Abstract:
A measurement system and method combine an audio announcement system with a plurality of spaced apart sensors to evaluate intelligibility of audio output from loudspeakers of the audio announcement system. Processing can take place at some or all of the sensors as well as at a common control element. Evaluations can be based on use of an appropriate speech intelligibility index method.

Description:
FIELD OF THE INVENTION 
     The invention pertains to systems and methods of evaluating the quality of audible output provided to assist or inform individuals in a region. More particularly, the intelligibility of provided audio is evaluated by sensing a plurality of predetermined audible outputs, from an audio output transducer, and, evaluating intelligibility thereof on a per region basis. 
     BACKGROUND 
     It has been recognized that speech being projected or transmitted into a region is not necessarily intelligible merely because it is audible. In many instances such as sports stadiums, airports, public buildings and the like, speech delivered into a region may be loud enough to be heard but it may be unintelligible. Such considerations apply to audio announcement systems in general as well as those which are associated with fire safety, building or regional monitoring systems. 
     Relative to the latter, it has been known to conduct intelligibility testing in connection with such systems by having an installer or technician walk through a building or region being evaluated and listen to output from various speakers of the public address or alarm evacuation system to assess the intelligibility of the instructions or information being output by such devices. In an alternate mode, portable intelligibility analyzers can be carried through the building to each region of interest to provide a quantitative measure of speech intelligibility. 
     It also has been recognized that testing as described above requires that the installer or technician must literally move through most of the building or region being evaluated to listen or measure the intelligibility of speech signals being delivered in each region. This process is not only time consuming but expensive especially in large buildings. Additionally, when a floor or a portion of the region is being redecorated or built out for a different tenant, that portion of the building or region must be re-evaluated after the construction and/or build out has been completed. 
     It would be desirable to in some way make use of some or all of the existing equipment of such systems to improve intelligibility testing/evaluation. In such event, more frequent evaluation/testing could be conducted throughout the region or building monitored. 
     It also has been recognized that there is a benefit in moving from subjective evaluation of the intelligibility of speech in a region toward a more quantitative approach which, at the very least, provides a greater degree of repeatability. A standardized speech transmission index, STI, has been developed for use in evaluating speech intelligibility automatically and without any need for human interpretation of the speech intelligibility. 
     In STI-type of testing a noise or noise-like signal is amplitude modulated at various rates. The signal is transmitted from a source, such as a loud speaker, into a portion of a region of interest. The signals are detected, for example by a microphone. The received signals are analyzed by comparing the depth of modulation thereof with that of the test signal in each of the frequency bands. Reductions in modulation depth of received signals are associated with loss of intelligibility. 
     Details of STI-type evaluations have been published and are available for example in “The Modulation Transfer Function In Room Acoustics as a Predictor of Speech Intelligibility” by Steeneken and Houtgast, Acustica V28, PG66-73 (1973) and “A Review of the MTF Concept in Room Acoustics and its Use for Estimating Speech Intelligibility in Auditoria” by Steeneken and Houtgast, Institute for Perception TNO, Soesterberg, the Netherlands (1984). 
     The above described evaluation process can be carried out by any one of a variety of publicly available analysis programs as would be available to those of skill in the art. One such program has been disclosed and discussed in an article, “The Speech Transmission Index Program is Up and Running”, Lexington Center and School for the Deaf, V3.1 (Sep. 9, 2003). Other, earlier programs for evaluating STI are available as would be known to those of skill in the art. 
     There thus continues to be on ongoing need for improved, more efficient, intelligibility testing in connection with fire safety/evacuation systems. It would be desirable if the recognized benefits of Speech Transmission Index-type processing could be incorporated into such systems to improve intelligibility testing thereof. It would be also desirable to be able to incorporate such functional capability in a way that takes advantage of sensors which are intended to be distributed through a region being monitored so as to minimize additional installation cost and/or equipment needs. Preferably such functionality could not only be incorporated into the sensors being currently installed, but also could be cost effectively incorporated as upgrades in existing systems. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         FIG. 1  is a block diagram of a system in accordance with the invention; 
         FIG. 2A  is a block diagram illustrative of a module incorporating one or more ambient condition sensors and one or more microphones in accordance with the invention; 
         FIG. 2B  is a block diagram of an exemplary module incorporating one or more microphones in accordance with the invention; and 
         FIG. 2C  is a block diagram of an exemplary local processing module. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     While this invention is susceptible of an embodiment in many different forms, there are shown in the drawing and will be described herein in detail specific embodiments thereof with the understanding that the present disclosure is to be considered as an exemplification of the principals of the invention. It is not intended to limit the invention to the specific illustrated embodiments. 
