JPH07131884A - Car audio system - Google Patents

Abstract

PURPOSE:To flatten the frequency characteristic of reproduced sounds by eliminating low-band confined sounds due to resonance of the peculiar mode. CONSTITUTION:With respect to the acoustic signal of an acoustic signal reproducing device 102, middle-pitched and highpitched sounds are reproduced by speakers 109 and 111 attached in the front of a vehicle, and low-pitched sounds including the first-order natural-frequency of the cab are reproduced by speakers 113 and 115 attached in the center of the vehicle. When speakers 113 and 115 are attached in the node of the first-order natural frequency of a cab inside 14, low-pitched confined sounds are eliminated. Thus, the acoustic pressure frequency characteristic is made flat, and an uncomfortable feeling of listeners is reduced, and the articulation of reproduced sounds is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention can flatten the sound pressure-frequency characteristic of the low frequency band at the head position of the occupant of the vehicle and remove the low range muffled sound to reduce the discomfort of the listener. It relates to a car audio system that can be used.

[0002]

2. Description of the Related Art FIG. 4 is a block diagram showing a configuration of a conventional car audio system. In the figure, an audio signal reproducing device 2 and various speakers are attached to a vehicle 1.
An acoustic signal reproducing device 2 shown by a broken line is composed of a signal source 3, a first amplifier 4 and a second amplifier 5, and includes a tuner,
It is a circuit that amplifies an audio signal output from a signal source 3 such as a CD player or a tape player and outputs the amplified audio signal to the speakers 6 to 9.

A vehicle 1 shown on the left of FIG. 4 is a plan view seen from the upper part of the vehicle body. The first speaker 6 is the dashboard 1
It is attached to the 0 or R side front door 11. The second speaker 7 is also the dashboard 10 or the L-side front door 12
Installed on. The third speaker 8 and the fourth speaker 9 are attached to the rear panel 13. The amplifier 4 amplifies the R channel acoustic signal to produce the speakers 6 and 8
To drive. Similarly, the amplifier 5 amplifies the L channel acoustic signal to drive the speakers 7 and 9.

[0004]

In the car audio system having such a structure, when an acoustic signal is reproduced in the passenger compartment 14, a resonance phenomenon occurs at the natural frequency of the passenger compartment 14. In this case, a peak may occur in the sound pressure frequency characteristic at the passenger's head position of the driver's seat 15, the passenger seat 16, or the rear seat 17, and a low-range muffled sound may be generated. Such low-range muffled sound has been a cause of making the listener uncomfortable and further deteriorating the clarity of the reproduced sound.

FIGS. 5 (a) and 5 (b) are a plan view and a side view showing a standing wave of sound generated in the vehicle 1, respectively. Figure 5
(A) is a four-door sedan type passenger car with a displacement of 2000 cc as vehicle 1 and has a passenger compartment 14 viewed from the ceiling.
3 shows the first-order eigenmode of Dashed line A shown in FIG.
Is the first-order eigenmode section. Further, FIG. 5B shows a third-order eigenmode when the vehicle 1 is viewed from the lateral direction, and a broken line B is a node of the third-order eigenmode. As described above, the first eigenmode node is likely to occur between the driver seat 15 and the passenger seat 16 and the rear seat 17. In particular, the peak of the sound pressure frequency characteristic due to the first or third eigenmode is
It was the cause of muffled sound in the low range.

The present invention has been made in view of the above conventional problems, and flattens the sound pressure frequency characteristic at the head position of the occupant and removes the low range muffled sound to make the listener uncomfortable. The purpose of the present invention is to realize a car audio system that reduces power consumption.

[0007]

According to a first aspect of the present invention, there is provided a high-pass filter for filtering mid-tone and high-tone components exceeding a first-order natural frequency of a vehicle interior among acoustic signals of a signal source, and a signal. Of the source acoustic signal, a low-pass filter that filters low-frequency components including the first-order natural frequency of the passenger compartment, a speaker for mid-to-high frequency reproduction to which the amplified signal of the high-pass filter is input, and an amplified signal of the low-pass filter are A speaker for low-frequency sound reproduction to be input, and the speaker for low-frequency sound reproduction is arranged at a position that becomes a node of the first-order eigenmode in the standing wave in the vehicle interior. is there.

According to a second aspect of the present invention, in the acoustic signal of the signal source, a high-pass filter for filtering middle and high frequency components exceeding the third natural frequency of the passenger compartment, and an acoustic signal of the signal source , A low-pass filter that filters low-frequency components including the third natural frequency of the passenger compartment, a speaker for mid-high range reproduction to which the amplified signal of the high-pass filter is input, and a low-frequency reproduction to which the amplified signal of the low-pass filter is input And a speaker in the vehicle interior side wall behind the front seat or the rear door, the first eigenmode section and the third eigenmode section in a standing wave in the vehicle compartment. It is characterized in that a speaker for low-pitched sound reproduction is arranged at a position where and intersect.

