Patent Publication Number: US-9854356-B2

Title: Headset noise-based pulsed attenuation

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The present application is a continuation of application Ser. No. 13/409,508, filed Mar. 1, 2012, which is a continuation-in-part of application Ser. No. 13/336,207 filed Dec. 23, 2011 by Paul G. Yamkovoy, the disclosure of which is incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     This disclosure relates to detecting occurrences of fast-onset environmental noise sounds detected by a talk-through microphone of a headset to momentarily attenuate talk-through audio. 
     BACKGROUND 
     With the advent of ever more effective forms of noise reduction headsets to reduce the environmental noise sounds that reach the ears of its user, and possibly impede the user&#39;s ability to use one or more features of the headset (e.g., listening to music, engaging in two-way communications, etc.), a growing need has been identified to in some way allow speech sounds of another person in the vicinity of the user to still reach the ears of the user so as to allow the user to carry on a conversation with that other person without removing at least a portion of it from at least one of the user&#39;s ears. This has led to the introduction of a “talk-through” (TT) functionality being added to such a headset that employs one or more filtering techniques to separate speech sounds of such another person from other environmental sounds, and to pass those speech sounds through whatever passive noise reduction (PNR) or active noise reduction (ANR) functionality is provided by such a headset, and onward to an ear of its user. Unfortunately, difficulties persist in the provision of both ANR and TT functionality arising from false triggering of audio compressors arising from certain relatively loud environmental sounds having relatively fast onset times (e.g., gun-shot sounds, sounds of explosions, etc.), or electrical noise arising from such events as electrostatic discharges that create pulses that resemble such relatively loud environmental sounds by also having relatively fast onset times. 
     SUMMARY 
     A headset having a talk-through microphones incorporates an audio circuit that compresses a signal representing sounds detected by the talk-through microphones in response to the audio circuit detecting the onset of a peak (positive and/or negative) in the signal that exceeds a predetermined voltage level (positive and/or negative voltage level, perhaps a predetermined magnitude of voltage from a zero voltage level), and that does so with a rate of change in voltage level that exceeds a predetermined rate of change in voltage level, the degree of compression possibly being a compression to or near a zero amplitude (perhaps to or near a zero voltage level) and the duration of the compression possibly being controlled by a timing circuit set to a predetermined period of time that may be retriggerable while amidst the predetermined period of time. 
     In one aspect, a method of controlling sounds acoustically output by an acoustic driver disposed within a casing of an earpiece of a headset includes compressing a signal representing sounds detected by a microphone of the headset that is acoustically coupled to the environment external to the casing in response to detecting an onset of a peak in the signal that exceeds a predetermined voltage level and that has a rate of change in voltage level that exceeds a predetermined rate of change. 
     In another aspect, a headset includes a first earpiece that includes a first casing and a first acoustic driver disposed therein; a first microphone carried by structure of the communications headset and acoustically coupled to an environment external to the first casing; and an audio circuit coupled to the first acoustic driver and the first microphone, the audio circuit receiving a signal representing sounds detected by the first microphone and providing an output to the first acoustic driver. The audio circuit compresses the signal in response to detecting an onset of a peak in the signal that exceeds a predetermined voltage level and has a rate of change in voltage level that exceeds a predetermined rate of change. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
         FIGS. 1 a  and 1 b    are each a perspective diagram of a headset. 
         FIGS. 2 a  and 2 b    are block diagrams of portions of a possible electrical architecture of the headset of  FIG. 1   a.    
         FIG. 3  is a block diagram of portions of a variant of the electrical architecture of  FIGS. 2 a  and 2 b    incorporating ANR. 
         FIGS. 4 a  and 4 b    are block diagrams of portions of a possible electrical architecture of the headset of  FIG. 1   b.    
     
    
    
     DETAILED DESCRIPTION 
     What is disclosed and what is claimed herein is intended to be applicable to a wide variety of headsets, i.e., devices structured to be worn on or about a user&#39;s head in a manner in which at least one acoustic driver is positioned in the vicinity of an ear; and to a wide variety of communications headsets, i.e., devices additionally structured such that a microphone is positioned towards the user&#39;s mouth to enable two-way audio communications. It should be noted that although specific embodiments of headsets incorporating a pair of acoustic drivers (one for each of a user&#39;s ears) are presented with some degree of detail, such presentations of specific embodiments are intended to facilitate understanding through examples, and should not be taken as limiting either the scope of disclosure or the scope of claim coverage. 
     It is intended that what is disclosed and what is claimed herein is applicable to headsets that also provide active noise reduction (ANR), passive noise reduction (PNR), or a combination of both. It is intended that what is disclosed and what is claimed herein is applicable to headsets meant to be coupled to any of a variety of audio devices, including and not limited to, an intercom system (ICS), a radio, or a digital audio player; and via wired and/or wireless connections. It is intended that what is disclosed and what is claimed herein is applicable to headsets having physical configurations structured to be worn in the vicinity of either one or both ears of a user, including and not limited to, over-the-head headsets, behind-the-neck headsets, two-piece headsets incorporating at least one earpiece and a physically separate microphone worn on or about the neck, as well as hats or helmets incorporating earpieces and/or microphone(s). Still other embodiments of headsets to which what is disclosed and what is claimed herein is applicable will be apparent to those skilled in the art. 
       FIGS. 1 a  and 1 b    depict embodiments of headsets  1000   a  and  1000   b  meant to be coupled to an audio device, such as an ICS, radio, tape player, digital audio player, etc. The headset  1000   a  is a communications headset for use in two-way audio communications, and incorporates a head assembly  100 , an upper cable  200 , a control box  300 , and a lower cable  400 . The headset  1000   b  is a simpler headset primarily for listening to audio, and incorporates a simpler form of the headset  100  and the lower cable  400 . 
     The head assembly  100  of both headsets  1000   a  and  1000   b  incorporates a pair of earpieces  110  that each incorporate one of a pair of acoustic drivers  115 , a headband  112  that couples together the earpieces  110 , and a pair of talk-through microphones  185 . The head assembly of the headset  1000   a  further incorporates a pair of feedforward ANR microphones  195 , a microphone boom  122  extending from one of the earpieces  110 , and a microphone casing  120  supported by the microphone boom  122  and incorporating a noise-canceling communications microphone  125 . Further incorporated into the casing of at least one of the earpieces  110  and/or of another component of the head assembly  100  is an audio circuit  600  electrically coupled to the acoustic drivers  115  (and/or coupled to the communications microphone  125  in the headset  1000   a ). As depicted, the headsets  1000   a - b  have an “over-the-head” physical configuration. However, despite the depiction of this particular physical configuration, those skilled in the art will readily recognize that the head assembly  100  may take any of a variety of other physical configurations, including physical configurations having only one of the earpieces  110  (and correspondingly, only one of the acoustic drivers  115 ), physical configurations employing a napeband meant to extend between the earpieces  110  about the back of a user&#39;s neck, and/or physical configurations having no band at all. Depending on the size of each of the earpieces  110  relative to the typical size of the pinna of a human ear, each of the earpieces  110  may be either an “on-ear” (also commonly called “supra-aural”) or an “around-ear” (also commonly called “circum-aural”) form of earcup. 
