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TECHNICAL FIELD The present invention has a plurality of (that is, one each on the left and right)
acoustic transducers, and starting from the attachment (reference) position to the external ear
protrusion, only a predetermined amount in the front direction The present invention relates to a
stereo headphone of a type in which an acoustic transducer is movably disposed and a method of
optimizing the disposition of the acoustic transducer.
BACKGROUND OF THE INVENTION Headphones for extra-head localization of auditory events
are corrected free or diffuse fields, or are neutrally compensated with respect to direction Known
(K. Genuit: "Warum Freifeld" Report to the Berlin Radio Exhibition ", 1983; Rundfunktechnische
Mittelungen (Radio Technical Report), Volume 1/1983, pages 17 to 26, German Patent No. 31
1347, Fortschritte der Akustik (Development of sound technology)-DAGA 1987, pages 477-480).
The basis of this known method is to simulate the performance of the human ear for directional
localization, which is well defined to be satisfactory.
That is, the upper part of the body, the torso, the head, and the outer parts of the ears are
considered. They are considered as units in the realization and modification of artificial heads,
directional mixing consoles and headphones. In this area, two main types of development have
been made today in artificial heads. Those types can be classified as free sound field corrected
and diffuse sound field corrected (Brueel & Kjaer catalog: "Head and Trunk Simulator 4128,
German Patent Publication No. 3146706; Rundfunktechnische Mittelungen ( Wireless technical
report), Volume 1/1981, pages 1 to 6. Furthermore, so far, only two directional mixing consoles
based mainly on free sound field transmission in the sound field have been developed (HEADACUSTICS: informationpamphlet and report of the 13th Audio Operators Convention, Munich,
1984, pp. 103-110, AKUTISCHE U. KINO-GERAETE, Inc., Information brochure). Reference will be
made to various aspects of the specific importance of the individual adjustments of the
“artificial head headphone” device (J. B1 auert: Spatial Audition, Postscript, New Developments
and Trends since 1972, S. Hirzel Publishing , 1985, Acustica: 48, 272-274). Here we focus
particularly on simulating the human ear's ability for directional localization, which must be
taken into account in the audio signal transmission method, with ldB accuracy. Deviations in
frequency response greater than ld B make it impossible to avoid intracranial localization of the
auditory event in other ways. The reason is that in the case of headphone playback, the
procedure for assigning auditory events to sound sources lacks the visual cues (information)
required to perform the coupling (G. Plenge: Problem of the Intracranial Localization of Sound
Source in Human Acoustic Perception, Habilitation, TU-Berlin l973, 25 pages or less).
Therefore, it is quite important to compensate the single stereo sound signal with possible head
localization of the artificial head or of the directional console individually before the headphones
and then directionalally (they Are suitable for recording devices) (F. Koenig: DE-A 3922 118).
Apart from this, the measurement method, the design of the measuring device and the results
obtained thereby are as already described in connection with the determination of the
transmission function of the outer ear (see above B1 auert: SpatialAudition, Postscript) .
Voice radiation modification “headphones obtained as a simplified procedure that works more
quickly (eg, allowing conclusions to be made as to frequency-dependent distortion, a figure being
obtained after only a few seconds of measurement time) Are described by F. Koenig (see the
respective specifications of German Patent Publication Nos. 3903246 and 3912582).
For directionally true acoustic emission recording and reproduction, B1auert / Boerger / Lams /
Kuerer / to reduce the annoying side effects of "in-head localization" in the reproduction of
recordings via acoustic emission using headphones. Efforts are being made by Plenge / Wilkens /
Pfleiderer et al. (Descriptive Patent Publication Nos. 223316, 2628053, 1927,401, 2244162,
2545446, and 2557519, respectively. Technik (wireless technology) 6, 7/1984, special edition,
German Patent Publication No. 3112874).
Particular emphasis may be placed on the final process (P. M. Pfleiderer's).
The reason is that, as published in "Processors for External Localization of the Head", when used
in a good approximation for implementation, it provides a localization of auditory events
corresponding to scientific terms. (See above, G Plenge, habilitation publication, 1973,).
