JP3397785B2 - Method for optimizing the arrangement of stereo headphones and its acoustic transducer - Google Patents

Abstract

By means of an iteratively produced shift in both acoustic-transducer systems of a stereo headset, the shift being principally downwards and forwards with respect to the line of vision, starting from the reference position used in conventional acoustic-transducer installations in the earpiece, an auditory event is produced which is located substantially horizontally in front of the listener. The most important component of the empirical iterative process is a compensating shift in the headphone acoustic transducers by vector addition in a downwards direction relative to the up-in-head localization which usually occurs with head-specific exposure to acoustic waves. The frequency-dependent differences in sound level which occur, in contrast to conventional acoustic-transducer installations, as a result of this combined shift in the acoustic-transducer systems are used in the same way for a separate multi-channel antidistortion concept in conventional stereo headphones to give an individually simulated "horizontally in front" auditory environment. Sound stimuli of this kind located horizontally in front of the listener are produced independently of the recorded sound and recording technique to be reproduced by the stereo headphones. The result is an increase in quality of the auditory events generated by the stereo headphones in the context of the multi-dimensional reproduction in space of concert-hall acoustics for instance.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD OF THE INVENTION

The present invention relates to a method for optimizing the layout of stereo headphones of the type described in the preamble of claim 1 and their acoustic transducers. That is, the present invention has a plurality of (that is, one for each of the left and right) acoustic transducers, and the acoustic transducers can be moved by a predetermined amount in the front direction, starting from the position of attachment (reference) to the external ear protuberance. The present invention relates to stereo headphones that are arranged.

[0002]

[Prior art and problems]

Headphones for out-of-head localization of auditory events are known to be modified free or diffuse sound fields, or neutrally compensated for direction (K.
Genuit: “Warum Freifeld“ Report to the Berlin Radi
o Exhibition “, 1983; Rundfunktechnische Mitteilunge
n (Radio Technology Report), Volume 1/1983, pp. 17-26, German Patent No. 3131347, Fortschritte der Akustik.
(Development of acoustic technology) -DAGA 1987, pp. 477-480).

The basis of this known method is to simulate the performance of the human ear for a directional localization, which is well defined to be satisfactory. That is, it takes into account the upper parts of the body, the torso, the head, and the outer parts of the ears.
They are considered as units in the implementation and modification of artificial heads, directional mixing consoles, and headphones. In this area, there are currently two main developments in artificial heads today. These types can be classified into those with free-field correction and those with diffuse-field correction (Brueel & Kjaer catalog: “Head an
d Trunk Simulator 4128 ", German Patent Publication No. 3146706; Rundfunktechnische Mitteilungen (Radio Technology Report), Volume 1/1981, pp. 1-6.
Only two directional mixing consoles have been developed, based mainly on the free field transmission of the sound field (HEAD-
ACUSTICS: information pamphlet and report of the 13
th Audio Operators Convention, Munich, 1984,
103-110 pages, AKUTISCHE U.KINO-GERAETE, information pamphlet). Reference is made to various aspects regarding the specific importance of individual adjustments of the "artificial headphone" device (J. Blauert: Spatial Audition, Postscr.
ipt, new Developments and Trends since 1972, S.Hirz
el publisher, 1985, Acustica: 48, pages 272-274). Here, we pay particular attention to simulating the human ear's ability for directional localization, which must be considered in the method of transmitting audio signals, with an accuracy of 1 dB. For frequency response deviations greater than 1 dB, intracranial localization of auditory events cannot be avoided otherwise. The reason is that in the case of playback with headphones, the procedure of assigning audible events to sound sources is
This is because it lacks the visual cues (information) required to carry out the binding (G.Plenge: Problem of the Intracranial L
ocalization of Sound Source in Human Acoustic Perc
eption, Habilitation, TU-Berlin 1973, pages 25 and below). Therefore, it is of considerable importance to compensate for the single stereo sound signal of the artificial head, or of the directional console, which makes possible head localization individually and directionally in front of the headphones (these). Is suitable for recording devices) (F. Koenig: German Patent Publication No. 3922118).

In addition to this, the measurement method, the design of the measurement device, and the result obtained are as described above in connection with the determination of the transmission function of the outer ear (above, Blauert: Spatial Auditi.
on, Postscript)).

