EP0484354B1 - Stereo headphone for the "in front" location of auditory events generated by stereo headphones - 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

The invention relates to a stereo headphone for pre-locating hearing events generated by means of stereo headphones of the type specified in the preamble of claim 1 and a method for optimizing its sound transducer system arrangement.

It is known that headphones for an out-of-the-head localization of hearing events are equalized free-field or diffuse-field or directionally neutralized (K. Genuit: "Why Freifeld, communication to the radio exhibition Berlin 1983; Rundffunktechnische Mitteilungen: Issue 1/1983, pages 17 to 26 ; DE-A-3131347; Progress in acoustics - DAGA 1987, pages 477 to 480).
The basis of these known methods is a replica of the statistically sufficiently averaged directional characteristic of the human ear, i.e. taking into account the upper body, trunk, head and outer ear relief, which are taken into account in the implementation or equalization of an artificial head, directional mixer and headphones in a standardized manner. Today there are mainly two main types of artificial head developments, which can be divided into free-field and diffuse-field-equalized versions (Brüel & Kjaer catalog: "Head and trunk simulator 4128";
DE-A-3146706; Broadcast communications: Issue 1/1981, pages 1 to 6). So far, only two directional mixing consoles have been developed, which are mainly based on the free-field transmission of sound fields (HEAD-ACUSTICS: information brochure and report of the 13th sound engineer conference Munich 1984, pages 103 to 110; AKUSTISCHE U. KINO-GERÄTE GmbH: information brochure). The special significance of the individual adaptation of the "artificial headphones" system is pointed out from various points of view (J. Blauert: Spatial Hearing, Postscript, New Results and Trends since 1972, S. Hirzel Verlag, 1985; Acustica: Vol. 48, pages 272 to 274). Attention is drawn in particular to the 1 dB exact replica of the directional characteristic of the human ear, as is to be taken into account in a sound signal transmission process. With frequency response deviations greater than 1 dB, an in-the-head localization of hearing events is otherwise unavoidable, since the process of assigning the hearing event to the source of the sound source in the case of headphone playback lacks the additional visual information for linking (G. Plenge: About the problem of intracranial Locating sound sources in people's acoustic perception, Habilitation, TU Berlin 1973, pages 25 ff.). Thus, that the sole (the out-of-head localization enabling) stereo-audio signal is a dummy head or direction mixer prior to (to the receiving system compatible) Headphones direction dependent, nachentzerrt individually is essential (F. King; DE-A-39 22 118 ).

The measurement methods, the measurement setup and the results obtained in connection with the determination of the outer ear transfer function were also described in an overview (see above, Blauert: Spatial Hearing, Postscript).

Modified as a faster-working and simplified method (for example, graphics are available after a few seconds of measurement time, which allow conclusions about frequency-dependent distortions), this shows F. König with regard to the sound system variant "headphones" (DE-A-3903246.9 and -3912582).
Efforts to record and reproduce directional sound reinforcements have been made by Blauert / Boerger / Laws, Kürer / Plenge / Wilkens, Pleiderer etc. to reduce the annoying side effect of "in-the-head localization" when playing sound recordings using headphone sound reinforcement (DE- A-223316, -2628053; -1927401, -2244162, -2545446, -2557519; Funk Technik, issue 6 + 7/1984, reprint, DE-A-3112874.).
In particular, the latter method (by PM Pfleiderer) should be emphasized, since in practical use it does not, as propagated with "processor for out-of-head localization", offer a hearing event localization corresponding to the scientific term (see above G. Plenge, habilitation thesis , 1973). This device is an effect processor that builds up room acoustics retrospectively to stereo sound, but does not implement one of the possible sound direction perceptions (deviating from top-in-head location) in the natural three-dimensional location of hearing events. The directional characteristic of the outer ear has been shown to contribute to this (see Blauert, Spatial Hearing, Postscript above).

With regard to the effect processors and their technical implementation, a large number of dissertations, publications and patent applications have been made, which in particular describe the simulation of spatial reflection patterns. Accordingly, there is a wide range of such programmable reverb and echo devices today (including the factors of room size, composition and design).
In addition, "a new type of presence filter" (J. Blauert: Fernseh- und Kino-Technik, 1970, Issue 3, pages 75 to 78) and "a model for the description of outer ear transmission properties", based on differential equalization during the transition, have been known since 1970 from the direction of sound incidence "in front", horizontally in front of the head to "laterally" at the ear (K. Genuit: Dissertation, TH-Aachen 1984, pages 81 to 82).
Finally, it is known that by shifting headphone sound transducer systems forward in the viewing direction, hearing events can be located more or less exactly horizontally in the front, which is based on the generation of direction-specific linear distortions during the close-sound situation of the ear cup. The sound transducer arrangement must be placed at least approx. Ten centimeters in the direction of vision in order to achieve the described effect of horizontal pre-localization of hearing events via stereo headphone sound This is evidenced by elaborately designed stereo headphones, which provide bass and mid / high-range transducer systems that are separately controlled for the left and right auricles (DE-A-2 541 332; Funkschau: Issue 10/1977, pages 57 to 58 and 71 to 72).