This device is a very effective processor, which comprises stereo sound followed by spatial
sound, but does not realize one near the possible sound direction in natural three-dimensional
localization of auditory events (from overhead in-head localization) Divergent).
As already mentioned, the directivity of the outer ear contributes to this (see above B1auert,
Spatial Audition, Postscript).
Many articles, publications and patent applications have emerged regarding effective processors
and their technical realization. They describe in particular the simulation of spatial reflection
patterns. Thus, a wide range of such variably programmable reverberators and echo devices
(including space dimensions, space structure and space design) can now be utilized.
Also, "a new kind of presence filter" (J. B1 auert: Fernseh-und Kino-Technik (television and
cinematography) 1970, 3, 75-78) has been known since 1970, Also, a "model for describing the
characteristics of outer ear transmission" is known. It deals with the correction of differences in
the change in the direction of the sound incident from "horizontal" to "lateral" at the ear, "front"
and in front of the head (K. Genuit: Doctoral thesis, Aachen Science and Technology) University,
1984, pages 81-82).
Finally, it is known that when the headphone's acoustic transducer system is moved forward in
the viewing direction, its aural events can be localized to the front in a more or less exactly
horizontal manner. This is because a specific linear correction is made that is directed while the
pinna are receiving a close distance of sound radiation. Here, an acoustic transducer must be
placed at least about 10 centimeters forward in the viewing direction to achieve the
aforementioned effect. Horizontal forward localization of auditory events is via acoustic radiation
using stereo headphones. This is supported by stereo headphones which are realized at high cost.
This provides a bass and mid / treble acoustic transducer system which is separately modulated
in parallel to the left and right auricles where the sound should be emitted (DE 25 31 322;
Funkschau (radio. Review): 10/1977, 57-58 and 71-72).
A stereo headphone of the type mentioned at the outset is known from US Pat. No. 3,559,978.
This known stereo headphone comprises an acoustic transducer system. The acoustic transducer
system is not mounted directly at the external ear protuberances normally, but is moved forward
in the viewing direction by a predetermined amount so that it is at a distance from the external
ear protuberances around a vertical axis It is pivoted. However, because the distance of forward
movement of the direction of the sound is very small, in order to achieve horizontal forward
localization of the auditory event, unlike in the case of the above acoustic transducer
arrangement, which moves at least 10 cm in the viewing direction Is never enough. The reason is
that in US Pat. No. 3,592,978 there is no discussion as to how to achieve horizontal front
localization of auditory events. As is the case in practice, the in-head upward localization of
normal headphones is maintained for this known stereo headphone. The stereo headphones
produce an unnatural sound that makes them feel loud when listening for a long time.
Another known stereo headphone of the type described at the outset is known from US Pat. No.
3,751,608. This known headphone provides an arrangement of acoustic transducer system
similar to that known by U.S. Pat. No. 3,559,978. That is, it is pivoted in the front direction at a
lateral distance from the external ear process. This known stereo headphone is characterized by
the arrangement of the acoustic transducer system in the frontal direction, which is too small for
the frontal localization of the auditory event. Furthermore, U.S. Pat. No. 3,751,608 discloses a
method for optimizing an acoustic transducer system of the following type. That is, this method
experimentally optimizes the arrangement of the acoustic transducers by moving each of the
acoustic transducers, starting from the reference position of the acoustic transducers attached to
the external ear protuberance to be tested, and thus the front direction It is a method of
optimizing the arrangement of left and right acoustic transducers of stereo headphones, which
localizes auditory events. According to that, it is possible to create an auditory event by, in
particular, experimentally optimizing the change of the arrangement of the acoustic transducer
system on both sides in the frontal direction.
SUMMARY OF THE INVENTION The object in the first aspect of the present invention is of the
type described at the outset, improved to ensure that the forward localization of auditory events
is achieved by simple means. To provide stereo headphones. A further object of the second
aspect of the present invention is to provide a method for optimizing the placement of acoustic
transducers of stereo headphones of the type described above, which allows the placement of
acoustic transducers to be determined quickly and reliably.
