Abstract:
A user of a telecommunications terminal is made aware when the user&#39;s voice is disrupted by echo suppression, which notifies the user that he or she can adjust his or her speaking pattern, or move closer to the microphone in order to stop the clipping.

Description:
FIELD OF THE INVENTION 
     The present invention relates to telecommunications in general, and, more particularly, to telephone receiver interfaces. 
     BACKGROUND OF THE INVENTION 
     When a telecommunications terminal is used in speakerphone mode, acoustic echo or “feedback” between the loudspeaker and the microphone of the telecommunications terminal is likely to occur. When acoustic echo occurs, sound produced by the loudspeaker is sensed by the microphone and retransmitted back to its original source, causing undesirable artifacts, such as echo, to be heard. 
     In accordance with acoustic echo canceling, a digital-adaptive filter models the acoustic coupling between loudspeakers and the microphone of a telephone receiver (i.e., the “acoustic signature”) in the room. The audio signal that feeds the local loudspeaker is filtered using the acoustic signature stored in the adaptive filter model. This filtered signal is then subtracted from the microphone signal before the signal is transmitted to the far end, resulting in an improved signal under some conditions. However, acoustic echo canceling has some limitations. First, the adaptive filter might take several seconds to adapt to changes in the acoustic signature of the room. Second, adaptation can only occur when the far-end party is talking but the local parties are not. As a result, if changes to the room&#39;s acoustic signature occur during a conversation—for example, the microphone moves or a local party&#39;s body moves with respect to the local microphones—then the far-end party will hear the artifacts of inadequate cancellation until the digital filter can re-adapt. 
     Acoustic echo suppression is used to supplement the acoustic echo canceling when it is determined that the echo canceling is not sufficient to prevent acoustic echo. Acoustic echo suppression involves the insertion of mild attenuation in the microphone signal in order to prevent remaining echo signal from being transmitted. When echo suppression is used, the users of the telecommunications terminal often experience a “half-duplex” effect, where the speech of the speakerphone user is clipped or suppressed as a result of the echo suppression. When such clipping or suppression occurs, its cause is not readily apparent to the user of the telecommunications terminal, leading the user to become frustrated as he or she does not know when his or her speech is heard by the far-end participant nor does he or she know how to react in order to stop the voice clipping. 
     SUMMARY OF THE INVENTION 
     However, if the user of a telecommunications terminal is made aware when the user&#39;s voice is disrupted by echo suppression, the user can adjust his or her speaking pattern, or move closer to the microphone in order to stop the clipping. Therefore a need exists for a method for informing the users of telecommunications terminals when their voices are disrupted by the echo suppression of their terminal. 
     The present invention answers this need by providing a method for displaying an indication when the voice of a user of a telecommunications terminal is likely to be disrupted. Some embodiments of the present invention display an indication of the probability that the voice of the user is going to be disrupted, while others display an indication of the amount of echo suppression applied. The following disclosure teaches examples of the embodiments and their operation. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  depicts a schematic diagram of the salient components of the illustrative embodiment of the present invention. 
         FIG. 2  depicts a schematic diagram of the salient components of telecommunications terminal  101 . 
         FIG. 3  depicts a schematic diagram of the salient components of the illustrative embodiment of the present invention. 
         FIG. 4  depicts a flowchart of the salient tasks associated with the operation of an illustrative embodiment of the present invention as performed by telecommunications terminal  101 . 
     
    
    
