EP2911415B1

EP2911415B1 - Power supply management for hearing aid

Info

Publication number: EP2911415B1
Application number: EP14156438.5A
Authority: EP
Inventors: Ole Gudiksen; Karsten Filsø JØRGENSEN
Original assignee: GN Resound AS
Current assignee: GN Hearing AS
Priority date: 2014-02-24
Filing date: 2014-02-24
Publication date: 2016-12-07
Anticipated expiration: 2034-02-24
Also published as: DK2911415T3; EP2911415A1

Description

FIELD OF TECHNOLOGY

A new hearing aid is provided that is configured to perform wireless communication with other devices while taking the state of a power supply of the hearing aid into account.
The wireless communication may be performed in a wireless network facilitating interconnection of a plurality of devices in the network, such as hearing aids, remote controllers, fitting instruments, mobile phones, headsets, door bells, alarm systems, broadcast systems, etc.

BACKGROUND

WO 2004/110099 discloses a hearing aid wireless network with a communication protocol that is simple thereby requiring a small amount of code and with low power consumption during operation. Further, the acquisition time is low, and the latency is low.
EP 2 200 207 A1 discloses a hearing instrument wireless network for wireless interconnection of hearing instruments with each other, and wireless interconnection of hearing instruments with other devices, such as remote controllers, fitting instruments, mobile phones, media players, headsets, door bells, alarm systems, broadcast systems, such as tele coil replacement, etc., etc., with an error correction scheme with low power consumption.
WO 2007/132023 A2 discloses a hearing system that is adapted to establish a communication network between devices of the hearing system. It is characterized by a main channel of said communication network, which uses at least a portion of the transmission capacity of said communication network, and which is shared between the devices. The sharing is managed jointly by the devices using a control channel. There is no centralized decision, but a distributed decision. Preferably, the main channel and the control channel are time-multiplexed.
EP 2 378 793 A1 discloses a hearing instrument with a power supply, wherein the hearing instrument includes an analogue-to-digital converter for conversion of an input audio signal to a digital input signal, a digital signal processor for processing the digital input signal into a processed signal, an audio amplifier for amplifying the processed signal, a wireless communication unit for wireless data communication between the hearing instrument and another device, and a stabilizing circuit having an energy storage unit and a rectifying element, wherein the energy storage unit is configured to supply power to one or more of the analogue-to-digital converter, the digital signal processor, and the audio amplifier, and the rectifying element is configured to prevent the energy storage unit from supplying power to the wireless communication unit.
EP 1 182 556 A2 teaches to schedule tasks like communication, decoding, and displaying, depending on battery power state, in a device having wireless communication.

