MXPA00012847A - Radio broadcasting receiver has control unit that switches. - Google Patents

Abstract

TO FIRST OR SECOND OPERATION MODE BASED ON MONOSTEREO RECOGNIZER THAT DETERMINES IF OUTPUT DEVICE IS MONOAUDIO OUTPUT DEVICE OR STEREO AUDIO DEVICE A receiver (132), an audio circuit (119) and a stereo demodulator demodulates the stereo signals. A headphones jack (134) is used for coupling an audio output device. A monostereo recognizer (136) is coupled to the jack to determine if the output device is a monoaudio output device or a stereo audio device. A control unit (103) switches either to a first or a second operation mode based on the recognizer. An Independent claim is also included for a radio broadcasting receiving method.

Description

METHOD AND APPARATUS FOR THE MONOPHONIC AND STEREOFONIC OPERATION OF A RADIO RECEIVER FIELD OF THE INVENTION The present invention relates generally to radio receivers and transceivers. More particularly, the present invention relates to a method and apparatus for operating a radio receiver in a first mode or a second mode in response to detecting the coupling of a monophonic hearing instrument or is tereophonic thereto.

BACKGROUND OF THE INVENTION Radio receivers receive and demodulate radio frequency (RF) communication signals.

The demodulated RF signals are processed and presented audibly to a user of the receiver or are presented as digital signals to a receiver controller. One type of radio receiver is an amplitude modulated (AM) / frequency modulated radio (RM), typically known as an AM / FM radio.

Conventional AM / FM radios can receive and present to a user both AM onophonic signals and FM stereo signals. Many users listen to their radio receiver via a hearing aid. The hearing aid has headphones that cover the user's ears and provide the output of pl899 / 00MX Audio from the radio receiver efficiently and directly to the ears. A stereophonic hearing aid can be used to provide the user with a stereo audio output processed from FM stereophonic signals. In a stereophonic hearing aid the left earphone will provide a Left (L) signal to the left ear and a right earphone will provide a Right (R) signal to the right ear in a manner well known in the art. Typically, the hearing aid is coupled to the radio receiver using a conventional stereo plug-and-socket arrangement. Then the stereo plug can also receive a monophonic connector but will then typically provide only an individual channel of information. Additionally, many AM / FM radio receivers are portable and operate on battery power. Additionally, AM / FM receivers are being combined with other devices, such as wireless radio transceivers to additionally provide functionality to wireless devices and use the synergy of - the devices. However, these combined devices have a growing need for energy conservation to prevent rapid depletion of battery power. Therefore, there is a need for pl899 / 00MX a method and apparatus for the monophonic and stereophonic operation of a radio receiver that can optimize audio performance and current consumption by allowing an improved signal-to-noise ratio and improved energy conservation.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a block diagram of a radiotelephone according to the preferred embodiment of the present invention. Figure 2 is a diagram of stereophonic signals modulated in frequency (FM) according to the present invention. Figure 3 is a schematic diagram of a stereophonic hearing aid for coupling to the radiotelephone of Figure 1 according to the preferred embodiment of the present invention. Figure 4 is a schematic diagram of a monophonic hearing aid for coupling to the radiotelephone of Figure 1 according to the preferred embodiment of the present invention. Figure 5 is a schematic diagram of the radiotelephone detection circuit of Figure 1 according to the preferred embodiment of the present invention. Figure 6 is a block diagram of the AM / FM stereophonic receiver of Figure 1 according to the preferred embodiment of the present pl899 / 00MX invention Figure 7 is a flow diagram of the performance optimization routine of the radiotelephone of Figure 1 according to the preferred embodiment of the present invention. Figure 8 is a block diagram of the digital audio circuitry according to a first alternative embodiment of the present invention. Figure 9 is a block diagram of the digital audio circuitry according to a second alternative embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION An improved radio receiver is described which can detect whether a terephonic hearing instrument or a monophonic hearing aid is connected to the hearing aid plug and optimize the audio performance and current consumption in response to the latter. The preferred embodiment of the present invention is a cellular radiotelephone combined with a stereophonic frequency-modulated (FM) receiver. Turning now to Figure 1, a block diagram of a terephonic radio receiver integrated in a wireless communication device such as a cellular radiotelephone incorporating the present invention is shown. On the pl899 / 00MX preferred embodiment, an ASIC 101 frame generator, such as the CMOS ASIC available from Motorola, Inc., and a microprocessor 103, such as a 68HC11 microprocessor also available from Motorola Inc., combine to generate the necessary communication protocol for operate in a cellular system. The microprocessor 103 uses the memory 104 comprising the RAM 105, the EEPROM 107 and the ROM 109 to execute the steps necessary to generate the protocol and to perform other functions for the wireless communication device, such as writing to a display screen 113 , acceptance of the information and keypad 115, coupling to another device for transmitting or receiving information via the input / output (I / O) interface 116, or control of a frequency synthesizer 125. The audio circuitry 119 comprises converters from analog to digital (A / D) and from digital to analog (D / A), amplifiers and other components to process signals from a microphone 117 and a speaker 121 and to and from the microprocessor 103. A transmitter 123 transmits through an antenna 129 using carrier frequencies produced by the frequency synthesizer 125. The information received by the antenna 129 of the communication device enters the rece 127 bit who demodulates the symbols using the frequencies pl899 / 00MX carriers from the frequency synthesizer 125. The communication device may optionally include a message receiver and a storage device 130 that includes a digital signal processing means. The message receiver and the storage device can be, for example, an answering machine, digital, a radiolocation receiver, an instant card, a multimedia card. In accordance with the present invention, a second antenna 130 receives an FM stereophonic signal and provides the signal to an FM stereo receiver 132 for demodulation. The FM stereophonic receiver 132 operates under the control of the microprocessor 103 and provides the demodulated signal to the audio circuitry 119 for provision to the loudspeaker 121. Alternatively, a hearing aid plug 134 is coupled to the audio circuitry 119 to provide audio signals to the hearing aid if a hearing aid connector is attached to the plug 134. The hearing aid plug 134 is coupled to the mono / stereo hearing aid detector 136 via the connection 137 and the microprocessor 103 via the connection 138 for the operation according to with the preferred embodiment of the present invention as described in detail below. Instead of a discrete antenna 130 as it is. represented in Figure 1, pl899 / 00MX it could implement a combined antenna 129, 130 or an antenna could be implemented in a hearing aid and an antenna coupling will be integrated into the socket 134 for coupling thereto. With reference to Figure 2, a conventional FM stereophonic signal is shown in the frequency domain. As is well known to those skilled in the art, the stereophonic information is decomposed into a Left (L) signal corresponding to the audio information that is proposed to be heard by the left ear and a Right signal.

