JP2000125398

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DESCRIPTION JP2000125398
[0001]
The present invention relates to an audio communication system comprising a first system part
having a first speaker unit capable of supplying a first sound information signal of a first sound
signal source; And a second system part having a second speaker unit capable of supplying a
second sound information signal of the two sound signal sources.
[0002]
It is often the passenger's wish to listen to music or speech on the headphones, especially in the
rear range. This is especially important when some of the passengers, for example the rear-range
passengers, want to hear, for example, a little different from the driver and the passenger
through speakers built into the vehicle. At that time, there arises a problem that sound
information coming from a speaker incorporated in the vehicle sometimes interferes with a
passenger who wants to hear another sound signal by a headphone. The sound signal from the
headphone is particularly strongly disturbed by the sound signal from the loudspeakers built into
the vehicle at low frequencies, which are full of energy.
[0003]
European Patent Application Publication No. 0 468 610 discloses a headphone system used for
the active suppression of external noise. This head phone system has two speaker units that are
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in close proximity to the right and left ears. An external microphone is attached to each speaker
unit, and its output signal is inverted by the control unit and supplied to the speaker unit through
the mixing unit. Furthermore, the right and left ear parts of the headphone system are provided
with residual microphones, which are exposed to the sound from the loudspeaker unit, whose
output signal is likewise supplied to the mixing unit. A microphone or an input for another signal
is provided, optionally for the headphone system.
[0004]
DE-A 36 27 002 discloses a headphone system which sends sound information signals to the
user in order to actively compensate for disturbing ambient noise. For this purpose, a reference
microphone is attached to the headphone system, which is outside the headphone and accepts
ambient noise and converts it into an electrical signal. These electrical signals are filtered
through a noise compensated filter that simulates the transfer function between the reference
microphone and the ear, and are superimposed in an inverted manner on the sound information
signal supplied to the loudspeaker in the headphone.
[0005]
German Patent Application Publication No. 37 33 132 describes a heed-phone system which
actively suppresses noise, the function of which is known from German Patent Application
Publication No. 36 27 02 specification. However, the reference microphone is provided in the
headphone. In order to prevent unwanted feedback between the microphone signal and the
loudspeaker signal, the headphone system is provided with at least two noise compensation
filters. Optionally, another reference microphone is provided outside the headphone.
[0006]
The sound signal of, for example, a first loudspeaker unit incorporated in a vehicle, for a specific
listening vehicle within the influence of this first loudspeaker unit and the second loudspeaker
unit. It is a technical problem to provide an audible communication system of the type mentioned
at the outset which can be suppressed so that these listeners can hear the sound signal
information almost unhindered by the second speaker unit. It is the basis of the present
invention.
[0007]
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According to the invention, this problem is provided by a compensation unit which mixes the
sound information signal of the first sound signal source with the sound information signal of the
second sound signal source in antiphase. It is solved by being done.
Thus, the user who is exposed to the sound signal from the first speaker unit and the sound
signal from the second speaker unit has the impression that only the sound signal from the
second speaker unit is heard, and the second speaker unit It can be made not to be disturbed by
the sound signal from.
[0008]
In an audio communication system developed according to claim 2, at least one of the two
speaker units is configured as a headphone unit. In this way, in the motor vehicle, regardless of
the position of the passenger in the rear range of the motor vehicle, the sound signal can be
largely compensated by the first loudspeaker unit, and it is possible to use, for example, any
headphone as the second loudspeaker unit is there.
[0009]
In an audio communication system developed according to claim 3, the compensation unit
comprises a phase and frequency correction stage and an inverting matching amplifier, and the
sound information signal of the second sound signal source comprises the sound information of
the first sound signal source. At the listener's ear, mixing the compensation signal derived from
the signal, the sound signal originating from the first speaker unit is secondarily due to the
compensation signal among the sound signals radiated from the speaker unit It is eliminated by
the component. In this way, simple signal processing in the compensation unit can, for example,
ensure that a person who is trying to open the signal via the headphone is not disturbed by the
signals from the other loudspeaker units.
[0010]
Preferred embodiments of the invention are described below with reference to the accompanying
drawings.
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[0011]
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT The audio communication system
shown in FIG. 1 has a first system portion 1 of conventional construction, which system portion 1
is a conventional vehicle speaker unit 9 supplied with a sound information signal 22. It contains.
This sound information signal 22 is the output signal of the output amplifier 8 to which a
preamplifier 7 with sound control circuitry has previously been connected. The preamplifier 7
and the output amplifier 8 selectably originate from a plurality of sound signal sources 4, 5,
which may for example be formed from an AM / FM tuner, a CD drive, a cassette player or a
telephone or may be television sound. It is used to amplify the sound signal 20. The sound
signals 4, 5 can be selected via the switch 6 in order to prepare the sound signal 20 which is not
amplified.