     In accordance with the invention, intelligibility testing can be incorporated or embedded in hardware associated with audio announcement systems. In one embodiment, one or more microphones can be located throughout a region or building being evaluated. Circuitry associated with the respective microphones can carry out STI-type measurement processing of audio received from one or more speakers, which would be associated with building or regional audio announcement systems. 
     In one aspect, to carry out an intelligibility test, a sequence of STI test signals, Rapid Speech Transmission Index Test Signals, RASTI, or Speech Intelligibility Index, SII, test signals, ANSI standard S3.5-1997, are delivered from one or more loudspeakers. The received signals can be evaluated using STI-type processing, or any of the other available types of processing, locally at one or more of the microphones. Alternately, the signals can be coupled to a common location for analysis. 
     Where the analysis is conducted at least in part locally at the respective microphone or microphones, the calculated STI index or other index, can be transmitted either by cable or wirelessly to a control console for operator review and evaluation. Where the respective index values are inadequate, the operator can be notified using a graphical user interface or the like. 
     The system enables an operator, from a common control console, to test speech intelligibility throughout the building or region or only in certain zones at any given time. Additionally, regular testing can be scheduled and carried out automatically during off peak hours such as overnight, on weekends, and the like. 
       FIG. 1  illustrates a system  10 , which could be a fire alarm system of a known type usable for monitoring a region R. The system  10  includes common control circuitry or a fire alarm control panel  12 . The system  10  can include a plurality of ambient condition detectors  14 . The detectors  14  could for example be smoke detectors, thermal detectors or gas detectors or combinations thereof all without limitation. Those of skill in the art would understand the specific types of structures which are available to implement such detectors. Units such as unit  18 - i  represent local processing modules, discussed subsequently. 
     The detectors  14  are in communication with the control circuitry  12  via a wired or wireless medium indicated generally as  16 . In one embodiment, some of the detectors, such as  14 - 1 ,  14 - 3  and  14 - n  also include an audio transducer, such as a microphone or microphones indicated generally as  20 - 1 ,  20 - 3  and  20 - n . The microphones  20 - 1  . . .  20 - n  could be incorporated in only some or in all of the detectors  14 . 
     As discussed in more detail subsequently, signals received via microphones  20 - 1  . . .  20 - n  could be processed partially or completely at the respective detector  14 - 1  . . .  14 - n . Alternatively, some or all of the processing could be carried out at various system nodes or modules  18 - i  or at control circuitry  12 . It will be understood that signals from microphones  20 - 1  . . .  20 - n  could be transmitted in a variety of ways, via medium  16 , to control circuitry  12  all without limitation. 
     Region R can also incorporate an audio announcement system  30  which could be coupled to or be a part of the control circuitry  12 , indicated in phantom. The audio announcement system  30  incorporates one or more loud speakers  32 - 1  . . .  32 - m  located throughout the region R. The speakers  32 - 1  . . .  32 - m  could be used, as would be understood by those of skill in the art, for audibly outputting routine messages to people working or present in the region R. Alternately, the speakers  32 - 1  . . .  32 - m  could be used, in connection with system  10  to advise individuals in the region R of a hazardous condition, such as a fire or the like and provide information and instructions thereto. 
     System  30  also can include coupled thereto a one or more units  34  such as units  34 - 1  . . .  34 - k  located throughout the region R in addition to or in lieu of the detector(s)  14 . Units  34  can be coupled to system  30  and/or the alternative processing nodes by a wired or wireless medium  36 . Units  34  include one or more microphones  60 , such as microphone  60 - i    
     A source of test signals  40  could be coupled to audio announcement system  30  either acoustically or electrically, without limitation, to provide intelligibility test signals to be output via speakers  32  throughout the region R. The test signals could be, for example, STI-type test signals, RASTI, SII test signals, subsets thereof or other types of standardized test signals usable to evaluate intelligibility as would be understood by those of skill in the art. 
     In response to the output from the speakers  32 , microphones  20 ,  60 , receive audio input corresponding thereto based on their respective physical relationships with the members of the plurality  32 . The microphones  20 ,  60  could also be coupled to local processing circuitry such as units  18 - i  to formulate, at each location, an STI value, an RASTI value, an SII value or any other type of index value without limitation. 
     The respective index values can be determined at the respective microphone locations and transmitted via media such as medium  16  or  36  respectively to control circuits  12  and/or audio announcement system  30 . The respective indices can be presented, for example on or at graphical display  42  for review by operational personnel. Graphical display  42  may communicate with various parts of the system via wired or wireless connection. 