The object in the first aspect of the present invention is achieved by the configuration described
in the following aspect regarding stereo headphones. That is, a stereo headphone having one
acoustic transducer for each of the left and right, the acoustic transducer being moved and
disposed by a predetermined amount in the front direction, starting from the mounting reference
position to the external ear protrusion, The acoustic transducers are further movable downward
in the frontal direction, by an amount appropriate to convert the intracranial upper localization
into an auditory event that causes the frontal orientation to be localized substantially beyond the
frontal movement. It is characterized in that it is configured. (Aspect 1)
A preferred embodiment (Aspect 2) of the stereo headphone according to the present invention is
given as follows. The acoustic transducer is three-dimensional, either due to: a) the position of
the auditory event above the head relative to the mounting position of the acoustic transducer on
the external ear process, or b) the position horizontally ahead of the auditory event It is
characterized in that it can be arranged variably. (Aspect 2)
With respect to the method according to the second aspect of the present invention (ie the
subject of the present divisional application), the movement of each acoustic transducer is started
starting from the reference position of the acoustic transducer attached to the external ear
protuberance to be tested. A method of optimizing the arrangement of acoustic transducers
experimentally to localize auditory events in the front direction by optimizing the arrangement of
left and right acoustic transducers of stereo headphones, which is for frontal localization of
auditory events By alternately moving the arrangement of each acoustic transducer alternately
downward and forward by a predetermined step width, in order to optimize the arrangement of
the acoustic transducers of the stereo headphones, for the frontal localization of the auditory
event, Furthermore, there is provided a method of optimizing the placement of an acoustic
transducer of a stereo headphone, characterized in that it is moved downward in excess of the
amount of forward movement. (Aspect 3) (Claim 1)
BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments 4 to 21 of the
present invention are as follows, and are the respective objects of claims 2 to 19. (Aspect 4) The
aspect characterized in that the predetermined step width is smaller than 5 millimeters. (Aspect
5) The acoustic transducer of the stereo headphone for the auditory canal is at least one of
increasing the acoustic radiation efficiency in the external ear process and optimizing the
positioning performance of the acoustic transducer on the external ear process. The aspect
characterized by arrange | positioning diagonally. (Aspect 6) An aspect characterized in that the
iterative determination of the optimum arrangement of the acoustic transducers is performed
separately for the left ear and the right ear to be tested. (Aspect 7) An aspect characterized in
that the determination of the optimal arrangement of the acoustic transducers is performed by a
plurality of stereo audio signals that change during the determination process. (Aspect 8) An
aspect characterized in that the optimum arrangement of the acoustic transducers is determined
by at least four movement procedures to be newly repeated in each case. (Aspect 9) Among the
at least four transfer procedures, one transfer procedure having many of the typical features
(Kennzeichen) of the other is selected to determine the optimal arrangement of the acoustic
transducers. Mode to be (Aspect 10) An aspect characterized by performing a migration
procedure on a plurality of test objects. (Aspect 11) An aspect characterized in that at least eight
volunteers who are healthy with respect to the auditory organ are used to determine the optimal
arrangement of acoustic transducers. (Aspect 12) A method characterized by finding an average
of individual results. (Aspect 13) With regard to the angle of inclination of the acoustic
transducer and the forward and downward movement distance, the optimal arrangement of the
acoustic transducer is determined with millimeter accuracy based on the three-dimensional
spatial position of the stereo headphones attached to the outer ear. An aspect characterized by
(Aspect 14) A normal geometrical (three-dimensional) arrangement of acoustic transducers that
cause an intracranial upward localization of an auditory event larger than 2 to 1 by the ratio of
the upward movement distance and the downward and forward movement distance. The aspect
which selects the geometrical arrangement of the acoustic transducer of the stereo headphone
which performs at least one of optimization and minimization with respect to movement distance
on the basis of a frontal direction of an auditory event on the basis of. (Aspect 15) The
stereophonic sound signal of the sound source is supplied to the acoustic transducer for a frontal
auditory event to generate a multidimensional spatial acoustical auditory event, and the
disposition of the acoustic transducer is aurally in the upper position in the head Selecting a
stereo indirect sound derived from the stereo audio signal of the sound source for an event.
(Aspect 16) In order to expand a multi-dimensional spatial auditory event for in-head upward
localization by multi-channel stereo headphones, the arrangement of acoustic transducers is at
least one of the back and the back opposite to the front direction, the front An aspect
characterized by moving to match an auditory event of direction.