A stereo headphone of the type mentioned in the preamble of claim 1 is known from US-A-3 592 978. In this known stereo headphones, the sound transducer systems are not arranged in the conventional manner directly on the outer ear relief but rather are pivoted about a vertical axis at a distance from the outer ear relief in such a way that they are shifted forward in the direction of view by a predetermined amount. However, this amount of shift in the forward direction is so small that it is in no way sufficient to achieve a horizontal pre-localization of hearing events, as is the case with the above-described sound transducer arrangement with a shift of at least approx. 10 cm in the forward direction of view . Accordingly, there is no indication in US-A-3,592,978 that a horizontal pre-localization of hearing events can be achieved with the stereo headphones described therein. In fact it is the case with this known stereo headphone that the top-in-head localization of conventional headphones is preserved, which is perceived as unnatural and annoying when listening for a long time.

Another stereo headphone of the type mentioned in the preamble of claim 1 is known from US-A-3 751 608. These known headphones provide a similar arrangement of the sound transducer systems as in the stereo headphones known from US-A-3 592 978, that is to say with a lateral distance from the respective outer ear relief and in the horizontal plane in the direction of view swung forward. With this known stereo headphone, too, the arrangement of the sound transducer systems in the direction of view to the front is too small due to the pivoted sound transducer system arrangement in order to be able to achieve a horizontal pre-localization of hearing events. In addition, a method for optimizing the sound transducer arrangement of a stereo headphone of the type specified in the preamble of claim 3 is known from US Pat. No. 3,751,608, accordingly it is provided that the preferred hearing event is determined empirically in an optimizing manner by varying the arrangement of the two Acoustic transducer systems, for example, looking in the forward direction.

The object of the present invention is to design a stereo headphone of the type specified in the preamble of claim 1 in such a way that a pre-localization of hearing events is reliably ensured using simple means. In addition, a method for optimizing the sound transducer systems of a stereo headphone of the type specified in the preamble of claim 3 is to be created, with which the positions of the sound transducer systems required for the pre-location in the stereo headphones according to the invention can be determined quickly and reliably.

This object is achieved with reference to the stereo headphones by the characterizing features of claim 1. An advantageous development of the stereo headphones according to the invention is specified in claim 2. With regard to the method, the invention is solved by the characterizing features of claim 3. Advantageous developments of the method according to the invention are specified in claims 4 to 21.

• a) Außer-Kopf-Lokalisation bzw.
• b) horizontalen Vorne-Ortung von Hörereignissen (unabhängig vom Tonaufzeichnungsverfahren z.B. einer Tonkonserve) zur Anwendung kommen.

Accordingly, the essence of the invention consists in the fact that a vectorial partial sound direction compensation which counteracts the top-in-the-head localization "bottom" and an additive directional embossing "front" to generate a

• a) Out-of-head localization or
• b) horizontal pre-location of hearing events (regardless of the sound recording method, for example, a sound preserve) are used.

In other words, in the vicinity of the sound of test persons, a sense of direction "horizontally in front" with head-related stereophonic reproduction of, for example, artificial head sound recordings is not only guaranteed by the (1 dB-exact) compliance with the individual directional characteristic of the human anatomical hearing, which is specific to the direction of sound "front" , but also by assembling the sound incident direction components "below" and "in front".
In this context, it should be pointed out that a general neglect of the compensation shift according to the invention “below” (from headphone / sound transducer systems) results in the same undesired hearing event directional sensation as the exceeding of the 1 dB threshold with individual directional characteristic: hearing event sensation in the viewing direction at the front, but approx. 45 degrees diagonally upwards or upwards (approximation of the top-in-head localization; this corresponds to the characteristic of known head-related stereophonic recording and playback methods).

With the method according to the invention for optimizing the sound transducer system arrangement of the headphones according to the invention, a minimization of the displacement distance of headphone sound transducer systems that is possible here, which enables the front location, is achieved. Broadband, diffuse-field-equalized stereo headphones and / or their sound transducer systems are advantageously used.

With this method, it is advantageous that by means of an exclusive bottom compensation shift of the stereo headphone sound transducer systems against the usually occurring top-in-head localization of hearing events (but excluding front-directional stamping), a "virtual listening event" is realized in its direction cannot be clearly defined.

Furthermore, it is advantageous that, in order to implement a hearing event in the opposite horizontal viewing direction - that is to the rear - a channel swap is made on the left to the right of the two-channel sound event which is equalized in favor of the horizontal front location of hearing events.

It is also advantageous that when using multichannel sound transducer systems to produce better spatial or room acoustics per sounded ear cup, in addition to the headphone / sound transducer systems for the front location of hearing events, a headphone / sound transducer system arrangement opposite to the direction of view behind is chosen below the outer ear anatomy according to claim 16. All four sound transducer systems are controlled separately according to claim 15.

It is also advantageous that the reproduction behavior of the stereo headphone sound transducer systems according to one of claims 19 or 20 is supplemented by acoustic signals with the upper body and head reactions described in detail by BLAUERT and GENUIT, for example a third-wide level increase of 3 dB at approx. 300 Hz . This is particularly advantageous when the stereo headphones according to the invention are in their

This is especially true if the conception, ie its transmission behavior, is rectified especially according to a theoretical signal transmission basis (eg in reflecting rooms). In the event of a deviation from the conventional sound transducer system positions, this is no longer exactly adhered to, so that a sound image adjustment (eg diffuse field equalization) is carried out according to one of claims 19 or 20. The narrow-band distortions generated by the comb filter structures (bandwidth less than one third) and broadband (bandwidth greater than one third) quasi-directional neutral corrections are tonally minimized in the entire listening area (including the use of the masking effect when perceiving sound stimuli of humans).