Obtained as a simplified procedure that works faster (for example, a figure is obtained after a measurement time of only a few seconds, which makes it possible to draw conclusions regarding frequency-dependent distortion). ", Regarding F. Koenig
(See German Patent Publication Nos. 3903246 and 39 12 582).

For recording and playback of directionally true acoustic radiation, Blau is used to reduce the noisy side effect of “intracranial localization” in the playback of recordings via acoustic radiation using headphones.
ert / Boerger / Lams / Kuerer / Plenge / Wilkens / Pfleiderer
Efforts have been made (German Patent Publication No. 22
No. 3316, No. 2628053, each specification, No. 1927401, No. 224416
No. 2, 2545446, 2557519, Funk Tech
nik (wireless technology) 6,7 / 1984, special edition, German Patent Publication No. 3112874).

Particular emphasis can be placed on the last process (PMPfleiderer's). The reason is that it provides a non-localization of auditory events corresponding to scientific terms when used in good approximation for implementation, as published in "Processors for External Localization of the Head". Yes (above, G
Plenge, habilitation publication, 1973,). This device is a fairly efficient processor, which composes a stereo sound followed by a spatial sound, but does not realize one close to the direction of the sound possible in the natural three-dimensional localization of an auditory event (from the upper head localization). Divergence). As already mentioned, the directivity of the outer ear contributes to this (Blauert, Spatial Audit, supra).
See ion and Postscript).

Many papers, publications and patent applications have emerged regarding effective processors and their technical implementation.
They specifically describe the simulation of spatial reflection patterns. Accordingly, a wide range of such variably programmable reverberator and echo devices (including spatial dimensions, spatial structure and spatial design) are available today.

In addition, “new type of presence filter” (J. Blau
ert: Fernseh-und Kino-Technik (Technology of Television and Movies 1970, 3, Vol. 75-78) has been known since 1970, and also "a model for describing the characteristics of outer ear transmission". Are known. There, "forward" and "horizontal" in front of the head and at the ear
Correction of differences during changes in the direction of incidence of sound up to (K. Genuit: PhD dissertation, Aachen University of Science and Technology, 198
4,81-82).

Finally, it is known that the acoustic transducer system of the headphones can be more or less exactly horizontally localized to the front when the auditory event is moved forward in the viewing direction.
This is because certain linear corrections are made while the pinna are receiving a close range of sound radiation. Here, in order to achieve said effect, the acoustic transducer must be placed at least about 10 cm forward in the viewing direction. Horizontal localization of auditory events is via acoustic emission using stereo headphones. This is supported by stereo headphones, which are expensive to implement. this is,
Provided separately and separately modulated bass and mid / treble acoustic transducer systems, parallel to the left and right pinna to emit sound (German DE 2541332; Funkschau (Radio Review): 10/1977, 57-58 and 71-72).

A stereo headphone of the type mentioned at the outset (preceding claim 1) is known from US Pat. No. 3,592,978. This known stereo headphone has an acoustic transducer system. This acoustic transducer system is not normally mounted directly at the external ear protuberance, but rather by being moved forward a certain amount in the viewing direction, at a distance from the external ear protuberance about the vertical axis. It has been pivoted. However, the distance that the sound moves in the forward direction is very small, so at least in the viewing direction.
Unlike the case of the acoustic transducer arrangement described above which moves 10 cm, it is by no means sufficient to achieve a horizontal anterior localization of an auditory event. The reason is that U.S. Pat. No. 3,592,978 does not discuss at all how to achieve horizontal anterior localization of auditory events. As is true, the in-head superior localization of conventional headphones is maintained for this known stereo headphone. The stereo headphones produce sound unnaturally and can be annoying when listening for a long time.

Another known stereo headphone of the type mentioned at the beginning (preceding claim 1) is known from US Pat. No. 3,751,608. The known headphones provide an acoustic transducer system arrangement similar to that known from US Pat. No. 3,592,978. That is, it is pivoted (turned) in the front direction at a certain lateral distance from the outer ear protrusion. This known stereo headphone is characterized by a frontal sound effector system arrangement, which is too small for a frontal localization of an auditory event. Furthermore, from US Pat. No. 3,751,608 is known a method for optimizing an acoustic transducer system of the type described below. That is, this method starts from the reference arrangement position of the acoustic transducer mounted on the external ear protuberance to be tested, and experimentally optimizes the arrangement of the acoustic transducers by moving each acoustic transducer to make a frontal direction. This is a method for optimizing the placement of the left and right acoustic transducers of stereo headphones that localize auditory events. Correspondingly, auditory events can be created, in particular by experimentally optimizing the repositioning of the acoustic transducer systems on both sides, in the frontal direction.

