Headphones with automatic volume limiter

Abstract

In certain cases, volume limiting circuits are required for audio playback devices. In conjunction with wireless headphones, this can unnecessarily reduce the maximum reproducible volume. According to the invention, a volume limit in wireless headphones (100) can be modified or suspended by the headphones checking the type of audio source (330), receiving at least one parameter wirelessly, and automatically selecting an operating mode (340) depending on the parameter. The headphones can choose between a first operating mode (350) and a second operating mode (360), the first operating mode (350) corresponding to a first volume characteristic curve (210) with a first maximum volume (250) that is prescribed for open systems.The second operating mode (360) corresponds to a second volume characteristic (220) with a higher second maximum volume, which is only selected if the parameter indicates that the system is closed. Based on the volume characteristic (210, 220) corresponding to the selected operating mode, a user can adjust the playback volume of the headphones using a user interface (4202).

Description

[0001] Safety requirements for audio / video, information, and communication technology equipment used for the voluntary and intentional listening to entertainment, information, or communication content are regulated by the international standard IEC 62368-1. This standard also covers audio playback via headphones, specifying a maximum volume of 100 dB. SPL required to protect users' hearing from damage.

[0002] Audio playback devices often contain circuitry for volume limiting. An example is known from EP2224749 B1. This describes a method for controlling the maximum signal level output to headphones connected by cable to a wireless device. For this purpose, the impedance of the headphones and a carrier-specific maximum signal level for headphones with this impedance are determined. An audio amplifier in the wireless device connected to the headphones is adjusted to limit the maximum signal level output to the headphones to the carrier-specific maximum value.

[0003] More recently, headphones are mostly connected wirelessly to an audio playback device. Volume is often limited independently in both the playback device and the headphones. This can lead to a situation where the maximum permissible volume is not reached.

[0004] A problem that is increasingly common among headphone users is that the playback volume is perceived as insufficient in certain situations. Besides the aforementioned dual limitation, this can be due to a user not wearing a hearing aid despite already having mild hearing loss. It could also be that a user doesn't use their hearing aid because it is incompatible with the headphones and they simply prefer headphones. Typically, the problem can arise in noisy environments or when an audio playback device, such as a television, outputs a signal that is not loud enough. However, for headphones, further increasing the volume may be impermissible due to the validity of the standard and the general potential for hearing damage. Summary of the invention

[0005] It is therefore an object of the present invention to enable at least a maximum permissible volume level for headphones. Furthermore, it may be desirable in certain cases where the standard does not apply or where (further) hearing damage is not to be expected, to modify or suspend a volume limit.

[0006] The problem is solved by a headphone according to claim 1. Claim 12 relates to a method according to the invention. According to the invention, the maximum playback volume in headphones is automatically limited, depending on the type of audio signal source (or audio source), either to a first sound pressure level or to a higher second sound pressure level.

[0007] Further advantageous embodiments are described in the dependent claims. Brief description of the drawings

[0008] Further details and advantageous embodiments are shown in the drawings. These show Fig. 1 different typical use cases for headphones; Fig. 2 a) a characteristic curve diagram; Fig. 2 b) a schematic representation of the switching between characteristic curves; Fig. 3. A flowchart of a process; and Fig. 4. A block diagram of a headphone. Detailed description of the invention

[0009] Fig. Figure 1 shows two typical use cases for headphones or headsets. In the first case, shown on the left, a user wears wireless headphones 100a to listen to music, make phone calls, etc., on the go and regardless of location (e.g., with a personal music player, PMP). The headphones use a standard wireless connection 110, e.g., Bluetooth, to a playback device 120 in an open system. This refers to a system in which separately sold products can be universally combined and exchange standardized data. To protect hearing and avoid disturbing others in the vicinity, a prescribed volume limit of a maximum of 100 dB is observed. In the second case, shown on the right, a user wears the headphones 100b at home to listen to a television program 140 (TV listener mode).A wireless connection 130 is used, which forms a closed system with the headphones 100b and the television 140. A closed system exists between defined devices, in this case in a domestic (non-public) environment: the headphones according to the invention can form a closed system with a specific, individual device or with any device of a specific device class. Different regulations apply to a closed system than to an open system, at least with regard to the maximum reproducible volume. The headphones 100b according to the invention, which can be the same headphones 100a, 100 as in the first case, recognize the individual device or device class of the audio source, i.e., the television 140, based on the data transmitted via the wireless connection 130, and switch from an "open" to a "closed" operating mode. This closed mode can offer different technical features.The device used as the audio source can optionally be individually defined as a device authorized for a closed connection, so that a closed connection can only exist with, for example, one's "own" television.