SUMMARY

A new hearing aid is provided that is capable of performing wireless communication in accordance with a plurality of different wireless communication protocols.
A new hearing aid is provided, comprising a hearing aid circuit with
an input transducer configured to output an audio signal based on a signal applied to the input transducer and representing sound,
a hearing loss processor configured to compensate a hearing loss of a user of the hearing aid and output a hearing loss compensated audio signal, e.g., the hearing aid may aim to restore loudness, such that loudness of the applied signal as it would have been perceived by a normal listener substantially matches the loudness of the hearing loss compensated signal as perceived by the user,
an output transducer, such as a receiver, an implanted transducer, etc., configured to output an auditory output signal based on the hearing loss compensated audio signal that can be received by the human auditory system, whereby the user hears the sound, and
a wireless communication unit configured to communicate with another device.
A power supply is connected to supply power to the hearing aid circuit.
The hearing aid may further comprise a processor with an operating system configured to manage hearing aid hardware and software resources, e.g. including the hearing loss processor and possible other processors and associated signal processing algorithms, the wireless communication unit, memory resources, the power supply, etc., and to provide common services for tasks to be performed. The operating system may schedule tasks for efficient use of the hearing aid resources and may also include accounting software for cost allocation, including power consumption, of processor time, storage, wireless transmissions, and other resources.
For various tasks, such as wireless communication and memory allocation, the operating system acts as an intermediary between the tasks and the hearing aid circuit although the application code of the tasks is usually executed directly by appropriate hearing aid processing circuitry and will frequently make a system call to an operating system function or be interrupted by it.
The processor may be the hearing loss processor, or, the wireless communication unit may include the processor with the operating system, or the operating system may be distributed between various processors, such as the hearing loss processor and a processor of the wireless communication unit and possibly one or more further processors.
In particular, the operating system may be configured to control the wireless communication unit to perform communication with other devices in accordance with a plurality of communication protocols and priorities of the communication tasks.
The operating system may comprise a scheduler, or the operating system may be constituted by a scheduler. The scheduler may be configured to receive communication requests from communication tasks and may schedule each of the communication tasks based on task priorities and a state of the power supply, such as a de-charged state of a battery of the power supply and/or of a capacitor of the hearing aid circuit.
A new method is also provided of scheduling wireless communication of a hearing aid comprising a hearing aid circuit with
an input transducer configured to output an audio signal based on a signal applied to the input transducer and representing sound,
a hearing loss processor configured to compensate a hearing loss of a user of the hearing aid and output a corresponding hearing loss compensated audio signal,
an output transducer configured to output an auditory output signal based on the hearing loss compensated audio signal that can be received by the human auditory system resulting in the user hearing sound,
a wireless communication unit configured to communicate with another device,
a power supply connected to supply power to the hearing aid circuit, and an operating system configured to control the wireless communication unit to communicate with other devices in accordance with respective communication protocols and priorities.
The new method may comprise receiving communication requests from communication tasks, and scheduling the communication tasks based on task priorities and a state of the power supply.
A transducer is a device that converts a signal applied to the transducer in one form of energy to a corresponding output signal in another form of energy.
The input transducer may comprise a microphone that converts an acoustic signal applied to the microphone into a corresponding analogue audio signal in which the instantaneous voltage of the audio signal varies continuously with the sound pressure of the acoustic signal.
The input transducer may also comprise a telecoil that converts a varying magnetic field at the telecoil into a corresponding varying analogue audio signal in which the instantaneous voltage of the audio signal varies continuously with the varying magnetic field strength at the telecoil. Telecoils may be used to increase the signal to noise ratio of speech from a speaker addressing a number of people in a public place, e.g. in a church, an auditorium, a theatre, a cinema, etc., or through a public address systems, such as in a railway station, an airport, a shopping mall, etc. Speech from the speaker is converted to a magnetic field with an induction loop system (also called "hearing loop"), and the telecoil is used to magnetically pick up the magnetically transmitted speech signal.
The input transducer may further comprise at least two spaced apart microphones, and a beamformer configured for combining microphone output signals of the at least two spaced apart microphones into a directional microphone signal.
The input transducer may comprise one or more microphones and a telecoil and a switch, e.g. for selection of an omni-directional microphone signal, or a directional microphone signal, or a telecoil signal, either alone or in any combination, as the audio signal.
Typically, the analogue audio signal is made suitable for digital signal processing by conversion into a corresponding digital audio signal in an analogue-to-digital converter whereby the amplitude of the analogue audio signal is represented by a binary number. In this way, a discrete-time and discrete-amplitude digital audio signal in the form of a sequence of digital values represents the continuous-time and continuous-amplitude analogue audio signal.
Throughout the present disclosure, the "audio signal" may be used to identify any analogue or digital signal forming part of the signal path from the output of the input transducer to an input of the hearing loss processor.
Throughout the present disclosure, the "hearing loss compensated audio signal" may be used to identify any analogue or digital signal forming part of the signal path from the output of the hearing loss processor to an input of the output transducer possibly via a digital-to-analogue converter.
