DE102022004259B3 - Surround sound headphones based on large-area planar sound transducers - Google Patents

Abstract

The invention relates to headphones with a left and a right headphone capsule, in each of which a large-area planar sound transducer (10) with a sound-emitting membrane (11) is accommodated. It is provided that, in order to facilitate pre-localization of auditory events, a sound reflector (15) is arranged on the outside of the planar sound transducer (10) facing away from the respective auricle (13) of a headphone user in a lower edge zone (lower area) (14) and, depending on requirements according to the headphone construction principle, a supplementary sound reflector (15a) is arranged in the central area of the planar sound transducer (10) facing away from the auricle, expanding the area to (15).

Description

The invention relates to a surround sound headphone with a left and a right headphone capsule, in each of which a large-area planar sound transducer with a sound-emitting membrane is accommodated.

It is known that the two planar sound transducers of these headphones can be designed with an electrostatic or magnetostatic drive. The membranes of these sound transducers are large and extremely thin and low-mass in the form of thin foils in order to achieve practical efficiency. The low mass of the membranes, which are only a few micrometers thick, has the advantage over electrodynamic and electromagnetic drives with relatively massive membranes that a frequency range of well beyond the audibility limit of around 20 kHz can be achieved.

Furthermore, the almost inertia-free reaction of the membrane makes the sound transducer extraordinarily impulse-fidelity, which benefits the high resolution and spatial information of the sound signal.

Furthermore, the isoplanar vibration behavior of the membrane offers a minimum of partial vibrations and thus, with optimal design, contributes to a particularly unadulterated and clear sound result that was previously not achievable with headphone concepts equipped with electrodynamically driven sound transducers.

However, due to the relatively small surface area of the transducer membrane with electrodynamic drive, stereo headphones equipped with it are able to modify the unpleasant, pronounced in-head localization of binaural sound events with a conventional central arrangement of the transducers essentially centrally in front of the auditory entrance of the user's ear in favor of a forward localization of sound events by arranging the transducers from the front and bottom starting from the central arrangement mentioned, as for example in the EP 0 484 354 B1 , DE 42 37 710 A1 , DE 195 14 105 A1 and DE 100 61 837 A1 The basis for the pre-localization of sound events generated in this way is the targeted use of individual direction-specific distortions of the pinna (auricle), which acts as a directional filter and is caused by the sound being dampened and reflected at the relief edges of the auricle depending on the frequency and thus being transmitted to the ear canal in different intensity-related ways depending on its frequency components.

The auricle, for example, shades or dampens sound coming from behind. This allows the brain of an individual headphone user, etc., to draw on habitual directional information (see Head-Related Transfer Functions) that has been trained since early childhood about the 3D spatial origin of sound sources or psychoacoustically described auditory events, in particular whether a sound stimulus or sound event arrives at the auricle from the front, above or behind and with more or less elevation (relative to the horizontal plane).

This well-known and effective measure for providing the ability to localise the sound in the horizontal plane using headphones cannot be implemented with large-area planar sound transducers. The reason for this is that these sound transducers emit sound uniformly across the entire large surface of the pinna of the user's ears, thereby creating unnatural linear near-field sound distortions that are counterproductive to neutral and clear stereo sound reproduction. In addition, insufficient or even counterproductive noise reduction is used for out-of-head localisation or

Pre-localization of auditory events produces significant, individual direction-specific distortions of the pinna.

A headphone with the features of the preamble of claim 1 is known from US 2015 / 0 326 974 A1 In this headphone, the magnetic north and south poles and sound passage gaps, which are spaced apart to form sound passage gaps, run vertically with respect to the line of sight of the headphone user.

There is a need to achieve user-individual frontal localization of auditory events even with headphones based on large-area planar sound transducers.

An object of the present invention is therefore to take measures to provide a forward localization of sound events using headphones based on large-area planar sound transducers.

This object is achieved by the features of claim 1. Advantageous developments of the invention are set out in the subclaims.

The subject of the invention is therefore a headphone with a left and a right headphone capsule, in each of which a large-area planar Sound transducer with a sound-radiating membrane, whereby a sound reflector is arranged in a central and primarily lower edge zone on the outside of the planar sound transducer facing away from the respective auricle of a headphone user in order to facilitate pre-localization of auditory events.