     The control box  300  of the headset  1000   a  incorporates a casing  330  that incorporates a control circuit  700 . The control box  300  may also incorporate one or more manually-operable controls  335  enabling a user of the headset  1000   a  to manually control aspects of various functions performed by the headset  1000   a . The control box may further incorporate at least a compartment (not shown) for a battery  345  and/or the battery  345 , itself, coupled to the control circuit  700 . In contrast, on the headset  1000   b , the control circuit  700 , the controls  335  and/or the battery  345  (if present) are incorporated into one or both of the casings  110 . 
     The upper cable  200  of the headset  1000   a  is made up principally of a multiple-conductor electrical cable extending between and coupling one of the earpieces  110  of the head assembly  100  to the control box  300 . In so doing, at least a subset of the conductors of the upper cable  200  couple and convey electrical signals between the audio circuit  600  of the head assembly  100  and the control circuit  700  of the control box  300 . In various possible variants of the headset  1000   a , the upper cable  200  may be formed with a coiled shape as a convenience to users of the headset  1000   a . Also, the upper cable  200  may additionally incorporate one or more connectors (not shown) on the upper cable  200  where the upper cable  200  is coupled to one of the earpieces  110  and/or where the upper cable  200  is coupled to the casing  330  of the control box  300 , thereby making the upper cable  200  detachable from one or both of the head assembly  100  and the control box  300 . In contrast, given that both the audio circuit  600  and the audio circuit  700  are incorporated into portions of the head assembly  100  such that the headset  1000   b  does not incorporate the control box  300 , the headset  1000   b  also does not incorporate the upper cable  200 . 
     The lower cable  400  is made up principally of another multiple-conductor electrical cable that extends from the control box  300  on the headset  1000   a  or extends from one of the earpieces  100  on the headset  1000   b . On the headset  1000   a , the lower cable  400  may be detachable from the control box  300  (via one or more connectors  480 ) with different variants ending with one or more connectors  490  (two variants being depicted) to enable the headset  1000   a  to be detachably coupled to a wide variety of audio devices. On the headset  1000   b , a single variant of the lower cable  400  may be more permanently coupled to one of the earpieces  110 . At least a subset of the conductors of the lower cable  400  couple and convey electrical signals between the control circuit  700  and circuitry of whatever audio device to which the connector(s)  490  may be coupled. In various possible variants, the lower cable  400  may be formed with a coiled shape as a convenience to users of the headset  1000 . 
     As more specifically depicted in  FIG. 1 a   , the headset  1000   a  may be able to be coupled to more than one audio device, perhaps incorporating a wireless transceiver enabling it to be coupled via wireless signals  985  (e.g., infrared signals, radio frequency signals, etc.) to a wireless device  980  (e.g., a cell-phone, an audio playback/recording device, a two-way radio, etc.) to thereby enable a user of the headset  1000   a  to additionally interact with the wireless device  980  through the headset  1000 . Alternatively or additionally, the headset  1000   a  may incorporate an auxiliary interface (e.g., some form of connector to at least receive analog or digital signals representing audio) enabling the headset  1000   a  to be coupled through some form of optically or electrically conductive cabling  995  to a wired device  990  (e.g., an audio playback device, an entertainment radio, etc.) to enable a user to at least listen through the headset  1000   a  to audio provided by the wired device  990 . Where the control box  300  incorporates the manually-operable controls  335 , the manually-operable controls  335  may enable a user of the headset  1000   a  to coordinate the transfer of audio among the headset  1000 , the wireless device  980 , the wired device  990 , and whatever audio device to which the headset  1000   a  may be coupled via the lower cable  400 . In contrast, the headset  1000   b  is not specifically depicted as having such capabilities, but alternate variants having such capabilities are certainly possible. 
       FIG. 2 a    depicts a possible embodiment of an electrical architecture  2000   a  that may be employed by the headset  1000   a . To facilitate understanding, the headset  1000   a  is depicted as being coupled to an audio device  9000 , which in this example, is a communications device enabling two-way audio communications such as an ICS or radio of a vehicle such as an airplane, a military vehicle, etc. Only portions of the audio device  9000  needed to facilitate discussion are depicted. Like  FIG. 1 a   ,  FIG. 2 a    depicts the coupling of the head assembly  100  to the control box  300  via the upper cable  200 , and depicts the coupling of the control box  300  to the audio device  9000  via the lower cable  400 .  FIG. 2 a    further depicts individual conductors of each of the cables  200  and  400 . 
     It should again be noted that the audio circuit  600  may exist entirely within the casing of only one of the earpieces  110 ; or may be divided into multiple portions, with portions distributed within the casings of each of the earpieces  110  (in variants of the headset  1000  having a pair of the earpieces  110 ), within the casing  120  that carries the communications microphone  125 , and/or elsewhere within the structure of the headset  1000   a . Thus, although the audio circuit  600  is depicted with a single block for ease of discussion, this should not be taken as an indication that the all of the audio circuit  600  necessarily exists within a single location of the structure of the headset  1000   a.    
     As depicted, in the electrical architecture  2000   a , audio-left and audio-right signals, along with an accompanying common system-gnd serving as a signal return, extend between the audio device  9000  and corresponding ones of the acoustic drivers  115  through conductors within the head assembly  100 , conductors of the cables  200  and  400 , and portions of the circuits  600  and  700 . The provision of the separate audio-left and audio-right signals enables the provision of stereo audio to ears of a user of the headset  1000   a . As also depicted, mic-high and mic-low signals extend between the audio device  9000  and the communications microphone  125  also through conductors within the head assembly  100 , conductors of the cables  200  and  400 , and portions of the circuits  600  and  700 . 
     As will be familiar to those skilled in the art, widespread industry practice and/or government regulations in specific industries often dictate that specific forms of audio device supporting two-way audio communications (e.g., the radio or ICS represented by the audio device  9000 ) provide a microphone bias voltage across the conductors associated with coupling a headset microphone to such forms of audio device to accommodate some types of microphones requiring a bias voltage. As will be familiar to those skilled in the art, it is considered a best practice to maintain the conductors coupling a headset microphone to an ICS or radio (e.g., the depicted conductors mic-low and mic-high) as entirely separate from the conductors coupling a headset acoustic driver to an ICS or radio (e.g., the depicted conductors audio-left, audio-right and system-gnd). As part of such best practice, any coupling of any ground conductor among the conductors associated with that microphone and those associated with that acoustic driver occurs only within the ICS or radio (as depicted with a dotted line within the audio device  9000 ) in an effort to avoid the creation of a ground loop extending along the length of whatever cabling couples a headset to an ICS or radio. 