The wireless communication unit may comprise a transceiver.
The wireless communication unit may be a device or a circuit comprising both a wireless transmitter and a wireless receiver. The transmitter and receiver may share common circuitry and/or a single housing. Alternatively, the transmitter and receiver may share no circuitry, and the wireless communication unit may comprise separate devices with the transmitter and the receiver, respectively.
The wireless communication may be performed according to a frequency diversification or spread spectrum scheme, i.e. the frequency range utilized by the hearing aid is divided into a number of frequency channels, and wireless transmissions switch channels according to a predetermined scheme so that transmissions are distributed over the frequency range.
A frequency hopping algorithm may be provided that allows devices in the network to calculate what frequency channel the network will use at any given point in time without relying on the history of the network, e.g. based on the present frequency channel number, a pseudo-random number generator calculates the next frequency channel number. This facilitates synchronization of a new device with the hearing aid, e.g. the new device comprises the same pseudo-random number generator as the hearing aid.
Thus, upon receipt of the current frequency channel number during acquisition, the new device will calculate the same next frequency channel number as the hearing aid.
Every device in the network has its own identification number, e.g. a 32-bit number. Globally unique identities are not required since the probability of two users having hearing aids with identical identifications is negligible.
Preferably, a new device is automatically recognized by the network and interconnected with the network.
It is an advantage of a network operating according to a spread spectrum scheme that the communication has a low sensitivity to noise, since noise is typically present in specific frequency channels, and communication will only be performed in a specific frequency channel for a short time period after which communication is switched to another frequency channel.
Further, several networks may co-exist in close proximity, for example two or more hearing aid users may be present in the same room without network interference, since the probability of two networks simultaneously using a same, specific frequency channel will be very low. Likewise, the hearing aid network may coexist with other wireless networks utilizing the same frequency band, such as Bluetooth networks or other wireless local area networks.
The hearing aid may advantageously be incorporated into a binaural hearing aid system, wherein two hearing aids are interconnected, e.g., through a wireless network, for digital exchange of data, such as audio signals, signal processing parameters, control data, such as identification of signal processing programs, etc., etc., and optionally interconnected with other devices, such as a remote control, etc.
Typically, only a limited amount of power is available from the power supply of a hearing aid. For example, power is typically supplied from a conventional ZnO₂ battery in a hearing aid.
In the design of a hearing aid, the size and the power consumption are important considerations. The size of a hearing aid is dependent on the size of the battery used, and to ensure compact and inconspicuous hearing aids, small battery sizes, such as the types "312" and "13", are used. However, small batteries have a relatively large internal resistance. For example, a "312" battery typically have an internal resistance of 5 ohm which is two orders of magnitude higher than an internal resistance of an AA type battery. The high internal resistance leads to significant drop in output voltage at increased output current. This may be critical for the operation of parts of the hearing aid circuit.
The wireless communication unit of the hearing aid may be comprised in a radio chip, such as the Nordic Semiconductor radio chip "nRF24101", commonly operating at voltages above those available in a conventional ZnO₂ battery. Therefore it may be required to supply power to the radio chip via a voltage doubler (voltage amplifier). Furthermore, a radio chip draws significant amounts of current during transmission and reception. A conventional ZnO₂ battery is only capable of supplying the required amount of current drawn by the wireless communication unit during transmission and reception for a limited time period, typically 1 millisecond. In the event that the battery continues to supply the required amount of current for longer time periods, the supply voltage will decrease, and below a certain threshold, the hearing aid circuitry, in particular digital parts of the hearing aid circuitry, will not operate properly.
Further, the ZnO₂ battery will require time to recover after having supplied current, even for limited time periods, to the radio chip during communication. Typically, the radio chip duty cycle, i.e. the percentage of radio turn-on time with respect to the sum of the radio turn-on and radio turn-off time, must be kept below 10 %.
This problem may be alleviated by connection of a circuit with a resistor and a capacitor between the power supply of the hearing aid circuit and a supply voltage input of the wireless communication unit, e.g. between the output of the voltage doubler and a power supply input of the radio chip. The capacitor will deliver peak currents to the wireless communication unit so that peak currents drawn from the power supply is lowered, and the resistor will limit currents drawn from the power supply by the wireless communication unit during capacitor voltage drops.
The scheduler may be configured to calculate an earliest possible start time for performing a next communication task based on an estimated power consumption of the current or most recent communication task, in order to provide a recovery time period for the power supply, such as the above-mentioned battery and/or capacitor, between finalization of the current or most recent communication task and start of the next communication task.
The recovery time period to be applied after finalization of a communication task performed by the wireless communication unit may be calculated as a constant multiplied by an estimate of a duration, or an actual duration, of the communication task performed by the wireless communication unit.
The estimated duration may be constituted by the added time periods of pre-processing, transmission, reception, and post-processing of the communication task.