• Nutzsignal-Störpegelabstand größer 96 dB,
• Dynamik größer 60 dB,
• lineare Verzerrungen (max. Abweichung) kleiner 0,5 dB und
• nichtlineare Verzerrungen kleiner 0,1 %.

It is further advantageous that the modulation of the headphone sound transducer systems by means of an amplifier according to claim 21 with regard to the quality of the electrical transmission behavior meets at least the requirements as follows:

• Useful signal to noise level ratio greater than 96 dB,
• Dynamics greater than 60 dB,
• linear distortions (max. deviation) less than 0.5 dB and
• nonlinear distortions less than 0.1%.

• a) unabhängig vom Tonaufnahmeverfahren (sei es mono- oder stereophon, wie beispielsweise AB-, XY-, Stützpunkt- sowie Kunstkopftechnik) eine horizontale Vorne-Ortung (Bühneneffekt) von Hörereignissen realisiert wird,
• b) die bei der bisherigen Erzeugung einer Vorneortung auftretende Reduzierung der Stereobasisbreite (empfundenes Stereopanorama z.B. von 180 Grad bei normaler Stereokopfhörer-Beschallung mit Oben-Im-Kopf-Lokalisation auf 120 Grad Öffnungswinkel bei vorneortungsermöglichender Kopfhörer-Schallwandlersystemanordnung, ca. zehn Zentimeter in Sichtrichtung vorne, gemäß dem Stand der Technik) erheblich geringer ausffällt (hier größer 160 Grad, da geringere Verschiebungsdistanz),
• c) der Wirkungsgrad der individuellen ortungsverschiebenden Entzerrung vom Kopfhörer-Typ größtenteils unbeeinträchtigt bleibt, wobei u.a. der Frequenzgang und das Schallwandlersystem zu berücksichtigen sind,
• d) Art und Zeitpunkt einer gewünschten Ortungsverschiebung von kopfbezogenen Signalen beliebig bestimmt werden,
• e) aufgrund des mangelnden Wissens bzw. wissenschaftlicher Erörterungen über die Existenz einer der Oben- (-Im-Kopf-) Lokalisation entgegenwirkenden Kompensationsschallwandler- (-Schallereignis-) Verschiebungsrichtung "unten" (siehe oben Literatur), im Zusammenhang mit einer Richtungsprägung "vorne", via Kopfhörer-Beschallung mehrdimensionale, real-räumliche akustische Verhältnisse von z.B. Konzertsälen, unabhängig vom Ursprung des Tonsignals geschaffen werden können, (vgl. Kopfhörer-Quadrophonie: Überwiegend Oben-Im-Kopf-Lokalisation, geringer Anteil der Vorne-Ortung von "vorne-gedachten" Signalen),
• f) mittels einer im Vergleich zur Vorne-Verschiebung bezüglich Verschiebungsdistanz wesentlich überwiegenden Unten-Verschiebung von Kopfhörer-Schallwandlersystemen weit über die Hälfte der bislang für adequate Hörereignisse nötigen Gesamt-Verschiebungsdistanz eingespart wird,
• g) somit sonst übliche erhebliche Baßverluste bei vorne-ortungsermöglichenden Schallwandleranordnungen vor der Ohrmuschel auf einen geringen Wert reduziert werden und nicht zusätzliche u.a. Baß-Schallwandlersysteme direkt an der Ohrmuschel (neben Mitten/Hochton-Schallwandlern) fordern,
• h) eine auf die mittlere Richtcharakteristik des Ohres beruhende Kunstkopf- und/oder Richtungmischpult-Aufnahmetechnik eher zur richtungsgetreuen Abbildung von Schallen führt, da mittels der Wiedergabe-Kompensationsentzerrung "unten" die Im-Kopf-Oben-Lokalisation individuell, aber auch merklich bei einer mittleren Entzerrung, reduziert wird,
• i) somit die von Kunstkopfaufnahmen aufgebaute Richtungsinformation zur Unterscheidung von u.a. "vorne" und "hinten" verstärkt,
• j) deshalb auch die Einführung eines "mittleren" Filters zur gewünschten Beeinflussung der Kopfhörer-Schallortungs-Position Erfolge verspricht (die "mittlere Kompensationsentzerrung liefert im Vergleich eine bessere Vorne-Ortung als eine ausschließlich vom Kunstkopf "vorne" empfangene sowie über Kopfhörer unentzerrt wiedergegebene Schallquelle),
• k) eine erfaßte, geometrische, "mittlere" Anordnung von Schallwandlern eines Stereokopfhörers zugunsten der Hörereignislage horizontal-vorne immer, aufgrund des individuell wirkenden Außenohrreliefs (Vorrausetzung: gehöranatomisch gesunde Personen), eine Wahrnehmung von Schallreizen in Sichtrichtung horizontal-vorne auslöst,
• l) der meßtechnische Aufwand, der für eine elektrische, filtergebundene, kopfbezogene, individuelle Vorne-Entzerrung bislang betrieben wurde (u.a. auch ein teuerer schalltoter bzw. reflexionsarmer Meßraum nötig), nun kostengünstiger ausfällt und
• m) eine außerhalb der üblichen HiFi-Anwendung mögliche Nutzung von vorne-ortungsermöglichenden Stereokopfhörern, z.B. im Zusammenhang mit der Telekommunikation CHör- (Sprecher) und Sehereignis eines vorne befindlichen Monitorbildes stimmen überein), geboten wird.