     Further, and with somewhat less consistency even within a given industry, various forms of audio device supporting two-way audio communications may or may not provide a headset with electric power via at least one other conductor coupling that audio device to that headset (e.g., a communications device power conductor, as depicted). Where such power is so provided, it is usually referenced to whatever ground conductor is associated with an acoustic driver of that headset (e.g., the system-gnd conductor), and not one of the conductors associated with a microphone of that headset. As previously depicted and discussed, the lower cable  400  may be detachable from the control box  300  to allow different versions of the lower cable  400  having different versions of the connector(s)  490  to accommodate different forms of a communications device (i.e., different variations of the audio device  9000 ). As will be familiar to those skilled in the art, the connector(s) with which the audio device  9000  may be provided may or may not support the provision of electric power to a headset, and this may be one of the differences accommodated with different versions of the lower cable  400 . 
     Thus, as depicted, the control circuit  700  is provided with power from one or both of audio device  9000  (via the communications device power conductor of the lower cable  400 ) and the battery  345 . In keeping with other best practices, a ground conductor of the battery  345  is typically also coupled to the system-gnd. In turn, at least one head assembly power conductor of the upper cable  200  then conveys power provided to the control circuit  700  from whatever source to the audio circuit  600 . The headset  1000   a  may use that electric power in performing various functions including, and not limited to, amplifying audio for acoustic output by the acoustic driver(s)  115 , pre-amplifying audio detected by the communications microphone  125 , providing one or more forms of ANR (hence the dotted line depiction of the possible coupling of ANR microphone(s)  195  to the audio circuit  600 ), powering a wireless transceiver to send and/or receive audio (e.g., a wireless transceiver used to form the communications link  985 ), performing any of a variety of forms of signal processing on audio acoustically output by the acoustic driver(s)  115  and/or detected by the communications microphone  125 , and/or providing a talk-through (TT) function to enable selective passage of speech sounds from the environment external to the casing(s)  110  through whatever passive noise reduction (PNR) and/or ANR that may be provided by the headset  1000   a  so as to reach the ears of a user (hence the dotted line depiction of the possible coupling of talk-through microphone(s)  185  to the audio circuit  600 ). 
     As those skilled in the art will readily recognize, government regulations often require a degree of “failsafe” design be employed in headsets supporting two-way audio communications such that basic functionality for carrying out two-way communications (i.e., using a headset with whatever ICS or radio it may be coupled to) not be lost as a result of a loss of power to the headset. Thus, the acoustic driver(s)  115  and the communications microphone  125  must still be operational for two-way communications even if no power is provided by the audio device  9000 , the battery  345 , or any other source. Thus, it is common practice to provide a mechanism by which signals employed in such basic operation of the acoustic driver(s)  115  and the communications microphone  125  will bypass any amplification or other circuitry (i.e., be conducted among the connector(s)  490 , the acoustic driver(s)  115  and communications microphone  125  without interruption) when such power loss occurs. 
     With the manually-operable controls  335  carried by the control box  300 , and coupled to the control circuit  700  that is also at least partly located within the control box  300 , provision is made in the headset  1000   a  for signals to control audio functions performed by the audio circuit  600  to be conveyed via the upper cable  200  from the control box  300  to the head assembly  100 . What the audio circuit  600  is signaled to do in performing one or more functions may be determined by a user through their operation of the manually-operable controls  335  and/or may be determined in a more automated manner in response to available electric power. In one possible approach, electric power is conveyed by at least one head assembly power conductor of the upper cable  400  to the audio circuit  600  with a selectively variable voltage level as a mechanism to control one or more aspects of the performance of one or more of these various functions. In this way control signals may be conveyed from the control circuit  700  to the audio circuit  600  without use of distinct control conductors added to the upper cable  400  and without use of a digital serial signaling system that could add undesirably complex encoder and decoder circuitry to the control circuit  700  and the audio circuit  600 . Avoiding the addition of distinct control signal conductors and digital serial signaling reduces avenues for the introduction of electromagnetic interference (EMI) by reducing the quantity of conductors that may tend to act as antennae for receiving EMI, by avoiding the occurrence numerous transitions in voltage level and/or direction in current flow that accompanies the use of digital serial signals. Further, employing power conductors in dual roles of conveying power and conveying control signals also reduces avenues for the introduction of EMI due to their inherent tendency to act as AC-coupled shorts to ground. 
       FIG. 2 b    depicts portions of a possible implementation of the audio circuit  600  within the electrical architecture  2000   a  of  FIG. 2 a    germane to implementing talk-through functionality in greater detail. Thus, portions more germane to other features of the architecture  2000   a  have been omitted for sake of clarity. Also for sake of clarity, components of the audio circuit  600  associated with only one of the earpieces  110 , and not a pair of the earpieces  110 , are depicted. Thus, although what is depicted could be part of a form of the headset  1000   a  that incorporates a pair of the earpieces  110  (and therefore, at least a pair of the acoustic drivers  115 , as well as duplicate sets of associated components within the audio circuit  600 ), only one of the acoustic drivers  115  and its associated components within the audio circuit  600  are depicted to avoid unnecessary visual clutter. 
     As depicted, the audio circuit  600  in this variant of the electrical architecture  2000   a  incorporates a talk-through circuit  685  coupled to the acoustic driver  115 , a pulsed attenuator  680  coupled to the talk-through microphone  185  and to the talk-through circuit  685 , a differential amplifier  625  to tap electrical signals representing audio detected by the communications microphone  125  at its inputs, and an envelope detector  626  coupled to both the output of the differential amplifier  625  and to the talk-through circuit  685 . In turn, the talk-through circuit  685  is depicted as incorporating a controllable attenuator  686  coupled to and receiving the output of the pulsed attenuator  680 , a voltage-controlled attenuator  687  coupled to the output of the controllable attenuator  686 , an audio amplifier  688  coupled by its input to the output of the voltage-controlled attenuator  687  and by its output to the acoustic driver  115 , and an envelope detector  689  also coupled to the output of the audio amplifier  688  and coupled to a control input of the controllable attenuator  686 . The pulsed attenuator  680  is depicted as incorporating a microphone amplifier  684  coupled by its input to the talk-through microphone  185 , a comparator  683  coupled by its inputs to the output of the microphone amplifier  684  through a high-pass filter (formed by a capacitor and a resistor) and to a reference voltage source, a retriggerable monostable multivibrator  682  coupled by its input to the output of the comparator  683  and coupled by its output to the gate of a MOSFET, and an analog switch  681  coupled by a control input to the MOSFET and through which the controllable attenuator  686  is selectively coupled to the talk-through microphone  185  under the control of the MOSFET. 
     Again, it should be noted that only a single acoustic driver  115  and its associated circuitry within the audio circuit  600  (e.g., the talk-through circuit  685  and the pulsed attenuator  680 ) are depicted for sake of visual clarity. Thus, in embodiments of the headset  1000   a  having a pair of the earpieces  110 , there would be a pair of the acoustic drivers  115 , each having an associated one of a pair of the talk-through circuits  685  coupled to it, and the single envelope detector  626  would be coupled to each of those talk-through circuits  685 . Further, each one of the pair of the talk-through circuits  685  may have an associated one of a pair of the talk-through microphones  185  coupled to it through an associated one of a pair of the pulsed attenuators  680 . Alternatively, a single pulsed attenuator  680  associated with a single talk-through microphone  185  may be coupled to both talk-through circuits  685  of a pair of talk-through circuits  685 . 