(R) that corresponds to the audio information that is proposed so that it can be heard in the right ear.

After reception, the baseband demodulation of the FM stereophonic signal produces an L + R signal with a bandwidth of 15 kHz in the audio portion of the RF spectrum. The demodulated signal additionally comprises an L-R signal and its image, both having a bandwidth of 15 kHz and separated by 8 kHz from the signal L + R. A stereophonic demodulator combines the L-R signal with the L + R signal in the audio portion of the RF spectrum by adding them to obtain an L signal and subtracting them to obtain an R signal in a manner well known to those skilled in the art. With reference to Figure 3, a hands-free accessory 200 is shown for the cellular radiotelephone of Figure 1 incorporating a pl899 / 00MX hearing aid stereo that has a loudspeaker 202 of the left pavilion and a loudspeaker 204 of the right pavilion. The hands-free accessory also includes a hanging microphone 206. The accessory 200 allows the user to speak and listen to the cellular radiotelephone without holding it in their hands. This is particularly advantageous while you are driving or while you are working with your hands, such as typing or doing yard work. In accordance with the present invention, when the user is not in a cellular call, the hearing aid accessory 200 allows the user to listen to the integrated stereo FM radio. The hearing aid fitting 200 is coupled to the cellular radiotelephone by the hearing aid connector 208 that fits into the hearing aid plug 134 (Figure 1). The hearing aid connector 208 has a microphone contact 210, the right loudspeaker contact 212, the ground contact 214 and the left loudspeaker contact 216. The ground contact 214 is also connected to a shield 218 that protects the audio circuitry, such as the wire 220 that connects the microphone 206 to the connector 208, to decrease interference from the external sources. With reference to Figure 4, an alternative hands-free accessory 230 is shown for the cellular radiotelephone of Figure 1. The accessory P1899 / 00MX 230 differs from the accessory 200 (Figure 3) in that it incorporates a monophonic hearing aid having an individual speaker 232. This speaker can be two speakers, each in a pavilion, or a single loudspeaker that is coupled to the microphone 206 to allow the user talk and listen on the cellular radio or listen in mono to the integrated radio. The hearing aid fitting 230 can be coupled to the cellular radiotelephone by the hearing aid connector 234 which includes the microphone contact 210, the loudspeaker contact 236 and the ground contact 214. Referring now to Figure 5, a schematic diagram of the mono / stereophonic hearing aid detector 136 is shown. The ground connection of the hearing aid connector 214 (Figures 3, 4) is the sleeve of an audio connector, coaxial. Therefore, there will be two contacts in the socket that will touch the connector sleeve when inserted. The first connection is to ground and the second connection is a sense line 138 that rises through a resistor 400 of a large value at the radius. When the hearing aid is not present, the state of the sense line 138 will be high since it will be floating from a connectivity point of view. When the coaxial connector is inserted, the sense line 138 will be shortened to ground since the contact in the socket 74 will be located to touch the pl899 / 00MX cuff, which will also be in contact with the first contact that is the potential to ground. Therefore, the plug is used to shorten line 138 from ground to ground. This scheme is used to detect the complete presence of a hearing aid and to provide a signal on the sense line 138 to the microprocessor 103. The amplifier 402 of the left channel and the amplifier 404 of the right channel are part of the audio circuitry 119 (FIG. ) and serve to amplify the radio signals received from the stereophonic AM / FM receiver 132. The amplifier 404 of the right channel will provide an audio signal to the right speaker 204 (Figure 3) or to the monophonic speaker 232 (Figure 4) depending on which hearing aid 200, 230 is connected to the socket 124. The switches 401, 403 and 405 are part of the audio circuitry 119 and are under the control of the microprocessor 103 as described below