(Aspect 17) Freedom among acoustic transducers to produce an auditory event having in-head
upward localization, frontal orientation and multi-dimensional spatial acoustical properties for at
least one of comparative and measurement purposes of auditory events A method of performing
selectable switching. (Aspect 18) At least one of a headphone cup and a stereo headphone, in
order to reliably place the acoustic transducer of the stereo headphone at its resting position so
as to realize at least one of frontal localization and in-head localization of an auditory event. And
a headphone pad used for centering at least one of the auricle and the front of the auricle, which
is filled with a material capable of applying an elastic stress through sound. (Aspect 19) In order
to form a neutral acoustic auditory event, the transmission range of bass and mid tone, coupling
of the head with at least one of a headphone ear pad and a cup structure, and a reproduction
frequency response of an acoustic transducer The aspect characterized by adjusting by at least
one with correction | amendment. (Aspect 20) In at least one of the upper intermediate
transmission range and the upper transmission range of the acoustic transducer in the stereo
headphone as compared to the distortion that occurs in the occurrence of frontal orientation of
the auditory event that is linear, comb-filtered An aspect characterized by performing correction
of a relatively wide band which causes a neutral state of an acoustic pattern. (Aspect 21) An
aspect characterized in that volume setting is performed for audio signals for setting the volume
of an acoustic transducer whose amplitude can be controlled, by separate multi-channel
The essence of the invention consists of a vectorial partial acoustic "bottom" compensation which
interferes with the in-head upper localization and a directional "forward" additional
compensation. It is applied to produce a) external localization away from the head, or b)
horizontal forward localization (other than recording, eg canning of sounds) of an auditory event.
In other words, in short-range acoustic emissions to be tested, for example, the perception of
directionality as being "horizontally forward" during stereo sound reproduction associated with
the head of an artificial head sound recording Two components of the directionality of sound
incidence, not ensured by the individual directional (directed to) characteristics of the human
anatomic auditory sense (accuracy is ldB) that is specific to the directionality of the incidence of
the light, It is secured by the combination of "downward" and "forward".
In this regard, given the overall neglect of the “down” compensation movement (of the
headphone's acoustic transducer system) in accordance with the present invention, the directivity
characteristics of the individual have the threshold of ldB The same undesirable perception of the
direction of the auditory event results, as indicated when crossed.
That is, the auditory event is perceived as being in the frontal direction, but is located
approximately 45 ° obliquely upward (generally in the head and up). This corresponds to the
characteristic features of the recording and reproduction processes of stereo sounds associated
with known heads).
As a method of optimizing the placement of the headphone's acoustic transducer system of the
present invention, efforts are made to move the headphone's acoustic transducer to minimize the
distance for forward localization. For this purpose, preferably at least one of high band diffuse
sound field corrected stereo headphones and an acoustic transducer of the stereo headphones is
For this process, using only the downward compensation movement of the stereo headphone
acoustic transducer device, a "virtual auditory event" is realized in which the directivity can not
be determined unambiguously (but only the forward direction is emphasized) Thus, it is better to
cancel the localization of the auditory events that occur above the head, which usually occur.
Furthermore, in order to realize an auditory event in the horizontal direction opposite to the
frontal direction, in other words in the backward direction, the left and right channels of the
auditory event of both channels corrected for the forward localization of the auditory event It is
good to replace
Also, if a multichannel acoustic transducer system is used to produce improved spatiality and
spatial sound for each pinna exposed to sound, forward and downward for forward localization of
auditory events In addition to the headphone acoustic transducer system being placed, it is also
advantageous to select the arrangement of the headphone acoustic transducer system behind
and under the outer ear structure, according to aspect 16, opposite to the frontal direction.
In accordance with aspect 15, a total of four acoustic transducers are separately modulated.
Besides this, according to the embodiment 19 or 20, it is advantageous to extend the
reproduction characteristics of the stereo headphone acoustic transducer to a 3 dB acoustic
signal at about 300 Hz with the response of the upper body part and the response of the head. .
This is described in more detail, for example, by BLAUERT and GANUIT. This is particularly
advantageous for the headphone design of the present invention.