[0013]

[Problems to be Solved by the Invention]

The object of the first aspect of the invention is to provide a stereo headphone of the kind described in the opening paragraph (preceding claim 1), which is improved in such a way that forward localization of auditory events is reliably achieved by simple means. It is to be. The second aspect of the present invention
The objective in view of is to provide a method for optimizing the placement of acoustic transducers in stereo headphones of the type described above, which allows the placement of acoustic transducers to be determined quickly and reliably.

[0014]

[Means for solving the problem]

The object of the first aspect of the present invention is achieved by the configuration described in the characterizing part of Claim 1 or the latter part of the stereo headphones. That is, the stereo headphones have one left and right acoustic transducers, and the acoustic transducers are moved and arranged by a predetermined amount in the front direction starting from the mounting reference position on the external ear protuberance. Inside, each of the acoustic transducers can be further moved downward in the frontal direction, and by an amount suitable for converting the intracranial upper localization to an auditory event that localizes in the substantially frontal direction, beyond the amount of movement in the frontal direction. It is characterized by being configured.

A preferred embodiment (aspect 2) of the stereo headphones of the invention is provided by claim 2. That is, the acoustic transducer is three-dimensional because of either 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 of the auditory event horizontal anterior. It is characterized in that it can be variably arranged. (Aspect 2)

Regarding the method according to the second aspect of the present invention, starting from the reference arrangement position of the acoustic transducers mounted on the external ear protuberance to be tested, the acoustic transducers are arranged by moving each acoustic transducer. It is a method of optimizing experimentally to localize auditory events in the front direction, optimizing the placement of the left and right acoustic transducers of stereo headphones, and the method of optimizing the acoustic transducers of stereo headphones for the frontal localization of auditory events. By repeatedly moving the placement of each acoustic transducer alternately downward and forward with a predetermined step size to optimize the placement, a further forward movement is performed for the frontal localization of the auditory event. A method is provided for optimizing the placement of acoustic transducers in stereo headphones, which is characterized by moving over a quantity. (Aspect 3)

[0017]