[0010] In one embodiment, different characteristic curves apply to the two operating modes. Fig. Figure 2 a) shows a characteristic curve diagram with two different characteristic curves between which the headphones can automatically switch. The abscissa indicates the volume set by the user (in percent), and the ordinate the sound pressure level SPL (in dB). When the headphones are in an open system, a first characteristic curve 210 applies, the values ​​of which are always below a first maximum value 250 (here: 100 dB). When the headphones are in a closed system, a second characteristic curve 220 applies, which also has values ​​above the first maximum value 250. This can apply from 60%, as in this example, or in other examples only from a higher volume set by the user (e.g., 60-95%, especially 80-90%). In at least part of the control range, the values ​​of the second characteristic curve 220 are higher than those of the first characteristic curve 210, with the difference being...The distance 240 can be larger or smaller depending on the volume setting. The second characteristic curve 220 is limited to a higher value, e.g., 120 dB or 110 dB, to protect the user's hearing and prevent overloading the headphones. Alternatively, and technically identical, the second characteristic curve 220 can be viewed as an extended first characteristic curve 210, which is then scaled accordingly by compressing the abscissa axis.

[0011] The headphones are suitable for both open and closed systems, automatically detecting the system type and switching accordingly. Therefore, the user can connect the headphones 100 to either the smartphone 120 or the television 140 at any given time. When the headphones are connected to the smartphone 120, the smartphone sends the standard data to the headphones 100 via the wireless connection 130; this data does not contain any explicit information about the system type (open / closed), so the headphones 100 assume an open system and use the standard first characteristic curve 210. However, when the headphones are connected to the television 140, the television informs the headphones 100 via the wireless connection 130 that it is in a closed system. The headphones 100 then automatically switches from the first characteristic curve 210 to the second characteristic curve 220.To avoid an unpleasant volume jump for the user during this switch, the currently set volume of 230 can be maintained, i.e., the average sound pressure level remains constant.

[0012] If the user later uses the headphones 100 again in an open system, for example, connecting them to the smartphone 120, the headphones 100 automatically switch back to the first characteristic curve 210. When switching back from the second characteristic curve 220 to the first characteristic curve 210, the volume also remains constant at 230 if it is below the maximum value of 250 before switching back. However, if it is above the maximum value of 250 when switching back, it is reduced.

[0013] In one example, this reduction to the maximum value of 250 occurs, as in Fig. Figure 2 b) illustrates this. In this open system, volume levels are possible within a first range (here: between 1 and 5), while in a closed system, values ​​are possible within a larger second range (here: between 1 and 8). The higher values ​​6-8 correspond to higher volumes, i.e., higher sound pressure levels. When switching to a closed system (left), the volume levels remain constant, and the user notices no difference, except that the volume can be increased further. When switching back to an open system (right), the volume levels also remain constant, provided they do not exceed the maximum value of 5. However, if the value previously set by the user is above the maximum value (here 6-8), the volume is reduced to the maximum value of 5.

[0014] In another example, the reduction is achieved by adjusting the volume to a value corresponding to the same user-set volume (in percent) or sound pressure level, i.e., following a vertical line 240 in diagram 200, or to a volume last set or preferred in an open system and stored in the headphones. Similarly, a preferred volume or a volume last set in a closed system can be stored in the headphones. In this case, however, an automatic increase in volume when switching from an open to a closed system should be avoided or at least delayed for a minimum period (e.g., 3-10 seconds) to prevent startling the user.