The advantages which can be achieved with the aid of the invention compared to the prior art are in particular that

• a) regardless of the sound recording process (be it monophonic or stereophonic, such as AB, XY, base and artificial head technology), a horizontal front location (stage effect) of hearing events is realized,
• b) the reduction in the stereo base width that occurred during previous localization (perceived stereo panorama, e.g. from 180 degrees with normal stereo headphone sound with top-in-the-head localization to an opening angle of 120 degrees with a headphone-sound transducer system arrangement that allows for front location, approx. ten centimeters in the viewing direction at the front , according to the state of the art) turns out to be considerably smaller (here greater than 160 degrees, because the displacement distance is smaller),
• c) the efficiency of the individual location-shifting equalization of the headphone type remains largely unaffected, taking into account, among other things, the frequency response and the sound transducer system,
• d) the type and time of a desired location shift of head-related signals are arbitrarily determined,
• e) due to the lack of knowledge or scientific discussions about the existence of a compensation sound transducer (sound event) displacement direction counteracting the top (-in-head) localization "below" (see literature above), in connection with a directional imprint "Front", multi-dimensional, real-spatial acoustic conditions of, for example, concert halls can be created via headphone sound, regardless of the origin of the sound signal (see headphone quadrophony: predominantly top-in-head localization, low proportion of front location) of "front-imagined" signals),
• f) by means of a downward displacement of headphone sound transducer systems, which is predominantly in comparison to the forward displacement with respect to the displacement distance, far more than half of the total displacement distance previously required for adequate hearing events is saved,
• g) thus usual significant Baßverluste be reduced in front localization enabling transducer arrays in front of the auricle to a low value and will not, inter alia, additional bass sound transducers request directly to the pinna (next to the middle / high sound transducers),
• h) an artificial head and / or directional mixer recording technique based on the average directional characteristic of the ear leads more to the directional reproduction of sounds, since by means of the reproduction compensation equalization "below" the head-up localization individually, but also noticeably in one medium equalization, is reduced
• i) thus reinforces the directional information built up by artificial head recordings to differentiate between "front" and "rear",
• j) therefore the introduction of a "middle" filter to influence the desired position of the headphone sound location promises success (the "mean compensation equalization provides a better front location in comparison to a sound source received exclusively from the artificial head" in front "and reproduced undistorted via headphones) ),
• k) a recorded, geometric, "middle" arrangement of sound transducers of a stereo headphone in favor of the hearing event situation always in front horizontally, due to the individually acting outer ear relief (prerequisite: anatomically healthy people), triggers a perception of sound stimuli in the direction of view horizontally-front,
• l) the metrological effort that has so far been carried out for an electrical, filter-bound, head-related, individual front equalization (including an expensive anechoic or low-reflection measuring room is necessary) is now more cost-effective and
• m) a possible use of stereo headphones that allow location to be located outside of the usual hi-fi application, for example in connection with the telecommunication voice (speaker) and visual event of a monitor image at the front match ().

Fig. 1

die Vektoren von in einer vertikalen Ebene befindlichen Schallrichtungskomponenten, welche während des Verschiebungsvorganges der Kopfhörer-Schallwandler eines herkömmlichen Stereokopfhörers in eine Position auftreten, die eine erfindungsgemäße Vorneortung von Hörereignissen gewährleisten,

Fig. 2

einen frequenzabhängigen Differenz-Pegelschrieb {für Proband Nr. 1}, wie er sich bei der Simulation der erfindungsgemäßen Vorne-Ortung ergibt,

Fig. 3

einen frequenzabhängigen Differenz-Pegelschrieb wie in Fig.2 und jedoch für Proband Nr. 2.

The invention will be explained in more detail below with reference to drawings; in these show:

Fig. 1

the vectors of sound direction components located in a vertical plane, which occur during the displacement process of the headphone sound transducers of a conventional stereo headphone into a position which ensure a prior localization of hearing events,

Fig. 2

a frequency-dependent differential level record {for test subject No. 1}, as it results from the simulation of the front location according to the invention,

Fig. 3

a frequency-dependent differential level record as in Fig. 2 and however for subject no. 2.

• a) oben-im-kopf-lokalisierten {d.h. 90 Grad senkrecht bzw. lotrecht "auf der Kopfdecke" befindlichen} sowie
• b) vorne-außer-kopf-lokalisierten {d.h. Null Grad horizontal in Blickrichtung vorne befindlichen} Hörereignissen.

Nachdem ein fließender Übergang zwischen a) und b), insbesondere bei dem bevorstehenden Versuch zur Auffindung des neuen vorneortungsermöglichenden Kopfhörer-Schallwandleraufenthaltsortes, existiert, beispielsweise ein empfundenes Schallereignis in Blickrichtung, 45 Grad Elevationswinkel {in der Medianebene} vor der Stirn, erhält diese zu trainierende Ortungsfähigkeit eine besondere Wichtigkeit. Ziel ist es, daß sich der Proband selbstständig jederzeit mittels der Verschiebung von Kopfhörer-Schallwandlersystemen, üblicherweise während einer angenehm empfundenen musikalischen Beschallung, eine horizontale Vorneortung {nach b)}, realisieren kann.First, the subject, who is exposed to stereo headphones, is explained the essential effects of a hearing event location test typical of the invention. In particular, this includes the exact differentiation and classifiability of ia to be demonstrated by the test management staff

• a) top-in-the-head-localized (ie 90 degrees perpendicular or perpendicular "on the head cover") and
• b) front-out-of-head-localized (ie zero degrees horizontally in front of view) hearing events.