This surprisingly enables essentially horizontal front localization with minimized elevation of auditory events using headphones based on large-area planar sound transducers, which can ensure front localization of sound events.

One possible explanation for the ability to localize sound events using the design measure according to the invention is that the increased high-frequency sound radiation of the large-area membrane, which is achieved by sound reflection, starting from its lower or lower-front edge zone, shifts the original in-head localization of auditory events downwards or lower-front, whereby this sound radiation with a focus essentially at the bottom manifests itself in a forward localization of sound events due to the large-area structure of the auricle being exposed to sound. In other words, the decentralized rear, especially high-frequency reflection stimulates part of the large-area membrane in a decentralized manner, primarily at the bottom, and feeds it to the auricle, which stimulates a kind of simulation of free sound wave incidence at the bottom and/or lower-front.

• - der Schallreflektor sich vorteilhafterweise parallel zur Sichtrichtung des Kopfhörer- Nutzers erstreckt,
• - auf der jeweiligen Ohrmuschel eines Kopfhörer-Nutzers zugewandten Innenseite des jeweiligen Planar-Schallwandlers in einer mittig-oberen Randzone vorteilhafterweise ein parallel zur Sichtrichtung des Kopfhörer-Nutzers verlaufendes ausgebildetes, frequenz-pegelbezogen geringfügig schalldämpfendes Element angeordnet ist,
• - das schalldämpfende Element sich vorteilhafterweise parallel zur Sichtrichtung des Kopfhörer-Nutzers erstreckt,
• - das schalldämpfende Element zur Dämpfung hoher Tonsignal-Frequenzen, vor allem von 1,5 kHz bis 20 kHz, bevorzugt von 3 kHz bis 10 kHz vorteilhafterweise ausgelegt ist,
• - ohrmuschel-zugewandt und - abgewandt eine obere Randzone sowie untere Randzone ohrmuschel-zugewandt, also jeweils die Vorder- und Rückseite des Planar-Schallwandlers dort vorteilhafterweise ungedämpft akustisch durchlässig ist,
• - in einer zentralen Zone zwischen der oberen Randzone und der unteren Randzone des Planar-Schallwandlers vorteilhafterweise ohrmuschel-zugewandt ein schalldämpfendes Element angeordnet ist, das mittige sowie hohe Tonsignal-Frequenzen bedämpft, für tiefere Tonsignal-Frequenzen jedoch durchlässig ist.
• - Insbesondere ist ohrmuschel-abgewandt neben dem vorteilhaften Schallreflektor in der unteren Randzone, je nach Kopfhörer-Bauart sowie Kopfhörer-Ohrpolstergestaltung (siehe Ohrpolsterumrandung offen bis hin zu geschlossen bzw. schalldurchlässig ab den Hoch-Bassaudiosignalbereich oder eben unteren Mitten bis in den obersten Hörfrequenzbereich), ein weiterer Ergänzungs-Schallreflektor mittig am Planar-Schallwandler ohrmuschel-abgewandt angebracht; oder in anderen Worten: Es erstreckt sich jener Schallreflektor im unteren Randbereich erweitert bis hin in den mittigen Bereich vor dem besagten Planar-Schallwandler.

Based on these acousto-mechanical basic findings, the extent of the forward localization of sound events can also be individually adjusted or modified to optimize the

• - the sound reflector advantageously extends parallel to the line of sight of the headphone user,
• - on the inner side of the respective planar sound transducer facing the respective ear cup of a headphone user, in a central upper edge zone, there is advantageously arranged a formed, slightly sound-damping element running parallel to the line of sight of the headphone user,
• - the sound-absorbing element advantageously extends parallel to the line of sight of the headphone user,
• - the sound-damping element is advantageously designed to dampen high sound signal frequencies, especially from 1.5 kHz to 20 kHz, preferably from 3 kHz to 10 kHz,
• - facing the auricle and - facing away from it an upper edge zone and a lower edge zone facing the auricle, i.e. the front and back of the planar sound transducer are advantageously acoustically permeable without damping,
• - in a central zone between the upper edge zone and the lower edge zone of the planar sound transducer, a sound-damping element is advantageously arranged facing the auricle, which dampens central and high sound signal frequencies, but is permeable to lower sound signal frequencies.
• - In particular, in addition to the advantageous sound reflector in the lower edge zone, depending on the headphone design and headphone ear pad design (see ear pad border open to closed or sound-permeable from the high bass audio signal range or lower mids to the highest audible frequency range), another supplementary sound reflector is attached in the middle of the planar sound transducer facing away from the auricle; or in other words: the sound reflector in the lower edge area extends into the middle area in front of the planar sound transducer in question.