     It should be noted that unlike the communications microphone  125 , the talk-through microphone  185  is not a noise-canceling microphone, and this reflects differences in the functions performed by each. It is advantageous and preferred that the communications microphone  125  be a noise-canceling type of microphone such that it is a near-field microphone that detects the speech sounds emanating from the mouth of a user of the headset  1000   a  in the near-field, while tending to ignore far-field sounds. In contrast, it is advantageous and preferred that the talk-through microphone  185  not be such a noise-canceling type of microphone such that it is able to detect far-field sounds (e.g., speech sounds emanating from someone other than the user), as well as near-field sounds. 
     As those familiar with talk-through functionality will readily recognize, the talk-through circuit  685  operates to convey speech sounds emanating from persons other than a user of the headset  1000   a , as detected by at least one talk-through microphone  185  (carried by a portion of the headset  1000   a  in a manner that acoustically couples it to the external environment, and to which the talk-through circuit  685  is indirectly coupled through the pulsed attenuator  680 ), to the acoustic driver  115  to allow the user to hear those speech sounds despite whatever PNR and/or ANR is provided by the headset  1000   a , which would otherwise normally prevent those speech sounds from being heard by the user. To avoid conveying sounds other than speech sounds through such PNR and/or ANR, the talk-through circuit  685  conveys only sounds detected by the talk-through microphone  185  that are within a predetermined range of audio frequencies associated with human speech. Although variants of the talk-through circuit  685  are possible that incorporate a distinct bandpass filter (not shown) that would separate sounds within such a range to be conveyed from sounds outside such a range (such that they are not to be conveyed), variants of the talk-through circuit  685  are possible that employ a band-limited variant of the audio amplifier  688  such that the audio amplifier  688  performs this bandpass filtering function in addition to amplification. 
     Within the talk-through circuit  685 , the envelope detector  689  and the controllable attenuator  686  cooperate to form one possible implementation of an audio compressor that monitors the amplitude of the output of the audio amplifier  688 , and that acts to reduce the amplitude of the audio signal received by the audio amplifier  688  from the talk-through microphone  185  in response to detecting instances of the amplitude of the output of the audio amplifier  688  provided to the acoustic driver  115  exceeding a predetermined threshold. Thus, this compressor created through this cooperation is a closed-loop compressor. It should be noted that alternate implementations of the talk-through circuit  685  are possible in which this audio compressor is not present and with the input of the audio amplifier  688  being more directly coupled to the talk-through microphone  185  (i.e., perhaps with only the voltage-controlled attenuator  687  and/or the pulsed attenuator  680  between them), and it should be noted that alternate implementations of the talk-through circuit  685  are possible in which such compression is provided by a compressor implemented in an entirely different manner (e.g., an open-loop compressor). However, it is seen as desirable to provide such audio compression functionality (in whatever way in which it may be implemented) in the talk-through circuit  685  as a safety feature to protect the hearing of a user of the headset  1000   a  by preventing excessively loud environmental sounds from being conveyed by the talk-through circuit  685  to an ear of the user. 
     The controllable attenuator  686  is formed from a combination of a capacitor, a resistor and a MOSFET coupled in a manner providing both AC coupling to the talk-through microphone  185  (through the analog switch  681  of the pulsed attenuator  680 ) and a variable voltage divider that will be readily familiar to those skilled in the art of audio compression. The gate input of the MOSFET of the controllable attenuator  686  is coupled to the output of the envelope detector  689  to enable the envelope detector  689  to operate that MOSFET to control the attenuation to which that MOSFET subjects the signal from the talk-through microphone  185 . 
     The envelope detector  689  is formed from a combination of a diode, resistors and a capacitor coupled in a manner that will also be readily familiar to those skilled in the art of audio compression. The anode of the diode is coupled to the output of the audio amplifier  688 , and its cathode is coupled to a first one of the resistors. In turn, the first one of the resistors is further coupled to the capacitor and the second one of the resistors (both of which are further coupled to ground), as well as to the gate input of the MOSFET of the controllable attenuator  686 . The diode enables current to flow from the output of the audio amplifier  688  in a manner that charges the capacitor through the first resistor (with the first resistor controlling the rate of charging), but does not allow that charge to be subsequently drained by the output of the audio amplifier  688 . Instead, it is the second resistor that provides a controlled rate of drain of that charge—the gate input of the MOSFET of the controllable attenuator  686  having too high an impedance to ground to provide another path of current flow by which the capacitor may be drained. Thus, the envelope detector, effectively acts as an integrator of peaks in the audio signal output by the audio amplifier  688 , with the capacitor storing a charge built up by the higher amplitudes of the output of that signal, and discharging at a controlled rate through the second resistor, with the resulting voltage level to which the capacitor has been charged being presented to the gate input of the MOSFET. 
     It should be noted that the depiction of the envelope detector  689  in  FIG. 3  may be more symbolic of its theory of operation than schematic, as various component substitutions may be made as those skilled in the art will readily recognize. For example, the depicted passive diode may be replaced with an active circuit having a behavior that more closely befits an ideal diode in which the forward bias voltage drop is (or is quite close to) zero. It should also be noted that since the diode and the first resistor are coupled in series to convey the output of the audio amplifier  688  therethrough, the order in which they are depicted as being coupled may be reversed. It should further be noted that, as depicted, the envelope detector  689  is a variant of half-wave envelope detector that detects only positive peaks (while ignoring negative peaks), and that as an alternative, full-wave variants are possible that detect both positive and negative peaks. In other words, to put it more broadly, the envelope detector  689  may be implemented in any of a variety of ways other than what is depicted. 
     By interposing the envelope detector  689  between the output of the audio amplifier  688  and the gate input of the MOSFET of the controllable attenuator  686  (as opposed to more directly coupling the output of the audio amplifier  688  to that gate input), the controllable attenuator  686  is prevented from being caused to provide and cease to provide attenuation of the signal from the talk-through microphone with each positive peak that occurs in the output of the audio amplifier  688 . Instead, the controllable attenuator  686  is caused to provide attenuation in a more continuous manner throughout periods of time in which multiple peaks exceeding the predetermined threshold level of amplitude for the output of the audio amplifier  688  occur, and to cease providing attenuation only after such periods have passed (the threshold being set, at least partially, by the threshold voltage of the gate of the MOSFET of the controllable attenuator and the voltage drop of the forward bias voltage across the diode of the envelope detector  689  in the particular implementation of the envelope detector  689  that is shown). In causing the controllable attenuator  686  to behave in this manner, the time delay by which the envelope detector  689  responds to the occurrence of a peak (either an isolated peak or the first of multiple adjacent peaks) exceeding the predetermined threshold (also known as the “attack time”) is necessarily set by the resistance of the first resistor and the capacitance of the capacitor, as those skilled in RC circuits will readily recognize. Further, the time required for the capacitor to drain sufficiently that the MOSFET is no long provided with a voltage triggering attenuation (also known as the “decay time”) is necessarily set by the capacitance of the capacitor and the resistance of the second resistor. Thus, the choice of the capacitance of the capacitor and the resistances of the first and second resistors determine the behavior of the compressor function brought about by the cooperation of the envelope detector  689  and the controllable attenuator  686 . 