[0009]

According to the invention of claim 1 of the present application having such a feature, when a speaker for low-frequency sound reproduction is installed at a position which becomes a node of the first eigenmode of the vehicle interior generated at a low frequency, Resonance of sound at the primary natural frequency originally generated in the room does not occur. Therefore, the low-range muffled sound near the head of the passenger of the vehicle is eliminated, and the clarity of the reproduced sound from the acoustic signal reproducing device can be improved.

According to the invention of claim 2 of the present application, when a speaker for low-pitched sound reproduction is installed at a position which becomes a node of the first and third eigenmodes in the vehicle compartment, it originally occurs in the vehicle compartment. Resonance of sound at the first and third natural frequencies does not occur. Therefore, the low-range muffled sound near the head of the passenger of the vehicle is eliminated, and the clarity of the reproduced sound from the acoustic signal reproducing device can be further improved.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A car audio system according to a first embodiment of the present invention will be described with reference to FIG. FIG. 1 is a block diagram showing the configuration of the car audio system in the first embodiment. Similar to the conventional example, the vehicle 1 is equipped with the acoustic signal reproducing device 102 including the signal source 103 and various speakers. The R channel acoustic signal output from the signal source 103 is a first high pass filter (hereinafter referred to as HP).
F) 104 and a first low-pass filter (hereinafter L
(Hereinafter referred to as PF) 105. The L channel acoustic signal output from the signal source 103 is the second HPF1.
06 and the second LPF 107. HPF10
Reference numerals 4 and 106 denote filters that pass the acoustic signals in the mid-range and high-pitched frequencies that exceed the first-order natural frequency.
Reference numerals 05 and 107 are filters that pass an acoustic signal in a low-pitched sound region including a first-order natural frequency.

The output of the HPF 104 is the first amplifier 108.
Is amplified by and is given to the first speaker 109. HP
The output of F106 is amplified by the second amplifier 110 and
Of the speaker 111. The output of the LPF 105 is amplified by the third amplifier 112, and the third speaker 1
Given to 13. The output of the LPF 107 is amplified by the fourth amplifier 114 and given to the fourth speaker 115. The speakers 109 and 111 are speakers for medium and high frequencies, and are attached to, for example, the dashboard 10 of the vehicle 1 or the wall surface of the front door.

Next, the speakers 113 and 115 are bass speakers and are attached to the section A of the primary eigenmode of the vehicle interior 14 as shown by the broken line in FIG. Figure 3
As shown in, the nodes A of the first eigenmode are distributed perpendicularly to the floor surface of the vehicle 1. Therefore, the speakers 113, 11
The actual mounting location of 5 may be the backrest of the driver's seat 15 and the passenger seat 16, the floor surface, the side wall or the ceiling.

In the car audio system configured as above, the R channel acoustic signal output from the signal source 103 is given to the HPF 104 and LPF 105, and the L channel acoustic signal is supplied to the HPF 106 and LPF1.
It is given to 07. The mid-high frequency component of the R channel acoustic signal is power-amplified by the amplifier 108, the sound is output from the spice 109, and the low-tone component is power-amplified by the amplifier 112, and the sound is output from the splice 113. Similarly, the middle and high frequency components of the L channel acoustic signal are power-amplified by the amplifier 110, the sound is output from the speaker 111, the low-frequency components are power-amplified by the amplifier 114, and the sound is output from the speaker 115.

In the case of a 2000 cc class four-door sedan type passenger car, the frequency in the first natural mode of the passenger compartment 14 is around 80 Hz. In the example shown in FIG. 1, speakers 113 and 115 for low-frequency reproduction are attached to the inside of the passenger compartment at the lower rear of the driver's seat 15 and the passenger's seat 16 which are nodes A of the primary eigenmode. The speaker reproduces the band below the cutoff frequency of the LPFs 105 and 106. Further, the speakers 109 and 111 for reproducing the middle and high frequencies arranged on the front door reproduce sound in a band higher than the cutoff frequencies of the HPFs 104 and 107.

In the acoustic space shown in FIG. 5, it has been confirmed by numerical analysis (computer simulation) that the resonance of this frequency component disappears when a sound source is installed at the node of the first-order eigenmode. By doing so, such standing waves are eliminated, and the low-range muffled sound at the passenger's head position is eliminated.

It should be noted that the speakers 113 and 115 for low frequency reproduction are provided.
The installation location of is not limited to the backrests of the driver's seat 15 and the passenger's seat 16, and may be any location on the side wall of the vehicle compartment 14 as long as it corresponds to the node A of the first eigenmode.