After there is a smooth transition between a) and b), especially in the forthcoming attempt to find the new location for the headphones and transducers, which makes it possible to locate the front location, for example a perceived sound event in the direction of view, 45 degrees elevation angle {in the median plane} in front of the forehead, it is trained Location capability is of particular importance. The aim is that the subject can independently realize a horizontal pre-localization {according to b)} at any time by shifting headphone / sound transducer systems, usually during a pleasantly felt musical sound system.

This is known as the "stage effect" because the subjectively perceived sound event situation is simulated "in front"; for example, there is no real orchestra there.
For this purpose, any sound preserves that have been recorded using intensity-stereophonic technology are recommended. Artificial head music production is unsuitable because it may not be possible to find a clear top-in-head localization via stereo headphones.
Before the test person builds up the "stage effect", ie the horizontal pre-location, a schematic overview of the procedure should be presented in advance: Figure 1 shows, using vectorial representation in the median level, component 1 of the sound source location with unchanged, ie manufacturer-specific attached stereo headphone transducer systems {5 indicates the outline of a headphone capsule}. This location corresponds to the top-in-the-head localization 1 of hearing events with stereophonic headphone sound. A second vector 2 forms the UP COMPENSATION direction "down" when the stereo headphone sound transducer systems are shifted. This eliminates the top-in-head sound source location component 1. Vector 3 represents the IMPRESSION of the auditory event directional perception “in front”, that is to say the “stage effect”. The stereo headphones {in outline representation of the headphone capsule 5} located on the outer ear 4 according to the manufacturer are placed in a position enabling the auditory event to be located at the front brought {see element 6 of Fig.1}. In addition, the headphone sound transducer systems 6. Towards the outer ear 4 are at an angle of, for example 30 degrees inclined for an upgrade of the acoustic efficiency {acc. the perspective isometric representation of the outlines of a headphone sound transducer system 6}. The direction of sound propagation is represented by the vectors 7.

• a) nach dem "offenen" Prinzip sowie
• b) ohrumschließend arbeiten,
• c) über einen verstellbaren Kopfbügel sowie
• d) über mehrachsig verstellbare Schallwandler verfügen und
• e) deren Schallwandlersysteme {je Kanal} eher einer Punktschallquelle entsprechen. Breitflächenstrahler mit z.B. Abmessungen von 100 X 100 Millimeter sind {ausschließlich} im Rahmen der Ortungstests ungeeignet.

These processes, which are dealt with schematically in theory, according to FIG. 1, must then be put into practice. It is important that the test person is sounded through headphones again, for example musically "stereo". Those common models are particularly suitable as test headphones:

• a) according to the "open" principle as well
• b) working around the ear,
• c) via an adjustable headband and
• d) have multi-axis adjustable transducers and
• e) whose sound converter systems {per channel} correspond more to a point sound source. Wide area radiators with dimensions of 100 X 100 millimeters, for example, are unsuitable for the location tests.

• a) eine geringfügige Sicherungsverschiebung nach unten um ca. einen Millimeter angefügt und
• b) zur Verbesserung des Gehörgangsbeschallungswirkungsgrades beide Kopfhörer-Schallwandlersysteme winkelig zur/zum Ohrmuschel/Ohrkanal hin angeordnet {ca. 20 bis 40 Grad Azimut- und Elevationswinkel in der Horizontal- sowie Medianebene}. Falls sich dabei die empfundene Hörereignislage ungünstig verändert,
  wird bei winkelig gehaltenen Kopfhörer-Schallwandlersystemen nochmals eine korrigierende Fein-Nachverschiebung {siehe oben ab "empirischer, abwägender Verschiebungsvorgang"} getätigt.