     The envelope detector  626  is formed from a combination of a diode, resistors and a capacitor coupled in a manner that is substantially similar to what has just been described of the envelope detector  689  (but, just as in the case of the envelope detector  689 , the envelope detector  626  may be implemented in any of a variety ways, including as an active circuit). However, instead of being employed to integrate peaks in the signal output by the audio amplifier  688 , the envelope detector  626  is employed to integrate peaks in the signal output by the communications microphone  125 , as received by the envelope detector  626  through the differential amplifier  625 . As previously discussed, it is considered a best practice to effect any coupling of one of the mic-low or mic-high conductors to ground only at the location of whatever communications-type audio device to which the headset  1000   a  is coupled through the connector(s)  490  (e.g., the audio device  9000 ). Thus, coupling the positive and negative inputs of the differential amplifier  625  to the mic-low and mic-high conductors enables whatever signal carried by them to be tapped without causing either of them to be coupled to ground at the location of the audio circuit  600  (taking advantage of the very high impedance of typical differential amplifiers). Still, as those skilled in the art will readily recognize, it is not inconceivable to use a single-ended variant of amplifier in place of the differential amplifier  625 , perhaps along with coupling the mic-low signal to ground within the audio circuit  600  while coupling the mic-high signal to the single-ended input of such an amplifier. 
     The output of the integration performed by the envelope detector  626  is coupled to a gain input of the voltage-controlled attenuator  687 , thereby allowing a signal representing an integration of peaks in signals representing audio detected by the communications microphone  125  to be employed to selectively reduce the gain of the signal representing sounds detected by the talk-through microphone  185  that is provided to the input of the audio amplifier  688 . It should be noted that although the use of an attenuator that is a separate and distinct component from the audio amplifier  688  to serve as the mechanism by which gain may be reduced under the control of the envelope detector  626  is depicted, other embodiments are possible in which the gain of the audio amplifier  688  is controllable and the envelope detector  626  is more directly coupled to the audio amplifier  688  (i.e., coupled in some manner to a gain control input of the audio amplifier  688 ) to employ the audio amplifier  688  to reduce gain. This depiction of a separate and distinct component to actually effect a reduction in gain has been done partially to make clear that it is a reduction in gain that is meant to be carried out under the control of the envelope detector  626 , and not an increase. 
     In this way, a linkage between differential signal activity occurring across the mic-low and mic-high conductors and a reduction of the gain of talk-through audio is formed such that when a user of the headset  1000   a  speaks, the gain of the signal representing sounds detected by the talk-through microphone  185  is reduced for a period of time that starts with an attack time and ends with a decay time that are at least partially controlled by the capacitance of the capacitor and the resistances of the resistors of the envelope detector  626 . Thus, an open-loop compressor is formed by the interaction between the envelope detector  626  and the voltage-controlled attenuator  687  to implement this linkage. This addresses the problem of a user of the headset  1000   a  hearing his own voice to a greater than normal degree through the talk-through functionality of the headset  1000   a  whenever the user speaks. As those familiar with the physiology and acoustics of human speech will readily recognize, it is normal for a person to hear their own speech sounds when they speak, partially as a result of vocal sounds being internally conveyed to their ears through the Eustachian tubes, bone conduction and conduction through other structures within the neck and head; and partially as a result of vocal sounds being carried in the air from the vicinity of their mouth to the vicinities of both of their ears (presuming that the entrances to their ear canals are not covered). However, although a user hearing themselves talk to such a degree is normal, it is very possible that the talk-through functionality of the headset  1000   a  may cause a user&#39;s own voice to be conveyed to their ears with an unnaturally high amplitude and/or altered in some other way that may be unpleasant and/or distracting, and which may mask other sounds that they desire to hear (e.g., another person&#39;s voice). 
     Further, depending on the placement of the talk-through microphone  185  relative to the vicinity of a user&#39;s mouth and/or how loudly they speak, it is possible that their own speech sounds may be detected by the talk-through microphone  185  as being sufficiently loud that amplification at a normal gain level by the audio amplifier  688  causes triggering of the compression function provided by the combination of the envelope detector  689  and the controllable attenuator  686 . Thus, instead of there being a problem of a user hearing their own voice to a degree that is unnaturally loud and/or in a manner that is unnatural in other ways through the talk-through functionality (as described above), there may be a problem of a user experiencing a momentary loss of talk-through functionality that lasts both while they are speaking and for the duration of the decay time of that compression function following the instant they cease speaking. Depending on the length of that decay time, this could actually impede a user having a conversation with someone else by causing the user to become unable to hear what the other person is saying whenever the user speaks and for some additional period of time (i.e., that decay time) after the user stops talking. In effect, for example, a user of the headset  1000   a  may ask someone else a question, but be unable to hear either themselves asking the question or at least the start of the other person&#39;s answer. By reducing the gain with which the signal representing sounds detected by the talk-through microphone  185  is provided to the audio amplifier  688  whenever the user speaks, talk-through functionality is maintained, but at a reduced gain level that both prevents the user from hearing their own voice at an unnaturally loud level and that also precludes the output of the audio amplifier  688  reaching an amplitude that triggers compression. 
     In order for the addition of the open-loop compressor formed by the combination of the envelope detector  626  and the voltage-controlled attenuator  687  to effectively prevent unwanted triggering of the closed-loop compressor formed by the combination of the envelope detector  689  and the controllable attenuator  686 , at least the attack time of the open-loop compressor formed by the combination of the envelop detector  626  and the voltage-controlled attenuator  687  must be shorter than the attack time of the closed-loop compressor formed by the combination of the envelop detector  689  and the controllable attenuator  686 . However, it is preferred that this open-loop compressor operate generally faster than this closed-loop compressor, and therefore, it is preferable that the decay time of this open-loop compressor is also shorter than the decay time of this closed-loop compressor. 
     Within the pulsed attenuator  680 , the input of the microphone amplifier  684  is coupled to the talk-through microphone  185  to tap signals from the talk-through microphone  185  representing sounds that it has detected as those signals are selectively conveyed to the controllable attenuator  686  through the analog switch  681 . As depicted, the input of the microphone amplifier  684  is not AC-coupled to the talk-through microphone  185  (as the input of the audio amplifier  688  is) through a capacitor, but other embodiments are possible in which it could be. The output of the microphone amplifier  684  is coupled to a capacitor that is further coupled both to a first input of the comparator  683  and to a resistor, with the resistor being further coupled to ground. The capacitor and resistor cooperate to form a high-pass filter to pass through only signals from the output of the microphone amplifier  684  that represent higher frequency sounds (i.e., sounds having a frequency greater than a specific predetermined frequency) to that first input of the comparator  683 . The second input of the comparator  683  is coupled to a voltage source that is further coupled to ground. The voltage source provides the comparator a reference voltage level against which to compare the voltage levels of signals provided to the comparator  683  by that high-pass filter. The output of the comparator  683  is coupled to the input of the retriggerable monostable multivibrator  682 , the output of which is coupled to the gate input of a MOSFET of the pulsed attenuator  680 . The MOSFET is further coupled to ground and to the control input of the analog switch  681  to selectively ground this control input of the analog switch  681  under the control of the output of the retriggerable monostable multivibrator  682 . Grounding of this control input of the analog switch  681  through the MOSFET causes opening of the analog switch  681 , thereby breaking the coupling of the signal output of the talk-through microphone  185  to the controllable attenuator  686  through the analog switch  681 . 