The actual duration may be constituted by the added time periods during which the wireless communication unit is actually powered during the execution of the communication task. Thus, possible powered down periods of the wireless communication unit during execution of the communication task do not add to the recovery time period, when the actual duration is used for calculation of the recovery time period.
The constant may range from 0.5 to 2, preferably from 0.6 to 1.8, more preferred from 0.7 to 1.5, most preferred from 0.8 to 1.4. For example, the constant may be equal to 1.125.
The recovery time period to be applied after finalization of a communication task performed by the wireless communication unit may be calculated from the charge or current drawn from the power supply during performance of the communication task.
The scheduler may take battery state, i.e. the state of de-charge of the battery, into account when calculating the recovery time period. For example, the above-mentioned constant may be increased as a function of a de-charged state of the battery.
The communication request may contain a priority of the communication task.
The communication request may contain a requested start time for performing the requested communication task.
The communication request may contain duration of performing the requested communication task.
The scheduler may determine that the requested start time is not available and may communicate to the requesting task that another start time has to be requested.
The scheduler may determine that an already scheduled task cannot be performed at the scheduled start time, e.g. due to a request with a higher priority, and may communicate to the already scheduled task that a new start time must be requested.
The scheduler may be configured to allow a communication task with a lower priority to perform communication before a communication task with a higher priority provided that the communication task with the lower priority will finalize its communication in time for the associated recovery time period of the lower priority task to elapse before start of the communication task with the higher priority.
The scheduler may also schedule other tasks than wireless communication tasks, and thus, the scheduler may be configured to receive task requests from other tasks than wireless communication tasks and may schedule each of the tasks according to task priorities and a state of the power supply.
The scheduler may also take power consumption of other tasks than wireless communication into account when scheduling. Examples of other tasks include power consuming algorithms, storage in flash memory, etc. The recovery time period for such other tasks may be calculated in the same way as explained above with relation to the recovery time period for wireless communication tasks. The constant may be different for different types of tasks, e.g. due to differences in power consumption.
The scheduler may be configured to power down one or more parts of the hearing aid circuit to avoid excessive power consumption due to simultaneous operation of power consuming circuits.
For example, the scheduler may be configured to turn off the wireless communication unit for a sleep time period, e.g. during writing to and/or reading from a flash memory, during performance of power consuming algorithms, etc.
Preferably, the scheduler is configured to schedule one next start time of each requested task , i.e. the scheduler is not configured to schedule a plurality of start times for a given task even though a plurality of start times may easily be determined, or already has been determined, for repeated performance of the given task, e.g. streaming audio. In this way, the number of scheduled task is kept low, whereby the scheduler is kept simple and dynamic since little re-scheduling will be required in response to a new request.
In the event that a communication task is finalized or terminated earlier than scheduled, the scheduler may be configured to re-calculate the recovery time period based on the actual duration and/or the actual power consumption of the communication task in question. After elapse of the re-calculated recovery time period and until the scheduled start time for the next scheduled task, there may be sufficient time to execute another task, and as mentioned above, the scheduler may be configured to allow another task, even with a lower priority than the next scheduled task, to be performed provided that the task will finalize in time for the associated recovery time period to elapse before start of the next scheduled task.
Signal processing in the new hearing aid may be performed by dedicated hardware or may be performed in one or more signal processors, or performed in a combination of dedicated hardware and one or more signal processors.
A protocol is a system of digital rules for data exchange within or between devices, e.g. in a network. A protocol defines the syntax, semantics, and synchronization of communication. A protocol can be implemented in hardware, software, or both.
A communication task includes the actions required to perform communication, e.g. transmission of a data package to the hearing aid. A communication request may be performed by another device or a processor in the hearing aid requiring co-operation with the communication unit of the hearing aid.
As used herein, the terms "processor", "signal processor", "controller", "system", etc., are intended to refer to CPU-related entities, either hardware, a combination of hardware and software, software, or software in execution.
For example, a "processor", "signal processor", "controller", "system", etc., may be, but is not limited to being, a process running on a processor, a processor, an object, an executable file, a thread of execution, and/or a program.
By way of illustration, the terms "processor", "signal processor", "controller", "system", etc., designate both an application running on a processor and a hardware processor. One or more "processors", "signal processors", "controllers", "systems" and the like, or any combination hereof, may reside within a process and/or thread of execution, and one or more "processors", "signal processors", "controllers", "systems", etc., or any combination hereof, may be localized on one hardware processor, possibly in combination with other hardware circuitry, and/or distributed between two or more hardware processors, possibly in combination with other hardware circuitry.
Also, a processor (or similar terms) may be any component or any combination of components that is capable of performing signal processing. For examples, the signal processor may be an ASIC processor, a FPGA processor, a general purpose processor, a microprocessor, a circuit component, or an integrated circuit.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following, the new method and hearing aid is explained in more detail with reference to the drawings, wherein