DETAILED DESCRIPTION OF THE INVENTION

The preferred embodiments of the present invention are as follows. (Mode 4) A mode in which the predetermined step width is smaller than 5 millimeters. (Aspect 5) An acoustic transducer of a stereo headphone is provided with respect to an auditory canal for at least one of increasing acoustic emission efficiency in the external ear protuberance and optimizing positioning performance of the acoustic transducer to the external ear protuberance. An aspect characterized by arranging it diagonally. (Aspect 6) An aspect characterized in that the iterative determination of the optimal placement of the acoustic transducers is performed separately for the left ear and the right ear of the test subject. (Aspect 7) An aspect characterized in that the optimal placement of the acoustic transducers is determined by a plurality of stereo audio signals that change during the determination process. (Aspect 8) An aspect in which the optimum placement of the acoustic transducers is determined by at least four movement procedures that should be newly repeated in each case. (Aspect 9) An aspect, characterized in that, in order to determine the optimal placement of the acoustic transducers, one of the at least four movement procedures is selected that has a number of typical features of the others. (Aspect 10) An aspect characterized by executing a moving procedure for a plurality of test objects. Embodiment 11 An embodiment characterized in that at least eight volunteers who are healthy with respect to the hearing organ are used to determine the optimal placement of the acoustic transducers. (Aspect 12) A method comprising averaging individual results. (Aspect 13) With respect to the angle of inclination of the acoustic transducer and the forward downward movement distance, the optimal placement 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. Aspect characterized by the above. (Aspect 14) By the ratio of the upward moving distance and the downward moving distance,
Stereo headphones that are optimized and / or minimized with respect to distance traveled, based on the usual geometrical (three-dimensional) arrangement of acoustic transducers for intracerebral superior localization of auditory events greater than 2-1 The acoustic transducer geometry of is selected in front of and forward of the auditory event. (Aspect 15) In order to generate a multidimensional spatial acoustic auditory event, the acoustic transducer is supplied with a stereo audio signal of a sound source for a frontal auditory event, and the acoustic transducer is arranged so that the auditory sense at an upper intracranial position. Aspects of selecting a stereo indirect sound derived from a stereo audio signal of the sound source for an event. (Aspect 16) In order to extend a multi-dimensional spatial auditory event for intracranial supralocation with multi-channel stereo headphones, the acoustic transducers are arranged in at least one of a rear direction and a lower direction opposite to the front direction. A mode in which the movement is performed so as to match the directional auditory event. (Aspect 17) Freedom between acoustic transducers to produce auditory events with intracranial superior localization, frontal localization and multidimensional spatial acoustic properties for comparison and / or measurement purposes of auditory events. A method characterized by performing selectable switching to. (Aspect 18) At least one of a headphone cup and a stereo headphone is provided in order to surely place the acoustic transducer of the stereo headphones in the rest position thereof so that at least one of the frontal localization and the in-head superior localization of the auditory event can be realized. An embodiment, wherein a headphone pad used for centering at least one of the auricle and the front of the auricle is filled with a substance capable of transmitting sound and applying elastic stress. (Aspect 19) A bass and midrange transmission range is coupled to the head and at least one of a headphone ear pad and a cup structure and a playback frequency response of an acoustic transducer to form a neutral acoustic auditory event. An aspect characterized by adjusting by at least one of correction. (Aspect 20) In at least one of the upper middle transmission range and the top transmission range of an acoustic transducer in stereo headphones compared to the distortion that occurs in the occurrence of a frontal localization of an auditory event that is linear and comb-shaped. A mode in which a relatively wide band correction that causes a neutral state of an acoustic pattern is performed. (Aspect 21) An aspect characterized in that the volume of audio signals for setting the volume of an acoustic transducer whose amplitude can be controlled is set by separate multi-channel amplification.

The essence of the invention consists of vectorial partial acoustic direction “bottom” compensation that disturbs the intracranial upper localization and directional “forward” additive compensation. It is applied to produce a) an external localization away from the head, or b) a horizontal anterior localization of an auditory event (which is separate from the recording method, eg canning of sound).

In other words, in the short-range acoustic radiation under test, the perception of directionality as being “horizontally forward” during stereo sound reproduction, eg associated with the head of an artificial head sound recording, is Two components of sound directivity, rather than being ensured (accuracy by 1 dB) by the individual directivity (indication to) characteristics of the human anatomical hearing, which is specific to the direction of incidence of It is secured by the combination of "lower" and "front".

In this context, if there is an overall neglect of the “down” compensation movement (of the headphone acoustic transducer system) according to the present invention, the directional characteristic of the individual is a threshold of 1 dB. The same undesired perception of the direction of the auditory event results, as indicated when exceeded. That is, the auditory event is perceived as being in the frontal direction, but it is localized obliquely upward about 45 ° (almost in the head. This is a characteristic feature of the known head-related stereo sound recording and reproduction processes. Equivalent to).

As a method of optimizing the placement of the headphone acoustic transducer system of the present invention, efforts are made to move the headphone acoustic transducer to minimize the distance for forward localization. For this purpose, preferably at least one of the stereo headphones with high-band diffuse sound field modification and / or the acoustic transducer of the stereo headphones is used.

Due to this process, only a downward compensating movement of the stereo headphone acoustic transducer device is used to realize a “virtual auditory event” whose directivity cannot be clearly determined (but emphasizes only the forward direction). Thus, it is better to cancel the normal localization of the above-intracranial auditory events.

Furthermore, in order to realize the auditory event in the horizontal direction opposite to the frontal direction, in other words, in the rearward direction, in order to realize the auditory event, the left and right channels of both auditory events modified for forward localization of the auditory event. It is better to replace

Also, when a multi-channel acoustic transducer system is used to produce improved spatiality and spatial acoustics for each auricle exposed to sound, the anterior-downward direction is due to the anterior localization of auditory events. In addition to the headphone sound transducer system that is placed, the placement of the headphone sound transducer system on the side opposite to the front direction and below the outer ear structure,
It is also advantageous to choose according to embodiment 16. According to aspect 15, all four acoustic transducers are separately modulated.