to connect and disconnect the phone's audio, monaural audio and stereophonic audio. The switch 407 is selectable by the user and may allow the monophonic signal to be provided on the loudspeaker 121 via the amplifier 409 as described hereinafter. As will be understood by those skilled in the art, switches 401, 403, 405, 407 and the other switches described herein may be p! 899 / 00MX enable electronically, mechanically or with a computer program. The amplifier 402 of the left channel will be capacitively coupled via the capacitor 406 to the left-hand speaker 202 (Figure 3) to maintain the high CD voltage of the speaker 202. According to the preferred embodiment, when the amplifier 402 is turned on, the DC output voltage will be the VREF level of CD at the non-inverting input node of the amplifier 402. In addition, the switch 408 that connects the output node of the amplifier 402 to VREF will open. When the amplifier 402 is off, the output will be high impedance and the output node will be VREF. This change to VREF maintains a constant voltage in the output capacitor 406 and will prevent any triggering or clicking of audio when the amplifier 402 is enabled and disabled as described below because the capacitor 406 will not be charged or discharged during enabling and Disabling the amplifier 402. The mono / stereophonic hearing instrument detector 136 operates as follows. The speaker side of capacitor 406 will be brought to a buffered version of a fractional portion of VREF by amplifier 410. This voltage is preferably 3/4 of VREF, and is taken from a "clean" audio reference so that noise minimum will be coupled in pl899 / 00MX the speaker 202 when the hearing aid is connected. The voltage was deliberately chosen to be less than VREF to maintain correct polarization through the electrolytic capacitor 406 when a hearing aid is not present. This was done to allow a low cost electrolytic capacitor to be used for capacitor 406 instead of a more expensive ceramic bushing. Two lifting resistors 411, 412 are connected between the damped voltage and the speaker side of the output capacitor 406. The node 413 of the two resistors 411, 412 feeds a low pass filter formed by a resistor 414 and a capacitor 416 coupled to ground. The output of this low pass filter feeds the reversing terminal of a comparator 418. The two resistors 411, 412 prevent the negative from going to the audio signals on the loudspeaker 202 to cause potential damage to the input of the comparator 418 since the comparator 418 will be done preferentially using traditional IC manufacturing processes. The low pass filter 414, 416 also filters audio signals and prevents any signal from traveling falsely on the comparator 418 as well as limiting excursions of the negative voltage. When a stereo headset is connected 200 (Figure 3) at plug 134, a loudspeaker 202 of the left channel will be present and this will be detected on line 137 as follows. The typical speaker of P1899 / 00MX hearing aid is 32 ohms and when present, will bring the speaker side of capacitor 406 about the ground potential because the value of resistors 411, 412 are chosen to be much higher than the speaker's 32 ohm resistor, preferentially about 10 K ohms. This will create voltage at the reversing input of the comparator 408 less than the non-reversing input of the comparator 418. In this way, the output of the comparator 418 will be high when the stereophonic hearing aid 200 containing the speaker 202 of the left channel and the receiver is inserted. comparator 418 will provide a stereophonic hearing aid detection signal to microprocessor 103. When a monophonic hearing aid 230 is inserted (Figure 4), the left channel speaker will not be present, and the speaker side of the capacitor 406 will float to the damped voltage amplifier 410. This damped voltage will be present in the inversion node of the comparator 418 and, since it is greater than the noninverting input of the comparator 418, it will cause the output of the comparator 418 to be low. This will provide a monophonic hearing aid detection signal to the microprocessor. 103. Referring to Figure 6, a block diagram of the FM processing portion of the FM stereophonic receiver 132 is shown according to the preferred embodiment of the present invention.