Beispielsweise ergibt sich mit einem handelsüblichen {offenen, ohrumschließenden) Kopfhörer-Modell, der, je Kopfhörer-Kapsel, über einen kreisrunden Schallwandler {Durchmesser zirka 30 Millimeter} verfügt, eine Endverschiebungsdistanz lotrecht nach unten von 45 Millimeter und in Sichtrichtung nach vorne von 15 Millimeter {mit Azimut/Elivation von 35 Grad}. Zum anderen verringern sich diese Zahlenwerte der Endverschiebungsdistanzen ungefähr um 50 % bei Verwendung ohraufliegender Walkman-Kopfhörer-Modelle. Als Referenzpunkt dient hier der Ohrkanal, vor dem sich mittig angeordnet normalerweise eine herstellergerecht aufgesetzte Kopfhörer-Kapsel befindet. Dies entspricht bei Probandenversuchen einem gängigen Verhältnis von 3:1 {Gegenüberstellung der Unten- mit Vorne- Verschiebungsdistanz}.
Im Bezug auf eine alternative mehrkanalige Außenohr-Beschallung ist, neben dem vorne-unten {je Ohrmuschel} plazierten, vorneortungsermöglichenden Schallwandlersystem {Austernerung mit direktem bzw. unbearbeitem Tonsignal}, ein sekundäres Schallwandlersystem {Austeuerung mit Raumreflexionsmustern},
das im Normalfall herstellergerecht vor der Ohrmuschel angeornet wird, ausgehend vom Referenzpunkt Ohrkanal, gegen die Sichtrichtung nach hinten-unten zu verschieben und schließlich zu plazieren. Hinsichtlich der Auffindung des hierfür geeigneten Schallwandleraufenthaltsortes werden die oben genannten Verfahrenschritte vollzogen. In diesem Zusammenhang wird eine minimale Verschiebungsdistanz mit maximalem Effekt gesucht, welche bei Austeuerung solcher hinten-unten plazierter Schallwandlersysteme mit stereophonen Tonsignal "virtuelle" {Begriff: siehe Seite 1 ff.} Hörereignisse mit leichter hinten-anteiliger Ortung erzeugen. Hinweis: Eine generelle Hinten-Unten-Anordnung von Schallwandlersystemen zur Hintenortung von Hörereignissen bei stereophoner Kopfhörer-Beschallung ist aufgrund der Außenohr-Formgebung {"anatomisches" richtungsabhängiges Filter} mit größeren Verschiebungsdistanzen, im Verhältnis zu Vorne-Unten-Anordnung von Schallwandlersystemen, zu aufwendig und somit weniger praktikabel.
Werden schließlich die vorne-unten [I] und hinten-unten [II] plazierten Schallwandlersysteme mit den ursprünglich vorgesehenen Tonsignalen {direktes Tonsignal für [I] und Raumreflexionsmuster für [II]} Aussteuerung, dann wird, ein nochmals verbreitertes, dreidimensionalräumlich aufgewertetes Hörereignis geboten.For the ambitious goal "horizontal front localization" of auditory events is disputed following itterativer operation:
First, the stereo headphones are put on according to the manufacturer's instructions and then the signal is controlled by the acoustic transducers. Then both headphone transducer systems are lifted with both hands approximately as far from the head cover / temple side {approx. 5 to 10 millimeters} that the headphone pads just over the ear cups are touchable. Then, paying attention to the spatial position of the hearing event, the headphone sound transducer systems are moved in increments of less than 5 millimeters, depending on the front {in the direction of view} and downwards {perpendicular in the shoulder direction}.
After generally a good 15 millimeters of two-dimensional displacement distance, there is a striking hearing event location shift (elimination angle in the median plane of, for example, 30 degrees in front), which now causes a specific stereo headphone to be made no longer alternately, but depending on the individual case of the hearing event location change. Displacement process is realized. In the example of 30 degrees elevation angle just mentioned, a sufficient front embossing of the hearing event can already be assumed, which is why a additional compensation shift down a few millimeters is recommended {directed towards the top-in-the-head localization component}. If this shift causes a hearing event situation that does not yet correspond to the horizontal pre-localization, the downward shift just undertaken is halved in its selected millimeter distance, ie reduced to half. Then, by means of further reduced displacement steps, equally in an empirical manner, the "stage effect" sought is optimized by adding or subtracting. In this example, a shift of one to two millimeters to the front is selected, then the further, empirical, weighing shift process. When the new location of the stereo headphones, which enables location, is finally found

• a) added a slight downward shift of the fuse by approx. one millimeter and
• b) to improve the auditory canal sound efficiency, both headphone transducer systems are arranged at an angle to / towards the auricle / ear canal {approx. 20 to 40 degrees azimuth and elevation angles in the horizontal and median plane}. If the perceived hearing event situation changes unfavorably,
  If the headphone / sound transducer system is held at an angle, a corrective fine shift is made again {see above from "empirical, weighing shifting process"}.

For example, with a commercially available {open, circumaural) headphone model, which, for each headphone capsule, has a circular sound transducer {diameter approx. 30 millimeters}, an end displacement distance vertically downwards of 45 millimeters and in the direction of view forward of 15 millimeters {with azimuth / elimination of 35 degrees}. On the other hand, these numerical values of the end shift distances are reduced by approximately 50% when using the Walkman headphone models on the ear. The ear canal serves as a reference point , in front of which there is normally a headphone capsule that is placed in the center of the manufacturer. In test subjects, this corresponds to a common ratio of 3: 1 {comparison of the bottom and front displacement distances}.
With regard to an alternative multi-channel external ear sound system, next to the front-bottom {per auricle} placed, front location-enabling sound transducer system {Oysterization with direct or unprocessed sound signal}, a secondary sound transducer system {leveling with room reflection patterns},
which is usually arranged according to the manufacturer in front of the auricle, starting from the ear canal reference point , to be moved backwards and downwards against the viewing direction and finally to be placed. With regard to the location of the sound transducer location suitable for this, the above-mentioned process steps are carried out. In this context, a minimum displacement distance with a maximum effect is sought, which when such rear transducer systems placed behind and below are activated with stereophonic sound signal "virtual" {term: see page 1 ff.} Generate hearing events with a slight rear-based location. Note: A general rear-bottom arrangement of sound transducer systems for the rear location of hearing events with stereophonic headphone sound is too complex due to the outer ear shape {"anatomical" direction-dependent filter} with larger displacement distances, in relation to the front-bottom arrangement of sound transducer systems and therefore less practical.
Finally, if the front-bottom [I] and rear-bottom [II] sound transducer systems with the originally intended sound signals {direct sound signal for [I] and room reflection pattern for [II]} modulation, then a further broadened, three-dimensionally enhanced listening event is offered .

This location of stereo headphone sound transducer systems, which enables location at the front, is maintained until the end of the collection of data in the form of the arrangement geometry or an outer ear transmission dimension.

Measurement of linear distortion in headphone shift

In order to simulate a pre-location that is independent of the directional shift, a frequency-dependent difference level formation is used, from which, according to the invention, the necessary front-directional, additional, additional pre-equalization of stereo headphone / sound converter systems is determined as follows: First, suitable, ie non-distorting {dynamics greater than 58 dB , Harmonic distortion less than 0.1%, frequency response from 20 Hz to 20 kHz} or probes that do not hurt, frequency response-corrected probes} miniature microphone capsules, which take acoustic signal samples from the ear canal or ear canal via a tube-like sound supply system, implanted approx. 4 millimeters inside the ear canal .
For a later digital signal processing, so-called "digital microphones" {known in the recording studio level} would be more useful. Suitable types are not yet available.