     The microphone amplifier  684 , the comparator  683 , the retriggerable monostable multivibrator  682  and still other components cooperate to monitor signals output by the talk-through microphone  185  and to control the analog switch  681  to selectively couple the talk-through microphone  185  to the input of the controllable attenuator  686  of the talk-through circuit  680 . Thus, the pulsed attenuator  680  is yet another circuit that acts on the audio signal received by the audio amplifier  688  from the talk-through microphone  185 . Somewhat like the compressor formed by the cooperation of the envelope detector  689  and the controllable attenuator  686 , the pulsed attenuator  680  monitors talk-through audio and acts in response to particular conditions detected in the signal representing the talk-through audio. However, the pulsed attenuator  680  acts more quickly than that compressor and in response to different conditions. Through use of the envelope detector  689  having attack and decay times chosen to integrate peaks in audio so as to avoid providing compression in response to each individual peak, that closed-loop compressor is caused to compress only talk-through audio having too high an amplitude of multiple peaks in duration, and therefore, is unable to respond quickly enough to specific characteristics of a single peak (positive and/or negative) of sound detected by the talk-through microphone  185  to avoid allowing that single peak to be amplified by the audio amplifier  688  and passed on in its entirety to an ear of a user of the headset  1000   a.    
     The pulsed attenuator  680  addresses this insufficiency through the use of the high-pass filter formed by the resistor and the capacitor that are coupled to the first input of the comparator  683  to act as a differentiator with resistance and capacitance values selected to enable detection of the onset of a single peak in which the onset has a relatively fast rate of change in voltage level that exceeds a predetermined rate. Additionally, the comparator  683  detects when the voltage level of such an onset has also exceeded a predetermined voltage level. In particular, this depicted version of a differentiator combined with a comparator in the manner depicted forms a differentiator and comparator combination that detects the onset of positive peaks (not negative peaks) with a relatively fast rise time (not a relatively fast rate of negative-going change in voltage level). In this use of this differentiation and comparison, a presumption is made that a peak having an onset that has both a relatively fast rise time that exceeds the predetermined rise time and a voltage level that exceeds the predetermined voltage level will be a peak that will ultimately reach an amplitude (i.e., a voltage level) that is undesirably high. In other words, while the envelope detector  689  integrates peaks to enable detection and compression of a longer period event of higher amplitude than is desirable (thus requiring multiple peaks of undesirably high amplitude to have occurred before detection occurs), this combination of differentiator and comparator detects the onset of what appears likely to be a peak that will reach an undesirably high amplitude to enable action to be taken before it actually does so. In essence, the pulsed attenuator  680  attempts to predict such a peak to enable a preemptive response. 
     Again, it should be pointed out that other variants of differentiator and comparator circuits are possible that, either in lieu of or in addition to detecting the onsets of such positive peaks, would detect the onset of a negative peak having a relatively fast rate of negative-going change in voltage level and where the voltage level exceeds the magnitude of a predetermined negative voltage level. Thus, this illustration of this depicted variant of pulsed attenuator  680  should be seen as only one example implementation, and it may be deemed more desirable in some situations to implement a form of the pulsed attenuator  680  that responds to the onset of either positive or negative peaks of undesirably high amplitude (i.e., peaks ultimately achieving undesirably high magnitudes of voltage levels that are either positive or negative voltage levels) by detecting a high rate of change in voltage level that exceeds a predetermined rate of change without regard to whether it is a negative-going or positive-going rate of change and by detecting the exceeding of a predetermined level of voltage relative to a reference ground level without regard to whether it is a positive or negative voltage level. 
     In the implementation of the pulsed attenuator  680  that is depicted, the response to detecting what appears to be the onset of such a (positive) peak is a momentary disconnection (effectively momentary compression down to a zero or near-zero amplitude) of the signal output by the talk-through microphone  185  from the controllable attenuator  686  (and thus, ultimately a momentary disconnection of the talk-through microphone  185  from the input of the audio amplifier  688 ) to prevent such a predicted (positive) peak from ever being conveyed to the audio amplifier  688  such that it can never be passed on to an ear of a user of the headset  1000   a . However, it should be noted that other implementations of the pulsed attenuator  680  are possible in which the response is momentary compression to a lesser extent such that the predicted (positive) peak is able to be heard at an amplitude within a predetermined limit, rather than momentary disconnection (i.e., momentary compression down to a zero or near-zero amplitude). 
     However the pulsed attenuator  680  is actually implemented (e.g., whether it detects the onset of only one or both positive and negative peaks), whatever components are used in implementing the pulsed attenuator  680  are preferably chosen to be quick enough in their operation that the analog switch  681  (or its equivalent in other implementations) will be operated quickly enough to prevent a predicted peak from being conveyed through to the input of the audio amplifier  688 . Thus, it is preferred that the pulsed attenuator  680  have what might be called an “attack time” that is relatively fast, especially in comparison to the attack time of the compressor formed by the cooperation of the envelope detector  689  and the controllable attenuator  686 . The duration of the momentary disconnection (or compression to a lesser degree in other possible implementations) is determined by the period of time to which the retriggerable monostable multivibrator  682  (or its equivalent in other implementations) is set to drive the gate of the MOSFET with a signal that will cause the MOSFET to operate the analog switch  681  to be open to break the coupling of the talk-through microphone  185  to the controllable attenuator  686 . The retriggerable monostable multivibrator  682  is preferably set to a predetermined period of time selected to closely match the expected duration of at least one variety of the peaks that are expected to arise from sounds expected to be detected by the talk-through microphone  185  and that are desired to be blocked. It is desired that the pulsed attenuator  680  act to block little more than an individual one of such peaks from reaching the audio amplifier  688  to minimize the disruption in conveying other talk-through audio sounds from the talk-through microphone  185  to the audio amplifier  688 . Thus, it is also preferred that the pulsed attenuator  680  act with what might be called a “decay time” that is also relatively fast, again especially in comparison to the decay time of the compressor formed by the cooperation of the envelope detector  689  and the controllable attenuator  686 . Ultimately, the intention is that a user of the headset  1000   a  is able to listen to another person through the talk-through microphone  185 , and experience only the briefest interruption in hearing the other person that is necessary to prevent a sound having a peak of undesirably high amplitude from being conveyed to an ear of the user via the audio amplifier  688  and the acoustic driver  115 . 