In addition to this, according to 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 upper body and head response. . This is, for example, BLAUERT and GAN
More detailed by UIT. This is particularly advantageous for the headphone design of the present invention.

In its design, that is,
In its transmission properties, it is particularly modified according to the theoretical signal transmission base (eg in reflective space). This is no longer adhered exactly when it deviates from the traditional positioning of the acoustic transducer system,
Adjustment of the acoustic pattern (eg, diffuse sound field post-emphasis) is performed according to the configuration of embodiment 19 or 20. Here, the narrowband (narrower than one-third bandwidth) distortion generated by the comb filter structure is
A band width wider than one-third) is acoustically minimized over the entire listening range via a pseudo-directional neutral correction (especially utilizing the masking effect in the perception of human acoustic stimuli).

Furthermore, according to an aspect 21, the modulation of the headphone acoustic transducer system with respect to electrical transmission characteristics by means of an amplifier may be performed to embody the following requirements. That is: -SN ratio greater than 96 dB, volume range wider than 60 dB, linear distortion (maximum deviation) smaller than 0.5 dB, and non-linear distortion smaller than 0.1%.

The advantages obtained by the present invention in comparison with the prior art are, among others: a) horizontal front localization (stage effect) is achieved independent of the procedure used for recording (eg monaural or stereo like support point technology, artificial head technology), b) forward localization up to now. The reduction of the stereo base width that has occurred during the occurrence of the
It has been found that the recommended stereo panorama from ° to the 120 ° aperture angle of the headphone acoustic transducer system, which allows a frontal localization of about 10 cm in the front direction, is quite small (here, movement (Because the distance is short, it is larger than 160 °), and c) the efficiency of the individual localization correction of the headphone type remains almost unaffected, so that it is not necessary to consider especially the frequency response and the acoustic transducer system. D) the freedom to determine the type and time of movement desired in the localization of signals related to the head, e) in relation to the "forward" emphasis on directivity,
Because of the lack of knowledge or scientific discourse about the existence of compensating acoustic transducers that move in a “downward” direction that counteracts the supraorientation of the head (see above), through the sound emission of headphones, for example in a concert hall, The actual spatial acoustic characteristics can be generated independently of the acoustic signal source (headphone quadraphony, mainly in the upper head of the head, see low proportion of forward sound localization of "intended forward" signals), f) Compared to the forward movement with respect to the distance traveled, the significantly predominant downward movement of the headphone acoustic transducer system saves more than half of the distance traveled required to indicate a proper auditory event, g) , In some cases, the bass loss caused by the acoustic transducer arrangement in front of the auricle, which enables anterior localization, is reduced to a small value, Other than frequency acoustic conversion, no additional bass transducer system is required directly in the auricle, h) As a result of the recording method using at least one of an artificial head and a directional mixing sole, and using the average directional characteristics of the ear, Individually reduced upper intracerebral localization results in directionally accurate sound reproduction, but "down"
The playback compensation correction is done with a significant average correction, i) thus intensifying the direct positioning information, which is especially constituted by the artificial head recording to distinguish between "front" and "back", j) this For that reason, the introduction of an "average" filter also promises success in order to achieve the desired effect on the headphone placement position (comparative, the "average" compensation correction is played back through the headphones and corrected). Performing a better anterior localization than a sound source received "anteriorly" only from the artificial head, not k), a set of (, which dictates the horizontal anterior positioning of the auditory event due to the individual action of the shape of the auricle. Stereo headphones)
That the measured geometrical (three-dimensional) "mean" placement of the acoustic transducers results in the perception of frontal sound stimuli (prerequisite: healthy human hearing), l) electrical, filter For measurement techniques (including the need for costly measurement chambers that are acoustically inactive, i.e., low in reflection), which were sought after for head-related, individual head-correction It has now been found that costs are more cost-effective, m) e.g. telecommunications (audible (speaker) events and visual events on monitor images located in front of him).
At the same time, it is possible to provide a possible use of stereo headphones that allow front localization, other than normal hi-fi applications.

[0029] [Example]   Hereinafter, the present invention will be described in detail with reference to the drawings.