[0015] Fig. Figure 3 shows a flowchart of a method 300 according to the invention for automatic volume limiting in wireless headphones. When switched on, the headphones can optionally be in a standby state 310, in which they can be connected to an audio source until audio playback is requested 320. The headphones check the type of audio source 330 and decide 340 whether it is a closed or an open system. In the case of an open system, volume levels up to the "normal" volume limit 350 are permitted, e.g., according to a first characteristic curve 210. In the case of a closed system, higher volume levels are also permitted 360, as described above, e.g., according to a second characteristic curve 220. Then audio playback 370 can begin. The selected setting remains in effect until the headphones connect to a different audio source 380.In a particular variant, in one embodiment of the invention, the signaling sent by the audio source can alternatively change, for example, if the usage pattern of the audio source changes over time, such as when a device that is actually mobile is operated in a stationary position or vice versa.

[0016] To determine the type of audio source (330) and whether it is a closed or open system (340), the headphones evaluate a signal. The audio source can insert this signal at a suitable location, such as a Bluetooth (BT) attribute, in data packets used to establish the connection between the devices, or in the header of normal audio data packets according to BT or BT Low Energy (BLE). Depending on the signal, a processor in the headphones can change software and / or hardware parameters to activate the higher or lower volume limit.

[0017] Fig. Figure 4 shows a block diagram of a headphone 100. The headphone 100 contains a radio interface 410, an audio processing unit 420, which can also be used for, e.g., active noise cancellation (ANC), an amplifier 4204, and a transducer 430. Certain components, e.g., the transducer 430 and amplifier 4204, can be duplicated, one for each side of the headphone, as is common practice. The audio processing unit 420 contains a volume control 4201, which the user can operate via a user interface 4202, e.g., a control on the headphone and / or a virtual control on the audio source, to select a volume level between 0% and 100% along a characteristic curve, as shown in Figure 4. Fig.Figure 2 illustrates this. When establishing or modifying the wireless connection, the audio processing unit 420 can receive one or more parameters from the radio interface 410 that define the type of audio source and thus the type of audio playback, in particular whether it is an open or a closed system. The absence of such a parameter is interpreted as an open system. This parameter, or a corresponding characteristic value (e.g., a bit), is stored in a memory 4203 and determines the maximum adjustable volume that the user can set via the user interface 4202, as described above. The user interface 4202 itself and the earphone settings can remain unchanged from the user's perspective; that is, a switchover need not be immediately noticeable to the user.

[0018] In one embodiment, conventional headphones do not use the signaling or parameter, but rather ignore it. The audio source device can be informed—but doesn't have to be—whether the headphones are using the signaling. In another variant, a signaling is used that is implicit or actually serves a different purpose. For example, the device's MAC address can be set to a specific range of values, e.g., addresses beginning with 80:AA. hex start.

[0019] In one embodiment, the maximum value of 250 dB can also be below 100 dB, e.g., at 70 dB, to allow only lower maximum volume levels (for example, for children or for general hearing protection). The playback device can then inform the headphones whether the user has set a volume limit or disabled it. The headphones can then only reproduce a lower maximum volume when connected to certain devices (e.g., those used by children), but the "normal" maximum volume in other cases.

[0020] As an alternative to Bluetooth, the headphones according to the invention can also use other types of connection, e.g., wired or wireless via Wi-Fi. In these cases, the signaling can be adapted accordingly, which is easy for a person skilled in the art based on the present description. Audio sources generally refer to devices that function as audio signal sources, such as smartphones, computers, televisions, radios, etc.

[0021] As an alternative to maximum volume, other parameters can in principle also be transmitted to the headphones in order to control or unlock functions in the headphones depending on the current operating mode, and in particular to set or change limits.