Fig. 1: Schematically illustrates a hearing aid according to the appended claims communication in a wireless network,
Fig. 2: Is a schematic diagram of one new hearing aid according to the appended claims,
Fig. 3: Illustrates slots and frames,
Fig. 4: Illustrates various task requests, and
Fig. 5: Shows a booking list and a list of prioritized tasks.

DETAILED DESCRIPTION OF EMBODIMENTS

In the following, various examples of the new method and hearing aid are illustrated. The new method and hearing aid according to the appended claims may, however, be embodied in different forms and should not be construed as limited to the examples set forth herein.
It should be noted that the accompanying drawings are schematic and simplified for clarity, and they merely show details which are essential to the understanding of the new method and hearing aid, while other details have been left out.
Like reference numerals refer to like elements throughout. Like elements will, thus, not be described in detail with respect to the description of each figure.
Fig. 1 schematically illustrates a binaural hearing aid 10L, 10R with a left ear hearing aid 10L and a right ear hearing aid 10R, each of which has a wireless communication unit for connection with a wireless network interconnecting the two hearing aids, and interconnecting the hearing aids 10L, 10R and a plurality of other devices in the wireless network. In the example illustrated in Fig. 1, a doorbell, a mobile phone, a cordless phone, a TV-set, and a fitting instrument are also connected to the wireless network.
An ID identifies every device. The ID is unique within the network.
The illustrated hearing aid network of Fig. 1 operates in the 2.4 GHz industrial scientific medical (ISM) band. It comprises 80 frequency channels of 1 MHz bandwidth. A frequency hopping time division multiplexing scheme is utilized. During acquisition, the frequency hopping scheme comprises a reduced number of frequency channels, e.g. less than 16 channels, preferably 8 channels, for faster acquisition. Members of the reduced set of frequency channels are denoted acquisition channels. Preferably, the acquisition channels are distributed uniformly throughout the frequency band utilised by the network.
Fig. 2 shows a schematic diagram of a new hearing aid 10.
The hearing aid 10 has a ZnO ₂ 12 battery that is connect for supplying power to the hearing aid circuit 14.
The hearing aid circuit 14 includes an input transducer 16 in the form of a microphone 16. The microphone 16 outputs an analogue audio signal 18 based on an acoustic sound signal arriving at the microphone 16 when the hearing aid 10 is operating.
An analogue-to-digital converter 20 converts the analogue audio signal 18 into a corresponding digital audio signal 22 for digital signal processing in the hearing aid circuit 14. In particular in a hearing loss processor 24A that is configured to compensate a hearing loss of a user of the hearing aid 10. Preferably, the hearing loss processor 24A comprises a dynamic range compressor well-known in the art for compensation of frequency dependent loss of dynamic range of the user often termed recruitment in the art. Accordingly, the hearing loss processor 24A outputs a digital hearing loss compensated audio signal 26. The hearing aid may be configured to restore loudness, such that loudness of the hearing loss compensated signal as perceived by the user wearing the hearing aid 10 substantially matches the loudness of the acoustic sound signal arriving at the microphone 16 as it would have been perceived by a listener with normal hearing.
A digital-to-analogue converter 28 converts the digital hearing loss compensated audio signal 26 into a corresponding analogue hearing loss compensated audio signal 30.
An output transducer in the form of a receiver 32 converts the analogue hearing loss compensated audio signal 30 into a corresponding acoustic signal for transmission towards an eardrum of the user, whereby the user hears the sound arriving at the microphone; however, compensated for the user's individual hearing loss.
The hearing loss processor 24A forms part of a processor A executing a part 36A of the operating system 36A, 36B of the hearing aid, and a memory 38A.
The hearing aid circuit 14 further includes a wireless communication unit B with a radio 34 that is configured to communicate wirelessly with other devices in a hearing aid network as illustrated in Fig. 1 for a binaural hearing aid system. The wireless communication unit B includes a processor executing a part 36B of the operating system 36A, 36B of the hearing aid, and a memory 38B and a processor 24B performing the various communication protocols and other tasks.
The operation of the hearing aid 10 is controlled by the operating system 36A, 36B. The operating system 36A, 36B is configured to manage hearing aid hardware and software resources, e.g. including the hearing loss processor 24A and possible other processors and associated signal processing algorithms, the wireless communication unit B, memory resources 38A, 38B, the power supply 12, etc., and the operating system 36A, 36B allocates the hearing aid resources to the tasks to be performed.
The operating system 36A, 36B schedule tasks for efficient use of the hearing aid resources and may also include accounting software for cost allocation, including power consumption, processor time, memory locations, wireless transmissions, and other resources.
For various tasks, such as wireless communication and memory allocation, the operating system acts as an intermediary between the tasks and the hearing aid circuit hardware although the application code of the tasks is usually executed directly by appropriate parts of the hearing aid circuit and will frequently make system calls to respective operating system functions or be interrupted by it.