     Indeed, similarly to the envelope detector  626  being previously discussed as preferably having attack and decay times that are faster than those of the envelope detector  689  so as to act to prevent a user&#39;s own voice sounds from possibly triggering compression (by the cooperation of the envelope detector  689  with the controllable attenuator  686 ), it is preferred that the attack and decay times of the pulsed attenuator  680  also be fast enough to similarly prevent triggering of compression by a sound detected by the talk-through microphone  185  having little more than a single peak of undesirably high amplitude (i.e., a peak predicted to reach an undesirably high positive and/or negative magnitude). In other words, just as it is desired that such a peak of such a sound never reach the audio amplifier  688  so as to avoid it being amplified and passed on to an ear of a user, it is also desired that such a peak of such a sound never reach the audio amplifier  688  so as to avoid having an amplified form of that peak reach the envelope detector  689  and charge the capacitor therein sufficiently to trigger compression. Without incorporating the pulsed attenuator  680 , the possibility exists that a sound having a single peak of undesirably high amplitude may be detected by the talk-through microphone, then amplified by the audio amplifier  688  and then acoustically output by the acoustic driver  115  to a user&#39;s ear before the compressor formed by the cooperation of the envelope detector  689  and the controllable attenuator  686  can respond, but be of high enough amplitude that the capacitor of the envelope detector  689  is charged sufficiently by the single pulse to trigger compression such that the user is deprived of talk-through functionality for the period of time dictated by the attack and decay times of the envelope detector  689 —a result that would provide the user with no protection from that peak in the talk-through sound and additionally render the user incapable of hearing what others nearby are saying for a brief time after that peak. 
     One specific application of the headset  1000   a  that is contemplated is by infantry personnel in a battlefield setting where gunshot and explosion sounds are expected. Of particular concern is when an infantryman using the headset  1000   a  fires his own gun. While the communications microphone  125 , being a noise-canceling microphone as previously discussed, will tend to reject the sound of the gunshot from that user&#39;s own gun, the talk-through microphone  185  will not do so. Analysis of typical gunshot sounds reveals that they are made up of an initial peak of very high amplitude followed by subsequent peaks of greatly diminished amplitude (i.e., there is a high rate of decay in amplitude following that initial peak) such that it is the initial high amplitude peak that poses the greatest concern. The compressor formed by the cooperation of the envelope detector  689  and the controllable attenuator  686  will respond sufficiently slowly that such a peak will be allowed to be conveyed from the talk-through microphone  185  through the audio amplifier  688  and to the acoustic driver  115  before compression can take place, and yet, such a peak will likely be of high enough amplitude to actually trigger compression of subsequent sounds (including sounds unrelated to the gun shot) for some period of time after such a peak. 
     However, with the pulsed attenuator  680  in place, the onset of that initial peak is received by the microphone amplifier  684  from the talk-through microphone  185 , and is amplified before being provided to the high-pass filter formed by the resistor and capacitor, and subsequently being provided to the comparator  683 . Presuming that the onset of that initial peak has a rate of change that exceeds the predetermined rate of change in voltage level, the high-pass filter allows the now-amplified onset of that initial peak to be conveyed to the first input of the comparator  683 , where it is compared to the predetermined voltage level as set by the reference voltage level provided at the second input of the comparator  683  by the reference voltage source. Presuming that the now-amplified onset of that initial peak exceeds the predetermined voltage level, the comparator  683  triggers the retriggerable monostable multivibrator  682 , causing it to drive the gate input of the MOSFET such that the MOSFET couples the control input of the analog switch  681  to ground for the predetermined period of time to which the retriggerable monostable multivibrator  682  has been set, thereby breaking the coupling of the talk-through microphone  185  ultimately to the input of the audio amplifier  688  for a period of time sufficient to prevent that initial peak from reaching the audio amplifier  688 . 
     As its name suggests, the retriggerable monostable multivibrator  682  is able to be “retriggered” such that the time period for which it is set to cause the analog switch  681  to open (through driving the MOSFET, as has been described) can be restarted in response to the detection of the onset of another peak that has the aforedescribed requisite characteristics before a currently occurring one of such time periods is over. Thus, if there is an instance of a first peak having the aforedescribed characteristics (e.g., an initial peak of a first gunshot sound) followed quickly enough by an instance of a second peak also having the aforedescribed characteristics (e.g., an initial peak of a second gunshot sound) such that the predetermined period of time of the retriggerable monostable multivibrator  682  acting in response to the onset of the first peak has not yet elapsed, then the predetermined period of time will be restarted amidst the currently occurring predetermined period of time in response to the onset of the second peak. As a result, the amount of time during which the retriggerable monostable multivibrator causes the analog switch  681  to break the coupling of the talk-through microphone  185  to the audio amplifier  688  is extendable so as to avoid allowing either a first peak or subsequent peaks to be conveyed to the input of the audio amplifier  688 . Although embodiments are possible in which the retriggerable monostable multivibrator  682  is replaced with some other form of timing device that is not retriggerable, it is preferred that a retriggerable form of timing device be used. Returning to the infantryman scenario, having a retriggerable form of timing device will allow the pulsed attenuator  680  to better accommodate the infantryman firing a “machine gun” or other fully automatic weapon that fires a stream of bullets in rapid succession such that there is a rapid succession of gunshot sounds, and thus, a rapid succession of sounds that each begin with such an initial peak of undesirably high amplitude. With the detection of the onset of each such peak, the retriggerable monostable multivibrator  682  is retriggered to repeatedly extend the period of time during which the retriggerable monostable multivibrator  682  causes the analog switch  681  (through the MOSFET) to remain open so as to prevent all of such peaks in the rapid succession of gunshot sounds from being conveyed to the input of the audio amplifier  688 . 
       FIG. 3  depicts portions of another possible variant of the electrical architecture  2000   a  introduced in  FIGS. 2 a  and 2 b   . This variant differs from the variant depicted in  FIGS. 2 a  and 2 b    to the extent that talk-through functionality is combined with ANR functionality. Again, for sake of clarity, components of the audio circuit  600  associated with only one of the earpieces  110  (and therefore, only one of the acoustic drivers  115 ) are depicted. Given the extensive treatment of numerous implementation details just provided with regard to  FIGS. 2 a  and 2 b   , such details are not repeated in  FIG. 3 , and therefore,  FIG. 3  presents a somewhat higher-level depiction. 
     As already depicted and discussed with regard to  FIG. 2 b   , the audio circuit  600  incorporates the differential amplifier  625 , pulsed attenuator  680 , talk-through circuit  685  and envelope detector  626 . However, as also depicted, and differing from what has been depicted and discussed with regard to  FIG. 2 b   , the audio circuit  600  further incorporates a summing node  615 , a pulsed attenuator  690  and an ANR circuit  695 . The pulsed attenuator  690  is coupled by its input to one of the feedforward microphones  195 , and is coupled by its output to the ANR circuit  695 . In turn, the ANR circuit  695 , like the talk-through circuit  685 , is coupled to the envelope detector  626  to receive the results of integrating an amplified form of signals representing sounds detected by the communications microphone  125 . Further, the summing node  615  is interposed between the acoustic driver  115  and the outputs of the talk-through circuit  685  and the ANR circuit  695  to combine these outputs into a single signal with which the acoustic driver  115  is driven. 