The {analog} alternating electrical signal generated by the miniature microphone {approx. 10 millivolts} is usually amplified to a voltage level greater than 0.5 volts {technical data on amplifier quality, according to the microphone}, so that later used analogue-digital converters that process this signal, before the actual IT systems, do not work in a quantization range and therefore would have an insufficient resolution or sound signal scanning quality.

• a) vermag das Außenohrrelief aufgrund seiner Abmessungen nur oberhalb einer Frequenz von ca. 1 kHz als akustischer Dämpfer und Resonator zu dienen, und
• b) zeigt der kontinuierliche Frequenzgangabfall zu Baßpartien hin den reduzierten Wirkungsgrad von "offenen" Schallwandlersystemen bei nicht am Außenohr herstellergerecht befindlichen {aufgesetzten} Stereokopfhörern.

Deshalb wurde dieser untere Frequenzgangbereich mittels Hörtests zur Verbesserung einer tonsignal-breitbandigen horizontalen Vorneortung von Hörereignissen nochmals dahingehend untersucht, ob dieser durch additive Pegelanhebungen {z.B. terzbreit + 3 dB bei 300 Hz} und/oder -absenkungen effektiv ergänzt werden soll.
Im Vergleich zu anderen Differenzpegelschrieben kristallisierte sich hier insbesondere der relative Frequenzgangabfall unterhalb 1,8 kHz, die Senke im Bereich von 5 bis 8 kHz, die Anhebungen zwischen 1,5 und 5 kHz, um 8,5 kHz sowie gemittelt oberhalb von 12 kHz heraus. Die markanten Punkte im Frequenzgang können um einige hundert Hertz frequenzmäßig streuen. Desweiteren ist vereinzelt eine ca. terzbreite relative Anhebung (1 bis 3 dB) unter 500 Herz festzustellen.
Der markante Baßeinbruch von minus 10 dB gegenüber dem kontinuierlichen Frequenzgangabfall zu tiefen Frequenzen hin {ca. 5 dB im Vergleich zum 1 kHz-Pegelwert} wurde durch einen Fehler bei der Messungsdurchführung erzeugt.The sinus sweep from 20 Hz to 20 kHz is selected from the multitude of measurement methods {see pages 1 ff.}, Since the process is based on an immediate disclosure of the outer ear-headphone-sound converter response in the form of frequency-dependent level fluctuations. A sound level of typically less than 75 dBSPL is selected.
A subsequent difference level formation, from the {representative} frequency response graphics "headphones normal" {manufacturer-appropriate on the ear cup} and "position-varied", ie level values from the second minus the first-mentioned graphic, corresponds, for example, to the curve shown in FIG. 2, with an outer ear of an individual person {with a tendency towards "medium" directional characteristics}:
Two broadband 4 dB boosts around 1.8 kHz, 3.6 kHz and a broadband 18 dB deep dip between 5 kHz and 8 kHz are particularly noticeable. Secondary are narrow-band resonances around 4.8 kHz {max. Level 5.5 dB}, around 8.5 kHz {max. Level 3 dB} and a dip at 11 kHz {min. Level minus 7 dB}. From approx. 12 kHz, resonance and sinks alternate like a comb filter in a rhythm of approximately 2 kHz.
The shown, for an individual person {no. 1} The measured difference level-frequency response curve no longer contains any level unevenness relevant for the headphone-generated front location below the frequency of 1 kHz. This is correct and has general validity, because

• a) due to its dimensions, the outer ear relief can only serve as an acoustic damper and resonator above a frequency of approximately 1 kHz, and
• b) the continuous drop in frequency response towards the bass shows the reduced efficiency of "open" sound transducer systems in stereo headphones that are not attached to the manufacturer's ear.

For this reason, this lower frequency response range was examined again using hearing tests to improve a broadband horizontal pre-localization of hearing events to determine whether this should be effectively supplemented by additive level increases {e.g. third-width + 3 dB at 300 Hz} and / or reductions.
In comparison to other differential level recordings, the relative frequency response drop below 1.8 kHz, the dip in the range from 5 to 8 kHz, the increases between 1.5 and 5 kHz, around 8.5 kHz and averaged above 12 kHz crystallized here . The striking points in the frequency response can spread in frequency by several hundred Hertz. Furthermore, an approximate third-octave relative increase (1 to 3 dB) below 500 hearts can be determined.
The striking bass dip of minus 10 dB compared to the continuous drop in frequency response towards low frequencies {approx. 5 dB compared to the 1 kHz level} was generated by an error in the measurement.

This is shown in FIG. 3, which represents a further detection of linear distortions in the case of a sound transducer arrangement of a stereo headphone that allows for front location. Another, arbitrarily selected {second} subject was available for the measurements according to FIG. 3. Despite the different outer ear anatomy of subjects I and II, there is a high correlation in the essentially frequency range between the two difference level graphs {cf. Fig. 2 with Fig. 3}, which the level increase at the frequencies below 2 kHz, 4 kHz and 8 kHz as well as the attenuation dips around the frequencies 6 kHz and 11 kHz prove. Likewise, in FIG. 3, a frequency response drop towards low frequencies that is known from FIG. 2 and runs continuously in a similar manner can be determined.