A car audio system according to the second embodiment of the present invention will be described with reference to FIG. Figure 2
FIG. 6 is a block diagram showing the configuration of a car audio system in a second embodiment. The parts different from the first embodiment are that speakers 113a and 115a for low-pitched sound reproduction are R side vehicle interior side wall 18 and L side vehicle interior side wall 19 respectively. It is installed in. The other parts have the same configuration as in the first embodiment, and therefore, the same reference numerals are given and their description is omitted. H
The PFs 104 and 106 are filters that pass high-frequency acoustic signals that exceed the third-order natural frequency, and the LPFs 105 and 107 are filters that pass low-frequency acoustic signals that include the third-order natural frequency.

The third eigenmode of the passenger compartment 14 shown in FIG. 5B has a natural frequency of around 130 Hz in the case of a 2000 cc 4-door sedan type passenger vehicle.
Here, on the R-side vehicle interior side wall 18, the low-frequency reproduction speaker 113a is arranged at a position where the node A of the first eigenmode and the node B of the third eigenmode shown in FIG. 3 intersect. Similarly, on the L-side vehicle interior side wall 19, the first side shown in FIG.
The low frequency reproduction speaker 115a is arranged at a position P where the node A of the next eigenmode and the node B of the third eigenmode intersect. Then, with these speakers 113a and 115a, the LP
The audio band below the cutoff frequency of F105 and 107 is reproduced. Speakers 109 and 111 for middle and high range reproduction are HPF1
Sounds in a frequency band higher than the cutoff frequencies of 04 and 106 are output.

The LPFs 105 and 107 adjust the reproduction frequency bands of the speakers 113a and 115a, respectively, and the HPFs 104 and 106 adjust the reproduction frequency bands of the speakers 109 and 111 for reproducing mid-high frequencies. As a result, the acoustic signal is reproduced without exciting the first and third eigenmodes in the vehicle interior 14, and the low-range muffled sound in the vehicle interior 14 is significantly improved.

[0021]

As described above, according to the present invention, a speaker for low-pitched sound reproduction is attached to a position which becomes a node of an eigenmode in a standing wave in a vehicle interior, so that the low-frequency sound at a head position of a vehicle occupant is reduced. The sound pressure characteristics in the frequency band can be flattened. Therefore, in the car audio system, it is possible to remove the low-range muffled sound in the vehicle interior space and reduce the discomfort of the listener.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a car audio system according to a first embodiment of the invention.

FIG. 2 is a block diagram showing a configuration of a car audio system according to a second embodiment of the present invention.

FIG. 3 is a diagram showing a first-order eigenmode node, a third-order eigenmode node, and their intersections in a vehicle interior.

FIG. 4 is a block diagram showing a configuration example of a conventional car audio system.

FIG. 5A is a plan view showing a first-order eigenmode in the vehicle interior, and FIG. 5B is a side view showing a third-order eigenmode in the vehicle interior.

[Explanation of symbols]

1 Vehicle 10 Dashboard 11 R Side Front Door 12 L Side Front Door 13 Rear Panel 14 Vehicle Interior Space 15 Driver's Seat 16 Passenger Seat 17 Rear Seat 18 R Side Vehicle Interior Side Wall 19 L Side Vehicle Interior Side Wall 102 Acoustic Signal Playback Device 103 Signal source 104,106 HPF 105,107 LPF 108,110,112,114 Amplifier 109,111,113,115,113a, 115a
Speaker A First-order eigenmode section B Third-order eigenmode section

Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI Technical display area H04R 1/28 310 D 5/02 F

Claims (2)

[Claims] 1. A high-pass filter for filtering mid-tone and high-pitched sound components exceeding a first-order natural frequency of a vehicle interior among the acoustic signals of the signal source; and a first of the vehicle interior of the acoustic signals of the signal source. A low-pass filter that filters low-frequency components including the following natural frequencies, a speaker for middle and high-pitched sound reproduction to which the amplified signal of the high-pass filter is input, and a speaker for low-tone reproduction to which the amplified signal of the low-pass filter is input, A car audio system comprising: a speaker for low-pitched sound reproduction, which is arranged at a position that becomes a node of a first-order eigenmode of a standing wave in a vehicle interior. 2. A high-pass filter for filtering mid-tone and high-pitched sound components exceeding a third-order natural frequency of a vehicle interior among the acoustic signals of the signal source; and a third of the vehicle interior of the acoustic signals of the signal source. A low-pass filter that filters low-frequency components including the following natural frequencies, a speaker for middle and high-pitched sound reproduction to which the amplified signal of the high-pass filter is input, and a speaker for low-tone reproduction to which the amplified signal of the low-pass filter is input, A position on the inner wall of the rear door of the vehicle or on the inner side wall of the vehicle behind the front seat where the node of the first-order eigenmode and the node of the third-order eigenmode of the standing wave in the vehicle interior intersect In the car audio system, the speaker for low-frequency sound reproduction is arranged.