First of all, the test subject who receives the sound from the headphone set will be described with all of the important effects of the test for locating an auditory event that is typical for the invention. Special parts of this are a) auditory events that are generally a) located in the head above the head (ie, "at the top of the head" and vertically oriented 90 degrees), and b) are located anterior-lateral to the head (ie, The correct discriminability and categorizability of the auditory event, (positioned 0 degrees horizontally in the frontal direction). This was shown by the person performing the test.

Once there is a fluent transition between a) and b), an urgent test to determine where the position of the new headphone acoustic transducer, in particular allowing front localization, has to be located. At, for example, an auditory event perceived to be at a 45 degree angle in the frontal direction (in the bisecting plane) in front of the bat must be located. The ability to localize this sound has gained special importance. The aim of this is to achieve horizontal forward localization according to b) at any time by the headphone acoustic transducer system being moved while the test subject himself ordinarily listens to music perceived as pleasant. Was able to be independent.

This is termed the “stage effect”. The reason is that the location of the subjectively perceived auditory event is simulated as "forward". In reality, there is no orchestra, for example.

In this connection, any kind of recording recorded using stereophonic techniques is recommended. Artificial head music works are unsuitable because under certain circumstances stereo headphones do not find a clear intracerebral localization.

Before the test object constitutes the “stage effect”, ie before the horizontal anterior localization, an overview of its procedural mode must be predetermined. FIG. 1 shows a component 1 for locating a sound source with a stereo headphone acoustic transducer system unmodified, ie fitted according to the manufacturer's instructions, with the help of a vector representation on the midplane. Reference numeral 5 shows the outline of one headphone cup. This localization corresponds to an intracranial superior localization 1 of an auditory event in which sound is emitted by stereo headphones. The second vector 2 forms the compensation direction “down” when the position of the stereo headphone acoustic transducer system is moved. As a result, the positioning portion of the sound source with respect to the upper part of the head 1 is removed. Vector 3 represents the perceptual emphasis of the direction of the auditory event as being anterior, ie a “stage effect”. Here, a stereo headphone (represented by the outline of a headphone cup) worn on the outer ear according to the manufacturer's instructions is moved to a position that allows forward localization of an auditory event according to motion vectors 2 and 3 (FIG. 1). Section 6). In addition, the headphone acoustic transducer system 6
It is moved to the outer ear 4 at an angle of, for example, 30 degrees for acoustic effects (according to a perspective representation of the contour in the headphone sound transducer system 6). The direction in which the sound spreads is represented here by vector 7.

According to FIG. 1, those procedures which are dealt with roughly in theory are worth the implementation. Here, it is important to add to the test object a sound, for example music, again in stereo via headphones. All products on the market are suitable as test headphones, which are: a) working on the "open" principle, and b) surrounding the ear, c) with an adjustable headband, and d) multiple. And (e) the acoustic transducer system for each channel corresponds to a point source. For example, a large surface radiator with dimensions 100 mm x 100 mm is (fully) unsuitable within the context of direction finding tests. For the hidden aim of horizontal anterior localization of auditory events, the following iterative procedure is adopted.

First, the stereo headphones are placed as directed by the manufacturer, and then the signal modulator of the acoustic transducer is activated. Then, the (left and right) headphone acoustic transducer system on both sides is lifted from the head / temporal surface almost fully (about 5-10 mm) with both hands so that the headphone pad barely touches the auricle. To do. The headphone acoustic transducer system is then in each case (in each case) forward (in the front direction) and downward (in the front horizontal direction at right angles).
It is moved in steps smaller than 5 mm, paying attention to the spatial position of the auditory event.

In general, after a two-dimensional distance of movement of 15 mm, a localization shift of the auditory event occurs (for example, 30 ° forward elevation in the midplane). This realizes the moving process of stereo headphones. It no longer changes, but it makes the localization of auditory events dependent on the individual movement case. In the example just described, at an elevation angle of 30 degrees, a suitable anterior emphasis of auditory events can already be assumed. For this reason, additional compensatory movements down to a few mm are recommended (directed in the opposite direction of the supra-orientation). Assuming that this movement results in a position for an auditory event that does not correspond to horizontal anterior localization, the downward movement just made is halved, or reduced by half, for a distance of the order of mm. Then, the required "stage effect" is
Added or subtracted in an empirical way,
Optimized with further reduced movement steps.
In this example, first a forward movement of 1-2 mm is selected, and only then is the further empirical equilibrium movement process performed.

