a respective one of a plurality of speed bands that divide a range of a vehicle's traveling speed and each varying in stages according to the traveling state of the vehicle, and that outputs, at adjustable volume, to a second channel an audio signal obtained by playing back an audio data fragment selected from the plurality of audio data fragments; and an audio output unit that outputs an audio signal obtained by mixing the audio signal output from the first channel and the audio signal output from the second channel, When the traveling speed of the vehicle is in a first speed range, outputting a sound obtained by reproducing a piece of audio data corresponding to the first speed range to one of the first channel and the second channel; When the traveling speed of the vehicle changes from the first speed zone to a second speed zone, gradually reducing the volume of the audio output from the one channel until it is muted, and outputting audio obtained by reproducing audio data fragments corresponding to the second speed zone to the other of the first channel and the second channel; A recording medium for recording a program for executing the above.

Images