In particular, the operating system 36B controls the radio 34 to perform wireless communication with other devices in accordance with various respective communication protocols and priorities of the various respective communication tasks.
The operating system 36B comprises a scheduler 40 that receives requests, including communication requests, from tasks to be performed. A communication request includes a priority of the communication task, a requested start time for performing the requested communication task, and expected duration of performing the requested communication task.
In response to the task requests, the scheduler 40 schedules each of the tasks based on task priorities and a de-charged state of a capacitor 42 supplying power to the radio 34 and being re-charged by the battery 12 through a resistor 44.
The circuit with the resistor 44 and the capacitor 42 may be omitted, i.e. the resistor 44 may be substituted with a short-circuit and the capacitor 42 may be substituted by an open-circuit, and in this case, in response to the task requests, the scheduler 40 schedules each of the tasks based on task priorities and a de-charged state of the battery 12.
The scheduler 40 calculates an earliest possible start time for performing a next communication task based on an estimated power consumption of the current or most recent communication task, in order to provide a recovery time period for the power supply, in the illustrated example the combination of the battery 12 and the capacitor 42, between finalization of the current or most recent communication task and start of the next communication task.
The recovery time period to be applied after finalization of a communication task performed by the radio 34 may be calculated as a constant multiplied by an estimate of the duration, or the actual duration, of the communication task performed by the radio 34.
The estimated duration may be constituted by the added time periods of pre-processing, transmission, reception, and post-processing of the communication task.
The actual duration may be constituted by the added time periods during which the radio 34 is actually powered during the execution of the communication task. Thus, possible powered down periods of the radio 34 during execution of the communication task do not add to the recovery time period, when the actual duration is used for calculation of the recovery time period.
In the illustrated hearing aid 10, the constant may be equal to 1.125.
In another example, the recovery time period to be applied after finalization of a communication task performed by the radio 34 may be calculated from the charge or current drawn from the power supply during performance of the communication task.
Further, the scheduler 40 may take power supply state, i.e. the state of de-charge of the battery 12 and/or the capacitor 42, into account when calculating the recovery time period. For example, the above-mentioned constant may be increased as a function of de-charge of the battery 12.
The scheduler 40 may determine that the requested start time is not available and may communicate to the requesting task that another start time has to be requested.
The scheduler 40 may determine that an already scheduled task cannot be performed at the scheduled start time, e.g. due to an incoming request with a higher priority, and may communicate to the already scheduled task that a new start time must be requested.
The scheduler 40 may be configured to allow a communication task with a lower priority to perform communication before a communication task with a higher priority provided that the communication task with the lower priority will finalize its communication in time for the associated recovery time period to elapse before start of the communication task with the higher priority. This may for example be useful in the event that a task is terminated or finalized in shorter time than the requested duration. This may leave room for another task to be executed before start of the next scheduled task.
The scheduler 40 may also take power consumption of other tasks than wireless communication into account when scheduling. Examples of other tasks include power consuming algorithms, storage in flash memory, etc. The recovery time period for such other tasks may be calculated in the same way as explained above with relation to the recovery time period for wireless communication tasks. The constant may be different for different types of tasks, e.g. due to differences in power consumption.
The scheduler 40 may be configured to power down one or more parts of the hearing aid circuit to avoid excessive power consumption due to simultaneous operation of power consuming circuits, such as the radio 34, flash memory, signal processors executing signal processing algorithms, etc.
For example, the scheduler 40 may be configured to turn off the radio 34 for a sleep time period, e.g. during writing to and/or reading from a flash memory, during performance of power consuming algorithms, etc.
Preferably, the scheduler 40 is configured to schedule the next start time of each task only, i.e. the scheduler 40 is not configured to schedule a sequence of start times for a given task even though a plurality of start times may easily be determined, or already have been determined, for repeated performance of the given task, e.g. streaming audio. In this way, the number of scheduled task is kept low, whereby the scheduler 40 is kept simple and dynamic since little re-scheduling will be required in response to a new request.
In the event that a communication task is finalized or terminated earlier than scheduled, the scheduler 40 may be configured to re-calculate the recovery time period based on the actual duration and/or the actual power consumption of the communication task in question. After elapse of the re-calculated recovery time period and until the scheduled start time for the next scheduled task, there may be sufficient time to execute another task, and as mentioned above, the scheduler 40 may be configured to allow another task, even with a lower priority than the next scheduled task, to be performed provided that the lower priority task will finalize in time for the associated recovery time period of the lower priority task to elapse before start of the next scheduled task.