It is particularly modified according to the theoretical signal transmission base in its design, ie in
its transmission characteristics (eg in reflection space). This is because the adjustment of the
acoustic pattern (e.g. diffuse sound field type post-emphasis) is performed according to the
configuration of aspect 19 or 20, since it is no longer exactly adhered to if it deviates from the
conventional positioning of the acoustic transducer system. . Here, narrow-band (narrower
bandwidth) distortions generated by the comb filter structure are spread over the entire listening
range via broadband (wider than 1/3 bandwidth) pseudo-directivity neutral correction It is
acoustically minimized (especially with the help of masking effects in human perception of
acoustic stimuli).
Furthermore, according to aspect 21, the modulation of the headphone acoustic transducer
system with respect to the electrical transmission characteristics by means of the amplifier may
be carried out to embody the following requirements. SN ratio greater than 96 dB, loudness
range greater than 60 dB, linear distortion less than 0.5 dB (maximum shift), and nonlinear
distortion less than 0.1%.
The advantages obtained by the invention in comparison with the prior art are, in particular: a)
Horizontal forward localization (stage effect) is realized independently of the procedure used for
recording (eg, mono or stereo such as support point technology, artificial head technology) b)
Forward localization up to now Reduction of the stereo base width that occurred at the
occurrence of (for example, according to the prior art, headphone sound that allows about 10
centimeters forward localization in front of the front from 180 ° of normal sound radiation of
stereo headphones oriented up in the head) It has been found that the recommended stereo
panorama) up to the 120 ° aperture angle of the transducer system is quite small (here the
moving distance is short, greater than 160 °), c) individual types of headphones Especially the
frequency response and the acoustic transducer system, since the Not having to be considered, d)
being able to freely determine the type and time point of the desired movement in the
localization of the signal associated with the head, and e) the upward positioning in the head in
relation to the “forward” emphasis in directivity Due to the lack of knowledge or scientific
discourse on the presence of the compensating acoustic transducer moving in the "downward"
direction (see above) which cancels out, via the sound emission of the headphones, for example,
the actual space acoustic characteristics of the concert hall Can be generated independently of
the acoustic signal source (headphone quadraphony. Downward movement, which is
predominantly superior to that of the headphone acoustic transducer system, compared to
forward movement with respect to the travel distance, mainly froward-up localization in the head,
low proportion of the forward sound position determination of the "intended" signal intended).
Will save more than half of the travel distance required to indicate an appropriate auditory event,
g) thus possibly resulting from the placement of the acoustic transducer in front of the pinna that
allows forward localization The bass loss is reduced to a low value and, besides the intermediate
frequency / high frequency acoustic conversion, not require an additional bass transducer
system directly in the pinna, h) using at least one of an artificial head and a directional mixing
sole, and As a result of the recording method using the average directional characteristics of the
ear, the directionally correct reproduction of the sound will take place as the in-head upward
localization is reduced individually. Downwards "playback compensation corrections are
performed with significant average corrections, i) thus enhancing the direct positioning
information configured by artificial head recording to distinguish between" front "and" back ", j
For this reason, the introduction of the "average" filter also promises success in order to perform
the desired action on the headphone sound location (compared, the "average" compensation
correction is reproduced via the headphones) Providing a better forward localization than a
sound source that is not corrected and received "forward" from the artificial head only, k) directs
the horizontal forward positioning of the auditory event for the individual action in the form of
the pinna 1 Measured geometry (three-dimensional) "average" arrangement of a pair (of stereo
headphones) of acoustic transducers gives rise to the perception of frontal sound stimuli
(prerequisite: a person with healthy auditory tissue , L) Electrical, filter constrained, head related,
required for individual forward correction (the need for an acoustically inactive, ie less reflective,
expensive measuring chamber) It has now been found that the cost for the measurement
technique is cost-wise more favorable, including m) eg on telecommunications (aural (speaker)
events and on monitor images placed in front of oneself) A visual use of stereo headphones
allowing for forward localization), as well as the usual hi-fi applications.
The present invention will now be described in detail with reference to the drawings.