P1899 / 00MX The signal received in the FM antenna 130 is provided to a front FM amplifier 502 and thence to an I / F mixer 504 and an FM detector 506 to generate a demodulated FM signal in the node 508 as shown in Figure 2. The FM signal is further demodulated by the stereophonic demodulator 510 which introduces the L + R portion to the adders 512, 514 and introduces the LR portion to a LR demodulator 516. An output of the demodulator LR 516 is provided as an inverted input to the adder 512 and as an input to the adder 514. The adders 512, 514 combine the two signals input to derive a signal L and a signal R for the provision to the audio circuitry 119. In accordance with the present invention, When a monophonic hearing aid is detected, the microprocessor 103 signals the FM receiver 132 to open the switch 518 and reduce the current consumption by reducing the energy of the LR demodulator 516. In this way, it is provided an L + R signal combined to the audio circuitry 119 for the 'provision to the monophonic hearing instrument. Referring now to Figure 7, a flow chart of the performance optimization routine of the microprocessor 103 is shown according to the preferred embodiment of the present invention. When the cellular radiotelephone with the integrated radio receiver is operating 600, the pl899 / 00MX Optimization routine first determines whether a stereophonic signal 602 is received at receiver 132. If a stereophonic signal is not received 602, then conventional processing of the audio signal is performed. However, if a stereophonic signal 602 is received and a hearing aid is not detected at the socket 134 by the detector 136, then the microprocessor 103 determines whether the user has selected 606 an option to provide the stereophonic signal to the loudspeaker 121 of the cellular radiotelephone. . If so, then the microprocessor 103 signals the FM receiver 132 to combine the signal L and the signal R and provide the signal L + R 608 to the amplifier 409 and then the loudspeaker 121. Additionally, according to the present invention, the amplifiers 402, 404 are decreased in energy to reduce the current consumption. If a hearing aid 604 is detected in the socket 134, the signal from the detector 136 is examined to determine 610 whether it is high or low by indicating whether the hearing aid is a stereophonic hearing aid 200 or a monophonic hearing aid 230. If the hearing aid detected is a stereo hearing aid 200 , the microprocessor 103 provides signals to the audio circuitry 119 to increase the power of the amplifier 612 of the right channel and to increase the power of the amplifier 614 of the left channel. The microprocessor 103 then provides a signal to the pl899 / 00MX receiver 132 to generate 616 an L signal and a R signal as described in conjunction with Figure 6. The microprocessor 103 then provides signals to the audio circuitry 119 to adjust the switch 401 to send the L signal to the left channel amplifier 617 and to adjust the switch 403 to send the signal R to the amplifier 618 of the right channel. If 610 is determined that the detected hearing aid is a monophonic hearing aid 230, the microprocessor 103 optimizes the performance of the cellular radiotelephone and the radio receiver to reduce the current consumption and use the audio performance. According to the preferred embodiment of the present invention, optimization is achieved by the microprocessor 103 providing signals to the audio circuitry 119 to increase the power of the right channel amplifier 620, but to decrease the power of the left channel amplifier 622. The microprocessor 103 then provides a signal to the receiver 132 to generate 624 a monophonic signal L + R and to provide it to the audio circuitry 119 as a signal R. Finally, the microprocessor 103 then provides signals to the audio circuitry 119 to adjust the switches 401, 403 and 405 to disconnect the left channel amplifier and to send the L + R signal to channel amplifier 626 pl899 / 00MX law . Thus, in accordance with the present invention, when the microprocessor 103 perceives that a stereo headphone is plugged into the socket 134, it will allow the left amplifier routes as right and will also send an order to the FM receiver 132 to transfer a stereo signal to the left and right channel audio amplifiers. If the microprocessor 103 senses that a monophonic hearing aid has been inserted, it will decrease the power of the left channel amplifiers to decrease the current consumption of the system and will order the FM receiver to go to a monophonic operation mode where it will transfer a monophonic audio signal (L + R) on the right channel to the speaker. The FM receiver will also narrow its RF reception bandwidth to capture only the L + R band and eliminate the L + R band, thereby improving the signal to noise ratio when a monophonic hearing aid 230 is detected is allowed that the user enjoys the complete audio signal L + R. If the combination of the signal, the user will only hear half of the signal in the monophonic hearing aid. The present invention is also capable of optimizing the operation of any digital audio information processing and the generation of audio signals thereof. According to the pl899 / 00MX preferred embodiment of the present invention, the digital audio information could be received via the input / output interface 116 or stored in the message storage device 130 or received as an RF signal via the antenna 129. The audio information is can receive or store as digital information in compressed or uncompressed formats. A digital audio data compression format is the third generation MPEG format referred to