One exemplary protocol is illustrated in Fig. 3, wherein the time is divided into so-called slots that have a length of 1250 µs (twice the length of a minimum Bluetooth™ slot). The slots are numbered from 0 to 255.
256 slots, i.e. slot 0 to slot 255, constitute a frame. Frames are also numbered.
Among factors influencing selection of the length of a slot, is the required lower latency of the system and a desired low overhead with respects to headers and Phase-Locked-Loop (PLL) locking.
Preferably, the slot length is a multiple of 625 µS, facilitating (i.e. does not prevent) that the protocol according to the invention can be implemented on BLUETOOTH™ enabled devices.
Each slot (except slot 128) is used for transmission by one specific device so that data collisions inside the network are prevented. Any slave device may transmit data in slot 128 and hence collisions may occur in this slot. The master device transmits timing information in slot 0. The slot and frame counters of a slave device are synchronized with the respective counters of the master device of the network.
A device may use one or more slots for transmission of data. Slots may be allocated during manufacture of a given device, or, slots may be allocated dynamically during acquisition. Preferably, the allocation table is stored in the master device.
Operation of the scheduler 40 is illustrated in Figs. 4 and 5.
Fig. 4 illustrates communication requests made by two communication tasks, namely Task 1 and Task 2. Task 1 may be a communication task relating to audio streaming, e.g. from a TV-set to the hearing aid performed in accordance with a hearing aid network communication protocol, and Task 2 may be a communication task relating to communication between a smart phone and the hearing aid performed in accordance with a Bluetooth Low Energy protocol. Each communication request contains start time, duration, and priority of the communication task to be performed. The duration includes pre-processing, transmission, reception, and post-processing of the communication task. In Fig. 4, the hatched areas indicate pre-processing and post-processing.
In the illustrated example, communication task 1 has made two communication requests so that audio data can be re-transmitted in the event that a first transmission (request 1) does not succeed. The second request has been made with high priority so that the probability of performing the second communication task at the requested time is high. In the example of Fig. 4, Communication task 1 has priority 2, communication task 2 has priority 3, and communication task 3 has priority 1. The highest priority has the lowest priority number.
Having received the communication requests, the scheduler 40 calculates the end times for each communication request as the sum of the requested duration d and the recovery time period allowing for power supply recovery. In the illustrated example, the recovery time period is equal to 9/8 times the duration.
Thus, end time₁ = t₁ + d₁ + 9/8*d₁ and end time₂ = t₂ + d₂ + 9/8*d₂ and end time₃ = t₃ + d₃ + 9/8*d₃.
Some communication tasks may not be active. For example, the remote controller may not have been used for some time. Active and non-active tasks are flagged as indicated in the Request List shown in Fig. 5. The parameters of a non-active task may be the now obsolete parameters of the most recent communication request.
As shown in Fig. 5, the scheduler 40 now schedules the communication tasks in accordance with the Request List and forms the shown priority list by listing the active communication requests in order of priority. Then, the scheduler identifies tasks with requests having end times earlier than the start time of the communication task with the highest priority (communication request 3 in the illustrated example). In the illustrated example, both communication request 1 and communication request 2 have end times earlier than t₃, in such a way that one of the corresponding tasks could be performed before start of the task with communication request 3. In this case, the communication task with the highest priority, namely the task with communication request 1 is performed.
In the event that the task with communication request 1 is performed successfully, the scheduler 40 deletes communication request 3, i.e. the second booking of communication task 1, since the audio data has now been successfully communicated. The scheduler 40 also determines that communication task 2 cannot be performed at the requested time; since end time₁ is larger than t₂, and a message is send to the requesting task that a new communication request must be made.
In the event that communication task 1 ends shortly after t₁, e.g. in the event that no header is detected due to noise, then a new end time is calculated based on a updated calculation of a correspondingly shorter recovery time, and in the event that the start time t₂ of communication request 2 is later than the new end time of communication task 1, then communication task 2 is performed because end time₂ is before start time t₃ of the higher priority communication request 3. If end time₂ had been later than t₃ then communication task 2 would have been re-scheduled, i.e. the scheduler 40 would have sent a message to the requesting task that a new communication request must be made.
In the event that communication task 1 ends shortly after t₁; however later than the previous example so that the new end time is later that t₂ then again, communication task 2 is re-scheduled, and the communication task of communication request 3 is performed.