First of all, to the test subject who received the sound from the headphone set, all the important
effects of the test for locating the aural events typical of the present invention will be explained.
The special parts of this are generally a) auditory events located upwards in the head (ie, placed
90 degrees "at the top of the head") and b) located in the front outside of the head (ie The correct
discriminability and classability of auditory events, which were placed at 0 degree horizontal
direction in the frontal direction. This was indicated by the person performing the study.
Once there is a flowing transition between a) and b), an imminent (preceding) test to determine
where a new headphone acoustic transducer must be located, in particular to allow forward
localization. For example, an auditory event must be located that is perceived to be at a 45
degree angle in the frontal direction (in the bisector plane) of the chisel. The ability to locate this
sound has gained particular importance. The aim of this is to realize a horizontal forward
localization according to b) at any time by means of the headphone acoustic transducer system
being moved, while the test subject itself usually listens to perceived perceived music Was an
independent one.
This is termed "stage effect". The reason is that the location of the subjectively perceived auditory
event is simulated as "forward". There is actually no orchestra, for example, in that place.
In connection with this, any kind of recording recorded using stereophonic sound technology is
recommended. Under certain circumstances, artificial head music works are unsuitable because
stereo headphones do not find clear in-head upward localization.
Before the test object constitutes a "stage effect", ie before horizontal front localization, an
overview of the procedure mode must be predetermined. FIG. 1 shows a component 1 for
positioning the sound source with a stereo headphone acoustic transducer system which has not
been corrected, ie mounted according to the manufacturer's instructions, with the aid of a vector
representation on the median plane. 5 shows the contour of one headphone cup. This localization
corresponds to the intra-head upward localization 1 of the auditory event whose sound is emitted
by the stereo headphones. The second vector 2 forms a compensation direction "down" when the
position of the stereo headphone acoustic transducer system is moved. Thereby, the positioning
portion of the sound source with respect to the upper head 1 is removed. Vector 3 represents an
emphasis on the perception of the direction of the auditory event as being forward, i.e. being a
"stage effect". Here, stereo headphones (represented by the contours of the headphone cup) worn
on the outer ear according to the manufacturer's instructions are moved to a position allowing
forward localization of the auditory event according to motion vectors 2 and 3 (FIG. 1 See part 6
of Also, the headphone's acoustic transducer system 6 is moved to the outer ear 4 at an angle of,
for example, 30 degrees for acoustic effects (according to the perspective representation of the
contour in the headphone acoustic transducer system 6). The direction in which the sound
spreads is represented here by the vector 7.
According to FIG. 1, those procedures which are dealt with schematically and theoretically are of
equal value to the implementation. Here, it is important to add a sound, for example music, again
in stereo with headphones to the test object. All commercially available products are suitable as
test headphones, which a) operate on the "open" principle and b) surround the ear, c) with
adjustable headbands and d) several And (e) an acoustic transducer system for each channel
corresponds to a point source. For example, a broad surface radiator with dimensions of 100 mm
x 100 mm is (completely) unsuitable within the context of a direction finding test. The following
iterative method is adopted for the hidden aim of horizontal forward localization of auditory
Initially, stereo headphones are placed as directed by the producer, and then the signal
modulator of the acoustic transducer is operated. Next, the headphone acoustic transducer
system on both sides (right and left) is lifted almost enough (about 5 to 10 mm) from the surface
on the head / temple side with both hands so that the headphone pad just touches the pinna Do.
Then, while the headphone acoustic transducer system points at the spatial position of the
auditory event in steps smaller than 5 mm in each case (in each case) forward (in the frontal
direction) and downwards (at right angles to the frontal horizontal direction) It is moved.
In general, after a two-dimensional travel distance of 15 mm, a shift in the localization of the
auditory event occurs (e.g. 30 degrees elevation elevation in the median plane). This implements
the movement process of stereo headphones. It is no longer changing now but is made
dependent on the case of individual movements in the positioning of the auditory event. In the
example just described, at a 30 degree elevation, proper forward emphasis on auditory events
can already be assumed. For this reason, an additional compensating movement reaching a few
mm downwards is recommended (directed in the opposite direction to the head up). If this
movement results in a position for an auditory event that does not yet correspond to horizontal
frontal localization, the downward movement just performed is halved, ie reduced by half, for a
selected distance of mm order . Then, the required "stage effect" is optimized in an empirical way,
with added or subtracted, and further reduced movement steps. In this example, a 1-2 mm
forward movement is first selected, and only after this is a further empirical equilibrium
movement process performed.