as MP3. Figures 8 and 9 represent two alternative embodiments of the present invention that process the digital audio information and generate the R and L signals in the audio circuitry 119. With reference to Figure 8, the digital audio data is received from the 116 I / O interface or antenna 129 and receiver 127, is not retrieved from storage device 130. Then he • provides a digital signal processor 802 (DSP) that can be implemented in the microprocessor 103, as a portion of the audio circuitry 119, or as a separate block. The processed digital audio data is transferred from the DSP 802 and converted to audio signals by the digital-to-analog (D / A) converter 803. The D / A converter 803 is a portion of the audio circuitry 119 generated an L signal and an R signal of the audio and digital data. The signal R pl899 / 00MX is coupled to a first input of an adder 804. The second input of adder 804 may have the signal L coupled thereto by the operation of switch 806. In this way, when a stereo hearing aid is detected by detector 136, the microprocessor 103 signals the switch 806 to open and an R signal amplified by the amplifier 808 and an L signal amplified by the amplifier 810 is provided to the hearing aid plug 134. When a monophonic hearing aid is detected by the detector 136, according to the present invention, the controller 103 optimizes the performance or reduces the current consumption by sending signals to the switch 806 to close and decrease the power of the amplifier 810. The summer 804 combines the signal L and the signal R and provides the signal L + R to the amplifier 808 for production to the plug 134 of the hearing aid. With reference to Figure 9, a second alternative mode combines the L and R signals in a computer program within a digital signal processor 900. The computer program 902 of signal processing receives the digital audio data and produces a first data stream comprising alternate frames of the data of the signal L and the data of the signal R and a second data stream comprising frames of the data of the L + R signal. According to the present invention, the computer program switch 904 P1899 / 00MX operates in response to a signal from the microprocessor 103 to choose which signal to provide the D / A converter 803, the microprocessor signal 103 generated in response to the type of hearing aid detected by the detector 136. If a stereo hearing aid is detected, the first current of data will be converted to audio by the D / A converter 803 and a signal R will be provided to the amplifier 808 and an L signal will be provided to the amplifier 810. If a monophonic hearing aid is detected, the second data stream will be converted by the D / D converter. At 803 and an L + R signal will be provided to the amplifier 808. According to the present invention, the switch 906 operates under the control of the microprocessor 103 to disconnect the amplifier 810, to allow the power decrease of the amplifier 810 when it is not needed thus inducing current consumption. In this way, it can be seen that the present invention reduces the current consumption by disabling the amplifiers of the left channel and controlling the AM / FM stereophonic receiver 132 to transfer only a monophonic audio signal (L + R) to the right channel ( R) when a monophonic hearing aid connector is inserted into the socket 134. When a stereo headset is connected, users will need to have the full stereo capability to maximize their enjoyment of pl899 / 00MX listen and both left and right amplifiers will be enabled and the stereophonic receiver 132 is controlled to transfer a stereophonic audio signal. In addition to reducing the current consumption by decreasing the power of the left channel amplifier, the reference voltage 410, damped and the comparator 418 (Figure 5) will be decreased in energy in normal operation. When a hearing aid connector is inserted into the socket 134, the routine - hearing aid detection will generate an interruption (step 604, Figure 7), the microprocessor 103 will enable the reference, damped voltage 410 and the comparator 418 and determine the state of the comparator 418 in step 610 to determine the type of connected hearing aid. Once the determination is made, the energy of the electronic perception circuitry will be decreased. Therefore, the circuitry will only be activated when a hearing aid is inserted or removed, thus saving additional current consumption in the telephone. Although the invention has been described and illustrated in the foregoing description and drawings, it is understood that this description is by way of example only and numerous changes and modifications can be made by those skilled in the art without departing from the true spirit and scope of the invention. the invention. For example, while the pl899 / 0OMX present invention has been presented in preferred and alternative embodiments of a cellular radiotelephone having a radio, stereophonic, integrated receiver, the invention can be implemented in a radio receiver having a hearing aid plug. Additionally, insofar as the preferred embodiment of the present invention has been analyzed in terms of two channels, one L channel and one R channel, the invention could be implemented in a device having more than two channels. Additionally, while the invention has been analyzed in terms of hearing aids and plug and connector coupling means, any audio transfer device (e.g., a loudspeaker or loudspeakers) is within the scope of the invention and the Plug can be any means of audio transfer coupling. Therefore, the invention should be limited only with the appended claims. pl899 / 00MX