Claims (21)

1. Stereo headphone with a disposition of the sound transducers thereof, which, starting from the conventional disposition at the external ear relief, are shifted forwards in the direction of sight by a predetermined amount, characterized in that the sound transducers additionally are shifted downwards in the direction of sight by an amount exceeding the horizontal amount and being adequate for transforming the above-in-the-head localization into an essentially horizontal frontally localized auditory event.
2. Stereo headphone according to claim 1, characterized by a variable geometry of disposition of its sound transducers in favour of either

   a) a position of the auditory event above-in-the-head with a conventional disposition of the sound transducers or

   b) the position of the auditory event horizontal in front.
3. Method for optimizing the disposition of the sound transducers of a stereo headphone, wherein by means of shifting both sound transducers, a perferred auditory event is determinated in an empirically optimizing matter by starting from the reference position of the conventional disposition of the sound transducers at the external ear relief of a test subject forwards in the direction of sight, characterized in that transducers for optimizing the disposition of the sound transducers of the stereo headphone for the horizontal in-front localization of auditory events in accordance with claim 1 or 2 the sound transducers additionally are shifted by an amount downwards exceeding the horizontal amount by iteratively shifting the sound transducers alternatingly downwards and forwards in steps of a given width.
4. Method according to claim 3, characterized by a step width of less than 5 millimetres.
5. Method according to claim 3 or 4, characterized in that the sound transducers of the stereo headphone are inclined by angularly directing them to the auditory canal of the ear in order to increase the effectivity of sound irradiation at the external ear relief and/or to optimize the positionability of the sound transducers at the external ear relief.
6. Method according to claim 3 or 4, characterized in that the iterative determination of the optimal disposition of the sound transducers is separately conducted at the left and the right ear of the test subject, respectively.
7. Method according to claim 6, characterized in that the determination of the optimal disposition of the sound transducers is conducted by means of any stereo audio signal multiply varying during the determination process.
8. Method according to one of claims 3 to 7, characterized in that the optimal disposition of the sound transducers is determined by at least four shifting procedures which in each case are to be repeated anew.
9. Method according to claim 8, characterized in that that one of the at least four shifting procedures which possesses the majority of the typical characteristics of the other ones is selected in order to determine the optimal disposition of the sound converters.
10. Method according to claim 9, characterized in that the shifting procedures are performed on a plural number test subjects.
11. Method according to claim 10, characterized in that at least eight arbitrarily selected persons who are healthy concerning their organs of hearing are used for determining the optimal disposition of the sound transducers.
12. Method according to claim 11, characterized by averaging the individual results.
13. Method according to one of claims 3 to 12, characterized in that the optimal disposition of the sound transducers with respect to the angle of inclination of the sound transducers, and the shift distance in the downward and forward direction, based on the three-dimensional spatial position of stereo headphone worn at the external ear in a manner recommended by the manufacturer, is determined within an accuracy of millimetres.
14. Stereo headphone according to claim 2 or according to the method according to one of claims 3 to 13, characterized in that a disposition geometry of the sound transducers of the stereo headphone which is optimized and/or minimized with respect to the shifting distance, which is chosen in favour of an auditory event horizontal in front, starting from the conventional disposition geometry of the sound transducers in favour of the auditory event above-in-the-head with a relation of the shifting distances downwards to forwards preferably greater than two to one.
15. Method according to one of claims 3 to 14, characterized in that in favour of generating multi-dimensional spatial acoustic auditory events the sound transducers are fed in favour of the auditory event horizontal in-front with a stereophonic audio signal of an audio source and the disposition of the sound transducers thereof being chosen in favour of the auditory event above-in-the-head with stereophonic spatial reflections derived from the stereophonic audio signal of said audio source.
16. Method according to claim 15, characterized in that the disposition of the sound transducers, for spreading the multi-dimensional spatial auditory event by means of multi-channel stereo headphone in favour of an above-in-head localization, is varied by shifting it in conformity with the disposition of the sound transducers in favour of the auditory event horizontal in-front by an adequate amount downwards and/or opposed to the direction of sight rearwards.
17. Method according to one of claims 3 to 16, characterized in that preferably for comparison of auditory events and/or for measurement purposes a freely selectable switching is provided between the sound transducers in order to produce auditory events favouring the above-in-the-head/in-front localization and multi-dimensional spatial acoustics characteristics.
18. Method according to claim 17, characterized in that conventionally used headphone pads for centering of headphone boxes and/or stereo headphones at the and/or in front of the auricle being preferably supplemented by materials permitting the passage of sound and being elastically stressable, in order to realize a disposition of the sound transducers of stereo headphone in favour of the auditory event horizontal in-front and/or above-in-the-head independently of the stay position.
19. Method according to the one of claims 3 to 18, characterized in that in favour of providing sound neutral auditory events the bass and the middle transmission ranges are influenced by means of a coupling between the head and the headphone's earpads and/or the headphone's box construction and/or a correction of the reproduction frequency response of the sound transducers.
20. Method according to one of claims 3 to 19, characterized by a preferably - compared to the linear and comb-filterlike distortions occuring in the generation of the horizontal in-front localization of auditory events - relatively broadband correction favouring sound neutrality in the upper middle and/or top transmission ranges of the sound transducers in stereo headphones.
21. Method according to claims 3 to 19, characterized in that the sound transducers are level set by means of a technically high-grade separate multichannel amplification of the audio signal setting the level of the sound transducers, which amplification is made to be controllable.

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