Finally, when a new position of the stereo headphone which allows forward localization is found:
a) a small auxiliary movement of about 1 mm downward is added, b) both to increase the sound
emission efficiency of the ear canal A headphone acoustic transducer system is placed at an
angle towards the pinna / otona (about 20 to 40 degrees azimuth and elevation in horizontal and
median planes). If now the perceived position of the auditory event changes, but not favorably,
the small correction movement of the headphone acoustic transducer system (see above,
"Empirical, balanced transfer process") takes place one more time, Is held at an angle.
To provide an example, a headphone model that is widely available commercially (open, covering
the ear) and has a circular acoustic transducer (approximately 30 mm in diameter), 45 mm
vertically downward A final travel distance of (azimuth / elevation 35 degrees) is obtained. On
the other hand, when the Walkman (trade name) headphone model is used, the one with the final
movement distance which is smaller by about 50% is used. Here, the auditory organ (channel) is
used as a reference point, in front of which a headphone, which is worn according to the
manufacturer's instructions, is usually arranged centrally. For the test object this corresponds to
the current ratio (ratio of down travel distance to horizontal travel distance) 3: 1 (down 45 mm:
forward 15 mm). For exchangeable multi-channel acoustic radiation of the external ear, (for each
pinna) (directly, ie processed) to the front of the acoustic transducer system that allows forward
localization and is located forward and downward No sound signal) put a second acoustic
transducer system (modulation with spatial reflectance pattern). It is normally placed in front of
the pinna according to the manufacturer's instructions, moved back and down based on the
auditory organ reference point, and finally put in place according to the manufacturer's
instructions. With regard to finding the rest (resting) position for a sound transducer that is
suitable for this, the above procedure steps are carried out. In connection with this, the minimum
travel distance that produces the greatest effect is determined. This results in a "virtual" aural
event in which the sound is lightly backward localized when its acoustic transducer system
placed below and behind is modulated with a stereo audio signal.
Since the general backward and downward positioning of the acoustic transducer system for the
backward localization of auditory events emitting sound using stereo headphones is too
expensive, the external ear ("Anatomy Poor practicality due to the shape of “direction
dependent film”.
Finally, acoustic transducer systems placed forward and downward [I] and backward and
downward [II] are direct speech signals for [I] originally assigned, and [II] ] Is modulated with the
audio signal of the spatial reflection pattern, and then the auditory event is presented.
The auditory event is reevaluated three-dimensionally with respect to space and spread once
This position relative to the stereo headphone acoustic transducer system, which also allows
forward localization, is kept constant until the collection of data in the geometry of the geometry
and the collection of the external ear attenuation factor.
The measurement of linear distortion when the headphones are moved, in order to simulate the
forward localization independent of the movement of the direction, a frequency-dependent
difference level is formed, according to the present invention, The required, additive, continued
pre-emphasis of the stereo headphone acoustic transducer system is obtained as follows.
That is, first, a suitable probe is embedded about 4 mm in the ear canal. In this context,
appropriate means that the probe as modified later does not handle the measurement as a whole
(volume range> 58 dB, harmonic distortion <0.1%, frequency response 20 Hz to 20 kHz) or
testing It means that it does not hurt the subject. (The probe is a microminiature microphone
capsule that takes audio signal samples from the ear canal (channel) through a sound supply
similar to a hose. )
Later, to use the so-called "digital microphone" (known in recording studios) for further digital
processing of the signal, it is made more sensitive. Appropriate types are not currently available
on the market.
The (analog) electrical alternating signal (about 10 mV) generated by the microminiature
microphone is typically amplified to a voltage level higher than 0.5V. The reason is that, before
the actual EDP (Electronic Data Processing) device, the analog-to-digital converter used to
process the signal further does not work well in the quantization area, and hence insufficient
release or This is because the audio signal sampling quality will be provided.