Claims (5)

1. NOVELTY OF THE INVENTION Having described the present invention, it is considered as a novelty and, therefore, the content of the following CLAIMS is claimed as property: 1. A radio receiver for receiving stereophonic signals characterized by: circuitry for demodulating the signals stereophonic and generate from the same audio signals, the circuitry that performs demodulation and generation functions in either a first mode or a second mode; an audio transfer coupling means for coupling to an audio transfer device; a detection circuit coupled to the audio transfer coupling means to determine whether the audio transfer device coupled to the audio transfer coupling means is a monophonic audio device or a stereo audio device and to generate a detection signal in response to this; and a controller coupled to the detection circuit for receiving the detection signal thereof and coupled to the circuitry to provide a signal thereto for switching the circuitry from the first mode to the second mode in response to the pl899 / 00MX detection signal indicating that it is coupled to a monophonic audio device to the audio transfer coupling means.
2. 2. The radio receiver according to claim 1, further characterized by the circuitry that performs the demodulation of stereophonic signals and the generation of audio signals in the second mode uses less energy than performing the demodulation of stereophonic signals and the generation of audio signals in the first mode.
3. 3. The radio receiver according to claim 1, further characterized by the circuitry that performs the demodulation of the signals is tereophonic and the generation of audio signals in the second mode generates the audio signals that have a better signal-to-noise ratio of the audio signals generated by the circuitry that performs the demodulation of stereophonic signals and the generation of audio signals in the first mode. The radio receiver according to claim 1, further characterized by the detection circuit which additionally detects when an audio device is coupled to the audio transfer coupling means and provides a device detection signal to the controller, and is characterized additionally for p! 899 / 00MX the controller providing a signal to the circuitry for switching the circuitry from the first mode to the second mode in response to the device detection signal indicating that the audio device is not coupled to the audio transfer coupling means. The radio receiver according to claim 1, further characterized by a method for receiving stereophonic radio signals and generating audio signals thereof characterized by the steps of: receiving stereophonic signals; determine if a hearing aid is plugged into a socket; the detection circuit that determines whether the hearing aid connected to the jack is a stereo headset or a monophonic hearing aid in response to the determination that a hearing aid is plugged into the jack; the controller that demodulates the signals is tereophonic and generates the audio signals of the same in a first mode if the hearing aid connected to the plug is determined to be a hearing aid is terephonic; and the controller that demodulates the signals is tereophonic and that generates audio signals thereof in a second mode if it is determined that the hearing aid that is connected to the jack is a pl899 / 00MX Stereophonic hearing aid, where the second mode has less current consumption than the first mode. p! 899 / 00MX