Claims

A hearing aid (10) comprising a hearing aid circuit (14) and a power supply (12, 42) connected to supply power
to the hearing aid circuit (14) with
an input transducer (16) configured to output an audio signal (18) based on a signal applied to the input transducer (16) and representing sound,
a hearing loss processor (24A) configured to compensate a hearing loss of a user of the hearing aid (10) and output a hearing loss compensated audio signal (26), an output transducer (32) configured to output an auditory output signal based on the hearing loss compensated audio signal (26) that can be received by the human auditory system resulting in the user hearing sound, and
a wireless communication unit (B) configured to communicate with another device, and
an operating system (36A, 36B) configured to control the wireless communication unit (B) to perform communication with other devices in accordance with a plurality of communication protocols and priorities,
characterized in that
the operating system (36A, 36B) comprises
a scheduler (40) configured to receive communication requests from communication tasks and schedule each of the communication tasks based on task priorities and a state of the power supply (12, 42).
A hearing aid (10) according to claim 1, wherein the hearing aid circuit (14) comprises a capacitor (42) for supplying current to the wireless communication unit.
A hearing aid (10) according to claim 2, wherein the hearing aid circuit (14) comprises a resistor (44) connected between the power supply (12, 42) and the capacitor (42).
A hearing aid (10) according to any of the previous claims, wherein the scheduler (40) is configured to calculate an earliest possible start time for performing a next communication task based on an estimated power consumption of a current or most recent communication task in order to provide a recovery time period for the power supply (12, 42).
A hearing aid (10) according to claim 4, wherein the recovery time period is a constant multiplied by duration of the current or most recent communication task.
A hearing aid (10) according to claim 4, wherein the recovery time period is a function of the current drawn from the power supply (12, 42) during performance of the current or most recent communication task.
A hearing aid (10) according to any of claims 4 - 6, wherein the power supply (12, 42) comprises a battery (12), and wherein the recovery time period is a function of a state of the battery (12).
A hearing aid (10) according to any of the previous claims, wherein at least one of the communication requests contains a priority of the communication task.
A hearing aid (10) according to any of the previous claims, wherein at least one of the communication requests contains a start time for performing the requested communication task.
A hearing aid (10) according to any of the previous claims, wherein at least one of the communication requests contains duration of performing the requested communication task.
A hearing aid (10) according to any of the previous claims, wherein the scheduler (40) is configured to allow a communication task with a lower priority to perform communication before a communication task with a higher priority provided that the communication task with the lower priority will finalize its communication in time for an appropriate recovery time period of the power supply (12, 42) to elapse before start of the communication task with the higher priority.
A hearing aid (10) according to any of the previous claims, wherein the scheduler (40) is configured to turn off the communication unit for a sleep time period.
A hearing aid (10) according to any of the previous claims, wherein the scheduler (40) is configured to determine that the requested start time is not available and to communicate to the requesting task that another start time has to be requested.
A hearing aid (10) according to any of the previous claims, wherein the scheduler (40) is configured to determine that an already scheduled task cannot be performed at the scheduled start time, and to communicate to the already scheduled task that a new start time must be requested.
A hearing aid (10) according to any of the previous claims, wherein the scheduler (40) is configured to take power consumption of other tasks than wireless communication into account when scheduling.
A hearing aid (10) according to anyone of the previous claims, wherein at least a part of the operating system (36A, 36B) is contained in the hearing loss processor (24A).
A method of scheduling wireless communication of a hearing aid (10), comprising a power supply (12, 42) connected to supply power to a hearing aid circuit (14) with
an input transducer (16) configured to output an audio signal (18) based on a signal applied to the input transducer (16) and representing sound,
a hearing loss processor (24A) configured to compensate a hearing loss of a user of the hearing aid (10) and output a corresponding hearing loss compensated audio signal (26),
an output transducer (32) configured to output an auditory output signal based on the hearing loss compensated audio signal (26) that can be received by the human auditory system resulting in the user hearing sound,
a wireless communication unit (B) configured to communicate with another device, and
an operating system (36A, 36B) configured to control the wireless communication unit (B) to communicate with other devices in accordance with a plurality of communication tasks with respective communication protocols and priorities, the method comprising
receiving communication requests from the communication tasks, and
characterized in
scheduling an order according to which the communication tasks with the communication requests are to be communicated by the wireless communication unit (B) based on task priorities and a state of the power supply (12, 42).