In the case of a magnetostatically driven planar sound transducer with a membrane that is surrounded on both sides by strip-shaped, parallel magnetic north and south poles that are spaced apart to form sound passage gaps, the magnetic north and south poles and sound passage gaps are advantageously aligned so as to run diagonally from back to front with respect to the line of sight of the headphone user. The diagonal alignment of the magnetic north and south poles and sound passage gaps preferably includes an angle of 10 to 60 degrees, especially 20 to 45 degrees.

• 1 schematisch eine Draufsicht eines Planarschallwandlers des erfindungsgemäßen Kopfhörers sowie rechts daneben eine Seitenansicht des Planarschallwandlers in seiner Nutzungsposition vor der Ohrmuschel eines Kopfhörer-Nutzers, und
• 2 die Draufsicht des Planarschallwandlers von 1 in einer um einer bezüglich seinem Normalenvektor gedrehten Nutzungsposition.

The invention is explained in more detail below with reference to the drawing. In this drawing:

• 1 schematically a top view of a planar sound transducer of the headphones according to the invention and, to the right of it, a side view of the planar sound transducer in its use position in front of the auricle of a headphone user, and
• 2 the top view of the planar transducer of 1 in a usage position rotated with respect to its normal vector.

Like every pair of headphones with a left and a right headphone capsule, the headphones to be explained here also contain a sound transducer in each headphone capsule. This sound transducer is a large-area planar sound transducer 10 with a sound-emitting membrane 11. The planar sound transducer 10 is designed as a magnetostat, i.e. its membrane, which is only a few micrometers thick and therefore extremely low in mass, is driven electromagnetically. This drive comprises magnetic strips that run parallel to one another, are spaced apart from one another and enclose the membrane 11 at a distance on both sides, of which a pair of magnetic strips N,N or S,S on both sides of the membrane 11 have the same polarity (north or south pole), with the successively arranged pairs of magnetic strips N,N and S,S alternating between one and the other polarity. The membrane 11 is coated with an electrically conductive material and is connected to an audio signal source which causes the membrane to vibrate and emit sound following the audio signal due to its arrangement between the magnetic strip pairs N,N and S,S.

The membrane 11 is clamped in a frame-shaped holder 12, which also functions as a carrier for the magnetic strip pairs N,N, and S,S.

In a lower area 14 shown in dashed lines, a sound reflector 15 is arranged on the outside of the planar sound transducer 10 in its lower edge zone, facing away from the respective auricle 13 of a headphone user; the sound reflector 15 is likewise supplemented or extended by a supplementary sound reflector 15a that is identical to the sound reflector 15, depending on the headphone design (compare open/closed or sound-impermeable or sound-permeable; ear pad design, etc.). The sound reflector 15 comprises an acoustically hard and therefore reflective film or continuous plastic wall (see sound reflector 15 and/or supplementary sound reflector 15a), through which the sound radiation from the area of the membrane 11 located in front of this film and/or plastic wall is amplified by reflection on the sound reflector. The extent to which an acoustically "hard" sound reflector is arranged in a reduced area in area 14 and/or 20 or whether a surface-extended "hard" supplementary sound reflector is also provided in the central area 15a facing away from the auricle to optimize the surround sound image relates to the acoustic design of the respective headphones as a rather open, partially closed or closed designed surround sound headphone; see also ear pad variants or headphone housings (or headphone capsules) such as closed or sound-impermeable in the bass range as well as sound-permeable ear pad variants either in the lower mid-frequency range up to the highest audible frequency range, which specify this in an influencing manner (cf. only area 15 and/or 15a designed as a sound reflector). This reflected sound component, which is amplified in total with the direct sound, interacts with the opposite area of the auricle (as a direction-specific, frequency-dependent filter relief) to produce a planar sound wave that enters the auditory canal 16 from below upwards (not radiating vertically at 90 degrees but at an angle other than 90 degrees) and causes a near-field sound direction change in the ear in favor of a horizontal pre-localization of auditory events.