[0012]
The second system part 2 forms the rear space communication system and comprises a
headphone unit 17, a power amplifier 16 and a preamplifier 14 with a sound control network,
these elements 17, 16 and 14 being the first system It is supplied from a sound signal source 10,
11 which corresponds to the sound signal source 4, 5 of part 1 and can therefore include an AF /
FM tuner, a CD drive etc.
[0013]
The first and second system parts 1, 2 are connected by a compensation unit 3 having an
inverting matching amplifier 19 connected in front of a phase and frequency correction stage 18.
The compensation unit 3 is supplied with the sound signal 22 from the first system part 1 in an
amplified form, which is preferably supplied to the speaker unit 9, so that this sound signal 22
from between the output amplifier 8 and the speaker unit 9. Is taken out. The sound signal 22
supplied to the compensation unit 3 is selected in frequency, subjected to a phase shift and
multiplied by an amplification factor. Alternatively, it is also possible to supply uncompensated
signal 20 or only pre-amplified signal 21 to compensation unit 3, as shown in dashed lines in FIG.
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[0014]
Between the preamplifier 14 and the output amplifier 16 in the second system part 2 there is
connected a mixing unit 15, which is symbolically shown as a two-resistor network in FIG. In the
mixing unit 15, the output signal 25 of the compensation unit 3 is superimposed on the output
signal 23 of the preamplifier 14. The output amplifier 16 and thus the headphone unit 17 to be
connected later are supplied with a signal corresponding to a selectable signal by the switch 13
from one of the groups of the sound signal sources 10, 11, additionally to this signal. A signal in
reverse phase is superimposed on the signal 22 for the loudspeaker 9 of the first system part 1.
[0015]
In the audible communication system of FIG. 2 which is slightly modified relative to the audible
communication system of FIG. 1, these elements are given the same reference as long as they
have the function corresponding to the function of the elements of the audible communication
system of FIG. ing. The audio communication system shown in FIG. 2 is the same as the audio
communication system according to FIG. 1 in that the headphone unit 17 of the system part 2 is
supplied from the same signal source 4, 5 provided in the first system part 1. The difference is
only in For this purpose, the output ends of the sound signal sources 4, 5 in the system part 1 are
additionally connected in parallel to the system part 2 via the connecting wires 12a, 12b. Thus,
the switch 13 in the system part 2 selects an input signal from the same group of sound signal
sources for the preamplifier 14 in the second system part 2 and from this input signal the first
system part 1 The input signal 20 for the pre-amplifier 7 of
[0016]
In FIG. 3, for the audible communication system of FIGS. 1 and 2, the loudspeaker unit 9 of the
first system part 1, the headphone unit 17 of the second system part 2, and the ear 26 of a car
passenger with a headphone unit 17. Is shown schematically. In the interior space of the person,
the loudspeaker unit 9 generates a sound signal A which is attenuated at the passenger's ears 26
covered by the headphone unit 17 to the value xA (0 ≦ x ≦ 1). Ru. The sound signal from the
headphone 17 has a component B due to the sound signal selected for the second system part 2
and a compensation factor y (0 ≦ y ≦ 1) in reverse phase to the sound signal A. And since it is
equal to the superposition of the sound signal component-yA attributable to the first system part
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1, the headphone unit 17 provides the sound signal B-yA + xA to the passenger's ear 26. The
frequency selective phase and the amplification factor are set in the compensation unit 3 so that
at least approximately x ≒ y holds over the entire frequency range at the passenger's ear, so that
the passenger is generally only the desired sound information signal B. Will open.
[0017]
Instead of providing the inverting matching amplifier 19 and the phase and frequency correction
stage 18 in the compensation unit 3 as shown, it is also possible to form the compensation unit
by means of a signal processor, and to this signal processor the input signal 20 of the
preamplifier 7. , The signal 21 between the preamplifier 7 and the output amplifier 8 or the
output signal 22 of the output amplifier 8.
[0018]
Thus, with the system according to the invention as described above on the basis of both
embodiments, the sound signal of the first loudspeaker being considered for the listeners of the
first group is a different sound signal source by the listeners of the second group It is possible to
suppress for unhindered reception of sound information of
When used in a car, rear passengers with headphones should select a suitable so-called open
headphone, and then use external hazard information, another passenger's verbal information
and another effective sound that can not be derived from the speaker's sound signal. , Can be
heard together only from being attenuated from the headphone.
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