[0022] The invention can be implemented using a configurable computer or processor. Configuration is achieved using a computer-readable data carrier containing instructions suitable for programming the computer or processor to perform the steps of the method described above. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] EP 2224749 B1

[0002]

Claims

[1] Wireless headphones (100) with - a radio receiver (410); - an audio data processing unit (420); and - at least one transducer (430) for playing back audio data received by the radio receiver (410) and processed by the audio data processing unit (420); - wherein the audio data processing unit (420) includes a volume control (4201) which follows a characteristic curve (210, 220) depending on a user interface (4202), characterized by , that - the volume control (4201) can switch between at least two characteristic curves (210, 220) that allow different maximum volume levels, and - the volume control (4201) receives at least one wirelessly received parameter from the radio receiver (410) and selects one of at least two characteristic curves (210, 220) depending on the value of the parameter. [2] Headphones according to claim 1, wherein the parameter contains information about a transmitting device from which the radio receiver (410) has wirelessly received the parameter. [3] Headphones according to claim 1 or 2, wherein the second characteristic curve (220) allows a greater maximum volume than the first characteristic curve (210) and is selected in such cases where the parameter meets a certain condition, and wherein the first characteristic curve (210) is selected in all other cases. [4] Headphones according to claim 3, wherein the first characteristic curve (210) enables a maximum user-adjustable volume of 100 dB. [5] Headphones according to one of claims 1-4, wherein the parameter is transmitted as a Bluetooth attribute. [6] Headphones according to one of claims 1-4, wherein the parameter is transmitted by a MAC address of the transmitting device, wherein the second characteristic curve (220) is selected when the MAC address of the transmitting device is within a certain range of values, and otherwise the first characteristic curve (210) is selected. [7] Headphones according to one of claims 1-6, wherein the parameter is transmitted at the beginning of the wireless connection and is stored as a characteristic value in a memory (4203) of the headphones. [8] Headphones according to one of claims 1-7, wherein the value of the wirelessly received parameter can change during operation, and wherein when the volume control (4201) changes from the first characteristic curve (210) to the second characteristic curve (220) upon a change of the parameter, the sound pressure level remains substantially constant (230). [9] Headphones according to claim 8, wherein when the volume control (4201) changes from the second characteristic curve (220) to the first characteristic curve (210) upon a change of the wirelessly received parameter, the sound pressure level is either reduced to the maximum value of the first characteristic curve or remains substantially constant. [10] Headphones according to claim 8 or 9, wherein the value of the wirelessly received parameter changes by wirelessly connecting the headphones to another transmitter. [11] Headphones according to claim 8 or 9, wherein the value of the wirelessly received parameter changes by switching the transmitting device to a different operating mode. [12] Method (300) for automatic volume limiting in a wireless headphone (100), the method comprising the following steps: - Connecting (310) the headphones to an audio source and requesting audio playback (320); - Checking (330) the type of audio source, wherein at least one parameter is received wirelessly from the audio source; - automatic selection (340) of an operating mode of the headphones depending on the wirelessly received parameter, wherein a choice can be made between a first operating mode (350) and a second operating mode (360), wherein the first operating mode (350) corresponds to a first volume characteristic (210) with a first maximum volume (250) and wherein the second operating mode (360) corresponds to a second volume characteristic (220) with a second maximum volume which is higher than the first maximum volume; and - Playback (370) of wirelessly received audio data through the headphones, whereby a user can adjust a volume based on the selected volume characteristic using a user interface (4202). [13] Method according to claim 12, wherein the second volume characteristic curve (220) is selected in cases where the parameter meets a certain condition, and wherein the first volume characteristic curve (210) is selected in all other cases. [14] Method according to claim 12 or 13, wherein the parameter is transmitted as a Bluetooth attribute or by a MAC address. [15] Method according to claim 12 or 13, wherein the parameter is transmitted as a Bluetooth attribute and leads to the selection of the first or second operating mode, and wherein at a later time a modified parameter is transmitted from the same audio source as a Bluetooth attribute, which leads to the selection of the other operating mode.

Images