     As those familiar with ANR will readily recognize, both feedback-based and feedforward-based forms of ANR entail detecting unwanted noise sounds with one or more microphones, deriving anti-noise sounds and then acoustically outputting those anti-noise sounds at a location and with a timing selected to cause destructive acoustic interference with the unwanted noise sounds to at least reduce their acoustic amplitude. In embodiments in which the headset  1000   a  incorporates feedforward-based ANR, at least one of the feedforward microphones  195  is carried by a portion of the headset  1000   a  such that it is acoustically coupled to the environment external to the acoustic volumes enclosed by the earpieces  110  in the vicinity of an ear in order to detect unwanted noise sounds in that external environment. The ANR circuit  695  receives electrical signals representing the detected noise sounds, and employs those noise sounds as reference sounds from which to generate the anti-noise sounds provided to the acoustic driver  115  (through the summing node  615 ). 
     In a manner not unlike the previously discussed compression of signals received from the talk-through microphone  185  within the talk-through circuit  685  under the control of the envelope detector  626 , the ANR circuit  695  similarly compresses signals received from the feedforward microphone  195  under the control of the envelope detector  626 . Reducing the gain of the signal representing noise sounds detected by the feedforward microphone  195  in response to a user of the headset  1000   a  speaking may be deemed desirable, just as in the case of talk-through functionality, to avoid the conveyance of the user&#39;s own speech sounds to the user&#39;s own ears with an unnaturally high amplitude and/or with other unnaturally altered characteristics. Although it is commonplace for much of the range of frequencies of sound in which ANR is employed to be largely below the range of frequencies of sound normally associated with human speech, there is some degree of overlap between these two ranges. As a result, the speech sounds of a user of the communications headset  1000  (especially a user with a deeper voice) that are detected by the feedforward microphone  195  may be treated by the ANR circuit  695  as unwanted environmental noise sounds for which it generates anti-noise sounds that are caused to be acoustically output by the acoustic driver  115 . This acoustic output of anti-noise sounds meant to reduce lower frequency portions of their speech may produce undesirable acoustic artifacts that the user may find unpleasant or distracting. Reducing the gain of the signal representing noise sounds detected by the feedforward ANR microphone  195  as the user speaks preserves at least some degree of ANR functionality, while also reducing at least the amplitude of such speech-based anti-noise sounds. 
     Like the talk-through circuit  685  being coupled to the talk-through microphone  185  through the pulsed attenuator  680 , the ANR circuit  695  is coupled to the feedforward microphone  195  through the pulsed attenuator  690 . The pulsed attenuator  690  is preferably substantially identical to the pulsed attenuator  680 , and performs very much the same function. Although the ANR circuit  695  would attempt to employ a noise sound detected by the feedforward microphone  195  that includes a single undesirably high peak in amplitude to create an anti-noise sound, in so doing, the ANR circuit  695  may create a distorted anti-noise sound having its own undesirably high peak in amplitude in a failed attempt to counter the original noise sound. As those familiar with feedforward-based ANR will readily recognize, with sounds of sufficiently high amplitude, it is likely that the feedforward microphone  195  ceases to behave linearly, and thus, the attempt to create an anti-noise sound with such a high peak in amplitude is likely to actually create more noise. Further, not unlike the closed-loop compressor within the talk-through circuit  685 , it is believed likely that a corresponding compressor within the ANR circuit  695  would likely be unable to act quickly enough to prevent this from occurring. Hence the inclusion of the corresponding pulsed attenuator  690 . 
     It should be noted that although the talk-through microphone  185  and the feedforward ANR microphone  195  are depicted as being separate and distinct microphones, alternate embodiments are possible in which a shared microphone replaces both to provide a common sound detection input for both functions. This may be possible due to both the talk-through microphone  185  and the feedforward ANR microphone  195  being acoustically coupled to the external environment, and due to both preferably not being noise-canceling type microphones such that they are both indeed able to detect far-field sounds along with near-field sounds (unlike the communications microphone  125 , which as previously discussed, is a noise-canceling type of microphone structured to detect near-field sounds while largely ignoring far-field sounds). This depends, at least partially, on whether one or more locations exist on the structure of the communications headset at which a single microphone may be positioned (so as to be acoustically coupled to the external environment surrounding the headset  1000   a  and its user&#39;s head) that will allow detection of external sounds in a manner that will be effective for both functions. It should be further noted that were a single such microphone to be used, then it may be that only a single pulsed attenuator need interposed between that single microphone and both the talk-through circuit  685  and the ANR circuit  695 . 
     Again, it should be noted that only a single acoustic driver  115  and its associated circuitry within the audio circuit  600  (e.g., the talk-through circuit  685  and the ANR circuit  695 ) are depicted for sake of visual clarity. Thus, in embodiments of the communications headset  1000  having a pair of the earpieces  110 , there would be a pair of the acoustic drivers  115 , each having an associated one of a pair of the talk-through circuits  685  and an associated one of a pair of ANR circuits  695  coupled to it, and the single envelope detector  626  would be coupled to each of those talk-through circuits  685  and each one of those ANR circuits  695 . 
       FIGS. 4 a  and 4 b    provide depictions of an electrical architecture  2000   b  that may be employed by the headset  1000   b  of  FIG. 1 b   , and of a variant of the audio circuit  600  that may be employed within the electrical architecture  2000   b . What is depicted and the manner of its depiction in each of  FIGS. 4 a  and 4 b    are meant to be substantially analogous to  FIGS. 2 a  and 2 b   , respectively. Indeed, as depicted, the electrical architecture  2000   b  is substantially similar to the electrical architecture  2000   a , and in particular, many aspects of the audio circuit  600  in both architectures are substantially similar and function in substantially similar ways. However, a substantial difference of the electrical architecture  2000   b  from the electrical architecture  2000   a  is the lack of a communications microphone and other supporting components for implementing two-way communications in the electrical architecture  2000   b , reflecting the fact that the headset  2000   a  supports two-way audio communications, whereas the headset  2000   b  does not. Another substantial difference is that the control circuit  700  and the audio circuit  600  are co-located within the head assembly  100  in the headset  1000   b , thus eliminating the separate control box  300  and upper cable  200  of the headset  1000   a  in the headset  1000   b.    
     Thus, the mic-lo and mic-high conductors depicted as part of the electrical architecture  2000   a  in  FIGS. 2 a - b   , do not exist in the electrical architecture  2000   b , and are therefore not depicted in  FIGS. 4 a - b   . The pulsed attenuator  680  is depicted simply as a box in  FIG. 4 b    as it would likely be implemented substantially similarly to what was described with regard to  FIG. 2 b   . In contrast, the talk-through circuit  685  is depicted in more detail in  FIG. 4 b    to clearly depict is lack of the voltage-controlled attenuator  687  versus the variant of talk-through circuit  685  depicted in  FIG. 2   b.    
     Other embodiments and implementations are within the scope of the following claims and other claims to which the applicant may be entitled.