Furthermore, in the dashed area 14 on the outside of the planar sound transducer 10 facing the respective auricle 13 of a headphone user (immediately in front of the ear canal 16), a damping element 17 is arranged, which comprises a fleece a few tenths of a millimeter thick that has a maximum slight or no damping effect, is "quasi open" to the bass and treble radiation of the membrane 11 and dampens medium frequency components (around approximately 500 Hz to 3 kHz) of the emitted sound to a very small extent in order to provide a sound transmission behavior that provides additive high frequency generation around 3 to at least 20 kHz in front of the ear lobe 18 of the auricle 13, thereby optimizing the forward localization.

An upper region 19 of the planar sound transducer 10, shown in dashed lines, is acoustically completely open on both sides of this transducer over the entire audio signal frequency range in order to primarily ensure unhindered sound radiation or acoustic wave passage of the membrane 11 towards the ear / auricle over the entire audio/frequency range.

In summary, a central region 20 of the planar sound transducer 10, shown in dashed lines, adjacent to the lower region 14 and the upper region 19 on both sides of this transducer is either acoustically "hard" reflective or impermeable or, alternatively, directed towards the auricle 13, acoustically either partially permeable and/or slightly dampened by means of applied damping material in the lower to medium frequency range (approximately in the low-mid range up to 10 kHz or preferably up to 3 kHz).

As in 2 shown, the magnetic strip pairs N,N, and S,S of the electrostatic drive of the planar sound transducer 10 and the sound passage gaps 21 left free between them are with reference to the viewing direction of the headphone groove zers is advantageously aligned so as to rise diagonally from back to front. Preferably, the diagonal alignment of the magnetic strip pairs N,N, and S,S and sound passage gaps 21 includes an angle of rise or rotation 20 (or α) of 10 to 60 degrees, especially of 20 to 45 degrees.

List of reference symbols

10

Planar transducer

11

membrane

12

bracket

13

auricle

14

lower area

15

Sound reflector

15a

Additional sound reflector

16

ear canal

17

Damping element

18

Earlobes

19

upper area

20

central area

21

Sound passage gaps

22

Angle of rise or rotation α

Claims (9)

Headphones with a left and a right headphone capsule, in each of which a magnetostatically driven large-area planar sound transducer (10) with a sound-emitting membrane (11) is accommodated, wherein the membrane (11) is enclosed on both sides by strip-shaped, parallel magnetic north and south poles (NN, SS) which are spaced from one another to form sound passage gaps (21), characterized in that a sound reflector (15) is arranged in a lower edge zone (lower region) (14) on the outside of the planar sound transducer (10) facing away from the respective auricle (13) of a headphone user, and the magnetic north and south poles and sound passage gaps (21) are aligned so as to rise diagonally (22) from back to front with reference to the direction of vision of the headphone user. Headphones after Claim 1 , wherein the sound reflector (15) extends parallel to the line of sight of the headphone user. Headphones after Claim 1 or 2 , wherein on an inner side of the respective planar sound transducer (10) facing the respective auricle (13) of a headphone user, an acoustically slight or slightly sound-damping element (17) is arranged in a central edge zone (middle region) running parallel to the line of sight of the headphone user. Headphones after Claim 3 , wherein the sound-damping element (17) extends parallel to the line of sight of the headphone user. Headphones after Claim 3 or 4 , wherein the sound-damping element is designed to dampen essentially medium sound signal frequencies, in particular from approximately 300 Hz to 10 kHz, preferably from 500 kHz to 3 kHz. Headphones after one of the Claims 3 until 5 , whereby an off-center zone (area facing towards/away from the auricle and area opposite the auricle) between the upper edge zone and the lower edge zone of the front and back of the planar sound transducer is acoustically permeable without damping. Headphones after Claim 6 , whereby the oblique alignment of the magnetic north and south poles (NN, SS) and sound passage gaps (21) creates an angle of rise (22) of 10 to 60 degrees, especially of 20 to 45 degrees. Headphones after one of the Claims 1 until 7 , whereby the headphone capsule is acoustically open on the side facing away from the ear of the headphone user. Headphones after one of the Claims 1 until 7 , wherein the headphone capsule and/or ear pad border of the auricle (13) is acoustically closed, apart from the side facing the ear of the headphone user, in particular for the audio frequency range below 1 kHz and in particular below 300 Hz.

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