When a new position of stereo headphones that allows frontal localization is found, finally, a) a small auxiliary downward movement of about 1 mm is added, and b) both to increase the sound emission efficiency of the ear canal. Headphone acoustic transducer system is placed at an angle towards the pinna / aural canal (azimuth and elevation about 20-40 degrees in the horizontal and midline). If the perceived position of the auditory event has changed, though undesirably, then a small correction movement of the headphone acoustic transducer system (see above, "empirical, balanced transfer process") is performed once more, Is held at an angle.

To provide an example, a headphone model that is commercially widely available (open, covering the ear) and has a circular acoustic transducer (diameter is about 30 mm), vertically down 45
The final travel distance in mm (azimuth / elevation angle of 35 degrees) is obtained. On the other hand, when the Walkman (trade name) headphone model is used, the one with the final travel distance that is smaller by about 50% is used. Here, a hearing organ (channel) is used as a reference point, and in front of it, headphones to be worn according to a manufacturer's instruction are usually arranged in the center. For the test subject, this corresponds to a current ratio (ratio of downward travel to horizontal travel) of 3: 1 (45 mm down: 15 mm forward). For interchangeable multi-channel acoustic radiation of the outer ear,
A second acoustic transducer system (directly to the unprocessed audio signal) next to (near) the acoustic transducer system that allows front localization and is located in the lower front. (Modulation with spatial reflectance pattern). It is normally placed anterior to the pinna according to the manufacturer's instructions, moved backwards and downwards, based on the auditory reference point, and finally placed in position. With regard to finding a rest (rest) position for an acoustic transducer suitable for this, the above procedural steps are carried out.
In this connection, the minimum distance traveled that produces the greatest effect is determined. This results in a "virtual" auditory event in which the sound is lightly localized, when its acoustic transducer system placed below and behind is modulated with a stereo audio signal.

The general rear and bottom positioning of the acoustic transducer system for rearward localization of auditory events emitting sound using stereo headphones is too costly,
Poor in practical use due to the shape of the outer ear (“anatomical” direction-dependent filter) that results in greater travel.

Finally, the acoustic transducer systems located in the front and in the lower [I] and in the rear and the lower [II] are directly speech signals for the originally assigned [I] and also [II]. ] Is modulated with a spatial reflection pattern of the audio signal and then an auditory event is presented. The auditory event is three-dimensionally reassessed in space and spread again.

This position with respect to the stereo headphone acoustic transducer system, which also allows forward localization, remains constant until the collection of data within the geometry of the geometry and collection of the outer ear attenuation factor.

The measurement of the linear distortion when the headphones are moved is a frequency of the level is added in order to perform a forward localization simulation which is independent of the movement of the direction, and then according to the invention the stereo headphone sound. The required additive additive pre-emphasis of the converter system is obtained as follows. That is, first, a suitable probe is embedded in the ear canal for about 4 mm. Appropriate here means that the probe, which was later modified, leaves the measurement as a whole (volume range wider than 58 dB, harmonic distortion 0.1%).
Smaller, the frequency response is 20Hz to 20kHz), or that it does not damage the test object. (The probe is a miniature microphone capsule that takes audio signal samples from the ear canal (channel) via a sound supply similar to a hose.)

It is made more sensitive by using so-called “digital microphones” (known in the recording studio) for further digital processing of the signal later. Suitable types are not currently available on the market.

The (analog) electrical alternating signal (approximately 10 mV) generated by a microminiature microphone is typically amplified to voltage levels above 0.5V. This is because before the actual EDP (electronic data processing) device, the analog-to-digital converter used to further process the signal does not work well in the quantisation area and thus the insufficient release or This is because the audio signal sampling quality will be provided.

From a number of measurement methods, a 20 Hz to 20 kHz sinusoidal sweep was selected. The reason is that the immediate reaction of the outer ear headphone acoustic transducer system causes a level variation in the process in a frequency-dependent manner. Sound level is 75
Below dBSPL is usually selected.

A typical frequency response diagram “Headphones Normal” (placed on the auricle according to the manufacturer's instructions) and the subsequent formation of the difference signal level consisting of “altered position”, ie Level values in the figure named 1 (the figure of "headphones normal") and the second named (the figure of "changed position")
The difference level value between and corresponds to the characteristic diagram shown in FIG. 2, for example. It was recorded using one individual's outer ear (in the direction towards "average" sound localization).