     Alternately, some or all of the index related processing could be carried out at control circuit  12  or system  30  without departing from the spirit and scope of the invention. In such an embodiment, signals from the microphones could be digitized and transmitted using a digital protocol to circuit  12  or system  30 . 
     The above described intelligibility testing process can be carried out automatically throughout the region R at any appropriate time and the results presented to the operation personnel subsequently. It also has the advantage that if the space in the region R is in part reconfigured, the process can be again initiated and carried out to determine or establish the intelligibility of audio throughout the revised portion of the region R. Additionally, because the testing involves interactions between audio from speakers  32  which is in turn sensed by microphones  20 ,  60  no operating personnel need travel through the region R as part of the test process. Finally, the speech intelligibility indices provide a quantitative assessment of intelligibility and eliminate any subjective influences which may be present where individuals are attempting to evaluate intelligibility based on their own perceptions. 
     It will also be understood that none of the exact details of the units or components such as detectors  14 ,  34 , local processing nodes or modules, such as module  18 - i , microphones  20 ,  60  or speakers  32  represent limitations of the present invention. Similarly, the numbers of such devices are also not limitations of the present invention. Finally, the location of the intelligibility index processing, which can in part be located at each of the respective detectors  14 , local processing node  18 , or, at the control circuits  12  or audio announcement system  30 , all without limitation, is not a limitation of the invention. 
       FIG. 2A , a block diagram illustrates additional details of a representative detector  14 - i  having a housing  48  which carries a microphone  20 - i  and provisions for connections to several optional external microphones such as microphones  20 - i′ . Housing  48  can be mounted on or adjacent to a selected surface in region R. Detector  14 - i  includes at least one ambient condition sensor  50  which could be implemented as a smoke sensor, a flame sensor, a thermal sensor, a gas sensor or a combination thereof. 
     Outputs from sensor  50  and microphone(s)  20 -,  20 - i′ , are coupled to control circuitry  52  which could be implemented, in part, with hard wired circuits or a processor for executing pre-configured instructions or logic  52   a . Instructions  52   a  could include processing instructions for establishing a speech intelligibility index, STI, RASTI, or SII, or subsets thereof, all without limitation in response to incoming audio sensed at microphone at  20 - i.    
     Outputs from circuits  52  can include indices indicative of outputs from sensor  50  as well as microphone  20 - i  or, the processed intelligibility indices in whatever form is preferred. Those outputs are coupled via interface circuitry  54  to wired or wireless medium  16  for transmission to control system or fire alarm control panel  12 . It will also be understood that the interface  54  can carry out bi-directional communication between the medium  16  and the detector  14 - i  if desired, all without limitation. 
       FIG. 2B  illustrates, in block diagram form, a member  34 - i  of the plurality  34 . Module  34 - i  includes a housing  58  which is mountable on a selected surface in the region R. Housing  58  may include a microphone, such as microphone  60 - i  and provisions for connections to several optional external microphones  60 - i′  which are in turn coupled to control circuits  62 . Circuits  62  could include both hard wired circuits and/or a processor for executing pre-stored instructions or logic  62   a , as desired, for carrying out speech intelligibility processing and producing an intelligibility index locally to the module  34 - i . The control circuits  62  can in turn transfer the generated intelligibility index, via interface circuit  64  and medium  36  to system  30  for analysis and presentation as desired on display  42 , for example. 
       FIG. 2C  is a block diagram of a local processing node or module  18 - i . Previously described components have been assigned the same identification numeral. The node or module  18 - i  could be coupled to either of media  16 ,  36  as desired. Local circuitry and software carry out speech index processing in response to received audio. The nodes or modules  18 -I could also carry out processing of signals received at other units such as units  14  or  34 . Control circuits  72 , which include software and/or other circuitry  72   a  process received audio and generate a quantitative output(s) as to quality thereof, as described above. They can communicate via interface circuits  74 . 
     It will be understood that the implementations illustrated for modules  14 - i  and  34 - i  are exemplary only. Variations can be incorporated therein, as would be understood by those of skill in the art, depending on the specific application all without departing from the spirit and scope of the present invention. Among other variations, the microphones are exemplary only. Other forms of audio input transducers come within the spirit and scope of the invention. 
     From the foregoing, it will be observed that numerous variations and modifications may be effected without departing from the spirit and scope of the invention. It is to be understood that no limitation with respect to the specific apparatus illustrated herein is intended or should be inferred. It is, of course, intended to cover by the appended claims all such modifications as fall within the scope of the claims.