     DETAILED DESCRIPTION 
     For the purposes of this disclosure, the term “disrupted,” and its inflected forms, is defined as clipped, suppressed, distorted, attenuated, or impaired. 
       FIG. 1  depicts a schematic diagram of the salient components of the illustrative embodiment of the present invention. The illustrative embodiment comprises telecommunication terminals  101  and  102  and telecommunications network  110 . 
     Telecommunications terminal  101  is a desk-set telephone receiver capable of operating in speakerphone mode. It will be clear to those skilled in the art, after reading this disclosure, how to make and use alternative embodiments of the present invention in which telecommunications terminal  101  is any type of communication device, such as, and without limitation, mobile telephone, two-way radio, and so forth. 
     Telecommunications terminal  102  is a desk-set telephone receiver capable of operating in speakerphone mode. It will be clear to those skilled in the art, after reading this disclosure, how to make and use alternative embodiments of the present invention in which telecommunications terminal  101  is any type of communication device, such as, and without limitation, mobile telephone, two-way radio, and so forth. 
     Telecommunications network  110  is used to transport signals between telecommunications terminal  101  and  102 . In accordance with the illustrative embodiment, telecommunications network  100  is the Public Switched Telephone Network, but it will be clear to those skilled in the art how to make and use alternative embodiments of the present invention in which telecommunications network  100  is another type of network, such as for example, and without limitation, the Internet. 
       FIG. 2  depicts a schematic diagram of the salient components of telecommunications terminal  101 . Telecommunications terminal  101  comprises headset  201 , button pad  202 , microphone  203 , loudspeaker  204 , and display  205 . 
     Headset  201  is a telephone headset. It will be clear to those skilled in the art how to make and use headset  201 . 
     Button pad  202  is a telephone button pad. It will be clear to those skilled in the art how to make and use button pad  202 . 
     Microphone  203  is an electro-acoustical transducer. Microphone  203  receives sounds from one or more telephone call participants and converts the sounds to electrical signals. It will be clear to those skilled in the art how to make and use microphone  203 . 
     Loudspeaker  204  is an electro-acoustical transducer that converts electrical signals to sound. It will be clear to those skilled in the art how to make and use loudspeaker  204 . 
     Display  205  is a light emitting diode (LED) that is set to emit red light when the amount of echo suppression inserted by telecommunications terminal  101  exceeds a predetermined threshold. In a similar fashion, display  205  is set to emit green light when the amount of echo suppression is below the predetermined threshold. It will be clear to those skilled in the art, after reading this disclosure, how to make and use alternative embodiments of the present invention in which display  205  is a loudspeaker, liquid crystal display, dial gauge, digital gauge, vibration device, etc. And still furthermore, it will be clear to those skilled in the art that, after reading this disclosure, the indication that the voice of user  301  is disrupted is displayed in a variety of ways, such as, and without limitation, by moving the needle on a gauge, by playing a sound, by triggering a tactile stimulus, such as vibration, and others. 
     Although, in the illustrative embodiment, display  205  can have two possible states—green or red, it will be clear to those skilled in the art how to make and use alternative embodiments of the present invention in which display  205  has a much larger number of states. Those skilled the in the art would recognize, that alternative embodiments can be devised in which, for example, display  205  is a liquid crystal display (LCD) capable of displaying ten-digit decimal numbers, a speaker capable of reproducing any sound pitch in the range 20 Hz to 20 kHz, etc. 
       FIG. 3  depicts a schematic diagram of the salient components of the illustrative embodiment of the present invention. It comprises loudspeaker signal  311 , echo signal  312 , voice signal  313 , and user  301 . 
     User  301  is a natural person using telecommunications terminal  101 . User  301  is acoustically co-located with terminal  101 . 
     Loudspeaker signal  311  is acoustic signal produced by loudspeaker  204 . Loudspeaker signal  311  deflects from the walls in the room where telecommunications terminal  101  is located and returns towards the terminal as echo signal  312 . 
     Echo signal  312  is the acoustic reflection of sound produced by loudspeaker  204  from the walls in the room where the telecommunications terminal is located. 
     Voice signal  313  is acoustic signal produced by user  301 . Voice signal  302  carries the speech of user  301 . 
       FIG. 4  depicts a flowchart of the salient tasks associated with the operation of the illustrative embodiment of the present invention. It will be clear to those skilled in the art, after reading this disclosure, how to perform the tasks associated with  FIG. 4  in a different order than represented or to perform the tasks simultaneously. 
     At task  401 , telecommunications terminal  101  receives signal from telecommunications terminal  102  and reproduces it through loudspeaker  204  as loudspeaker signal  311 . Loudspeaker signal  311  deflects from the walls in the room, where telecommunications terminal  101  is located, and returns to telecommunications terminal  101  as echo signal  312 . 
     At task  402 , telecommunications terminal  101  senses echo signal  312  and voice signal  313  with microphone  203 , and performs echo suppression to attenuate the echo signal in a well-known fashion. 
     At task  403 , telecommunications terminal  101  uses display  205  to display an indication that the voice of user  301  is disrupted. In the illustrative embodiment, display  205  is set to emit red light when the “echo return loss enhancement” (ERLE) of the echo cancelation falls below a predefined threshold. The threshold is 30 db, but it will be clear to those skilled in the art, after reading this disclosure, how to make and use alternative embodiments of the present invention in which the threshold has another value, such as, and without limitation, 10 dB, 20 dB, etc. When ERLE is poor, indicating the adaptive filter echo canceller is not sufficiently canceling echo, greater amounts of echo suppression are required to attenuate the echo residual otherwise transmitted to the far-end party; and, with greater amounts of suppression comes a higher likelihood of clipping the speakerphone user&#39;s speech. 
     In accordance with the illustrative embodiment, an indication of the relation between the echo return loss enhancement (ERLE) of the echo cancelation and a predefined threshold is displayed. However, it will be clear to those skilled in the art, after reading this disclosure, how to make and use alternative embodiments of the present invention in which a number N is displayed, wherein N is the magnitude of the echo return loss enhancement (ERLE), or a number that bears any mathematical relationship to the magnitude of the echo return loss enhancement (ERLE), such as linear, logarithmical, exponential, etc. It will also be clear to those skilled in the art, after reading this disclosure, that the value displayed by display  205  can be based on any other metric correlated with the amount of echo suppression inserted by telecommunications terminal  101 , such as, and without limitation, the power envelope of the incoming signal, the volume settings of loudspeaker  204 , “echo return loss” (ERL), etc. 
     At task  404  telecommunications terminal  102  determines the value of an indication of echo suppression inserted at telecommunications terminal  101 . In accordance with the illustrative embodiment, terminal  102  receives the value displayed by display  205  and reproduces it. However, it will be clear to those skilled in the art, how to make and use alternative embodiments of the present invention in which terminal  102  receives an indication of one or more metrics correlated with the amount of suppression applied by telecommunications terminal  101 , and determines independently whether to display an indication to the near-end party that the voice of user  301  is disrupted by telecommunications terminal  101 —in which case, task  404  becomes identical to task  403 . 
     It is to be understood that the disclosure teaches just examples of the illustrative embodiments and that many variations of the invention can easily be devised by those skilled in the art after reading this disclosure and that the scope of the present invention is to be determined by the following claims.