First, two broadband 4d centered around 1.8 and 3.6Hz
An increase in B attracts attention and also a wide band 1 between 5kHz and 8kHz
8dB attenuation draws attention. Secondly, we recognize narrow-band castle resonance with resonance around 4.8kHz (maximum level 5.5dB), resonance around 8.5kHz (maximum level 3dB), and insertion at 11kHz (minimum level minus 7dB). can do. Spear shape similar to a comb filter from about 12 kHz,
Resonance and damping alternate with a period of about 2 kHz.

The difference level frequency response graph measured by one person (No. 1) no longer contains any difference in level below the frequency of 1 kHz. They relate to the frontal localization generated by the headphones. This is correct and has general relevance. The reasons are: a) Due to the size of the outer ear, the shape of the outer ear can function as an acoustic damper and an acoustic resonator only at frequencies above about 1 kHz, and b) the frequency response is continuous up to the bass sector. The decline is due to the reduced efficiency of the "open" acoustic exchanger system with stereo headphones that were not placed (weared) on the outer ear at the manufacturer's direction.

For this reason, it is investigated whether or not the lower frequency response region should be effectively expanded by an additional level improvement (for example, 1/3 wide +3 dB at 300 Hz) and / or a reduction, and the audibility is checked. To improve the audio signal broadband horizontal anterior localization of the event, the area is again scrutinized by an audiometric test.

In contrast to other difference level diagrams, a relative decrease in frequency response below 1.8 kHz and a decrease in the 5-8 kHz region, 1.
Between 5 and 5 kHz and 8 kHz, and especially here 12 kHz
What is averaged above is embodied here in particular. The points that stand out in the frequency response can be distributed over a range of hundreds of hertz. Furthermore, the relative enhancement of about one-third of the width (1 to 3 dB) can be seen sporadically below 500 Hz. -10d for continuous decrease of frequency response toward low frequency (about 5dB compared to 1kHz level value)
A noticeable bass inset of B was caused by an error during the measurement.

This is supported by FIG. 3 which shows a further recording of the linear distortion due to the current placement in the stereo headphones of the acoustic transducer allowing front localization. Another volunteer (second) performed the test for the measurements shown in FIG. With test subject I
Despite the various anatomical features of the II outer ear, there was a high correlation in the frequency range of interest between both difference level graphs (see Figures 2 and 3). 2kHz, 4kHz and
Values exceeding the level at frequencies below 8 kHz and 6 kHz
It is supported by the damping fitting of the frequency centering on 11kHz. Similarly, in FIG. 3, it is possible to determine a continuous drop to a signal with a low frequency response. This is also seen in the figure and is similar to that in FIG. [Brief description of drawings]

FIG. 1 is a diagram showing the position of the sound that occurs during the movement process of the headphone acoustic transducer of a conventional stereo headphone in a position which lies in a vertical plane and allows the frontal localization of an auditory event according to the invention. Indicates a vector.

FIG. 2 shows a level frequency characteristic with respect to a test object No. 1 generated by a forward localization simulation according to the present invention.

FIG. 3 shows frequency characteristics at the same level as in FIG. 2 for test object No. 2.

   ─────────────────────────────────────────────────── ─── Continued front page       (56) References JP-A-51-17427 (JP, A)                 58-109388 (JP, U)                 58-147387 (JP, U)                 Actual development Sho 60-160700 (JP, U)                 Actual Development Sho 53-35017 (JP, U)

Claims (2)

(57) [Claims] 1. A stereo headphone having one acoustic transducer on each of the left and right sides, starting from a mounting reference position on the external ear protuberance, and moving the acoustic transducer by a predetermined amount in the front direction. In each of the left and right cups, each of the acoustic transducers is downward in the front direction, and an amount appropriate for converting an intracranial upper localization to an auditory event that is localized in a substantially front direction.
Stereo headphones characterized in that the headphone is further movable beyond the amount of movement in the front direction. 2. The stereo headphone according to claim 1, wherein a) a stereotactic position of an auditory event above the head based on a mounting position of the acoustic transducer on the external ear projection, or b) a horizontal front of the auditory event. The stereo headphone is configured such that the acoustic transducer can be three-dimensionally variably arranged for any one of the localization positions.