From a number of measurements, a 20 Hz to 20 kHz sinusoidal sweep was selected. The reason
is that the immediate response of the external ear headphone acoustic transducer system is to
create level variations in the process in a frequency dependent manner that forms the basis of
the method. A sound level of 75 dBSPL or less is usually selected.
A subsequent formation of a difference signal level consisting of a representative frequency
response diagram “Headphones Normal” (placed on the pinna according to the manufacturer's
instructions) and “changed position”, ie The difference level value between the level value of
the diagram named “1” (diagram “Headphones normal”) and the diagram named the second
one (diagram ““ changed position ”) is, for example, the characteristic shown in FIG. It
corresponds to the figure. It was recorded using the outer ear of one individual (in the direction
towards "average" sound position determination).
First, two wideband 4 dB increases, centered at 1.8 and 3.6 Hz, draw attention, and a broadband
18 dB attenuation between 5 kHz and 8 kHz draws attention. Second, narrow band castles with
resonance centered at 4.8 kHz (maximum level 5.5 dB), resonance centered at 8.5 kHz (maximum
level 3 dB), and insertion at 11 kHz (minimum level minus 7 dB) The resonance can be
recognized. The resonance and damping alternate at a period of about 2 kHz in a manner similar
to a comb filter from about 12 kHz.
The differential level frequency response graph measured by one person (No. 1) no longer
contains any differences in level below the 1 kHz frequency. They relate to the forward
localization generated by the headphones. This is correct and has general validity. The reason is
that a) due to the size of the outer ear, the shape of the outer ear can function as an acoustic
damper and acoustic resonator only at frequencies above about 1 kHz, and b) the frequency
response continues up to the bass sector Degrading is because the manufacturer's instructions
indicate that the efficiency of the "open" acoustic transducer system is reduced with stereo
headphones that were not placed (mounted) in the outer ear.
For this reason, it is investigated whether the frequency response region lower than this should
be effectively extended by at least one of additional level enhancement (for example, 1/3 wide +
3 dB at 300 Hz) and degradation. To improve the audio signal broadband horizontal forward
localization of the event, the area is revisited by an audiometric test.
In contrast to the other difference level diagrams, the relative decrease of the frequency response
below 1.8 kHz, the decrease in the 5-8 kHz region, between 1.5-5 kHz and 8 kHz and here
especially The ones averaged over 12 kHz are particularly embodied here.
The salient points in the frequency response can be distributed over a range of hundreds of
hertz. Furthermore, a relative emphasis of about one third the width (1-3 dB) can be seen
sporadically below 500 Hz. A noticeable bass insertion of -10 dB to the continuous drop of the
frequency response towards lower frequencies (about 5 dB compared to the 1 kHz level value)
was caused by an error during the measurement.
This is supported by FIG. 3 which shows a further recording of the linear distortion according to
the current arrangement in the stereo headphones of the acoustic transducer allowing forward
localization. Another volunteer (second) conducted the test for the measurements shown in FIG.
Despite the various anatomic features of the test subject I and II external ear, there was a high
correlation in the important frequency range between both difference level graphs (see FIGS. 2
and 3). It is supported by values exceeding levels at frequencies below 2 kHz, 4 kHz and 8 kHz
and damping insertion of frequencies centered at 6 kHz and 11 kHz. Similarly, in FIG. 3, a
continuous drop to a low frequency response signal can be determined. This is also seen in the
figure and is similar to that in FIG.
According to the basic configuration (claim 1) of the present invention, the arrangement of the
acoustic transducers of the stereo headphone can be determined quickly and reliably and the
forward localization of the auditory event can be surely achieved. Furthermore, the features of
the respective dependent claims achieve their respective specific effects as detailed in the text.
Brief description of the drawings
FIG. 1 FIG. 1 is a vector of components located on a vertical plane and indicating the position of
the sound occurring during the process of moving the headphone acoustic transducer of a
conventional stereo headphone in a position allowing forward localization of auditory events
according to the invention Show.
2 and 3 show the test object No. 1 generated by the simulation of forward localization according
to the present invention. The frequency characteristic of the level to 1 is shown.
3 and FIG. FIG. 3 shows frequency characteristics of the same level as FIG.
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