 |
Claims  |
|
|
What is claimed is:
1. A speech communications device having a transmit path, a receive path,
and a user-interactive control system for controlling device operating
parameters, said control system comprising:
means for dynamically suppressing background noise from an input speech
signal to produce noise suppression information;
means responsive to said noise suppression information for recognizing
user-spoken command words to produce device control data;
means responsive to said control data for controlling said device operating
parameters, and for producing device status data representing the
operating status of said speech communications device; and
means responsive to said status data for providing an indication to the
user as to the speech communications device operating status.
2. The speech communications device according to claim 1, wherein said
background noise suppressing means includes:
means for generating a noise-suppressed speech signal in response to said
noise suppression information; and
means for coupling said noise-suppressed speech signal to said speech
communications device transmit path.
3. The speech communications device according to claim 1, further
comprising means for placing a telephone call by voice command, the
placement of which constitutes one of said operating parameters.
4. The speech communications device according to claim 3, wherein said
controlling means includes:
directory means for storing a plurality of telephone numbers; and
dialing means for dialing telephone numbers obtained from said directory
means in response to recognition of a predetermined verbal command.
5. The speech communications device according to claim 4, further
comprising means for storing a telephone number in said directory means by
voice command, the storage of which constitutes one of said operating
parameters.
6. The speech communications device according to claim 1, wherein said
indication providing means is a speech synthesizer which synthesizes a
verbal reply based upon said device status data.
7. The speech communications device according to claim 1, wherein said
background noise suppressing means uses the spectral gain modification
noise suppression technique.
8. The speech communications device according to claim 1, further
comprising radio frequency (RF) communication means for transmitting
information carried by said transmit path and for receiving information
and for coupling said received information to said receive path.
9. A radio communications apparatus having a transmitter, a receiver, and a
speech-recognizing control system, said control system comprising:
means for dynamically suppressing background noise from an input speech
signal to produce noise suppression information;
means responsive to said noise suppression information for recognizing
user-spoken command words to produce voice command data;
means responsive to said voice command data for controlling operating
functions of said radio communications apparatus, and for producing voice
reply data indicative of the operating status of said radio communications
apparatus; and
means for synthesizing a speech reply signal from said voice reply data,
thereby providing an audible indication to the user as to the radio
communications apparatus operating status.
10. The radio communications apparatus according to claim 9, wherein said
radio communications apparatus is a mobile radiotelephone.
11. The radio communications apparatus according to claim 9, wherein said
background noise suppressing means includes:
means for generating a noise-suppressed speech signal in response to said
noise suppression information; and
means for coupling said noise-suppressed speech signal to said radio
communications apparatus transmitter.
12. The radio communications apparatus according to claim 10, further
comprising means for placing a telephone call by voice command, the
placement of which constitutes one of said operating functions.
13. The radio communications apparatus according to claim 12, wherein said
controlling means includes:
directory means for storing a plurality of telephone numbers; and
dialing means for dialing telephone numbers obtained from said directory
means in response to recognition of a predetermined verbal command.
14. The radio communications apparatus according to claim 13, further
comprising means for storing a telephone number in said directory means by
voice command, the storage of which constitutes one of said operating
functions.
15. The radio communications apparatus according to claim 9, wherein said
background noise suppressing means uses the spectral gain modification
noise suppression technique.
16. The radio communications apparatus according to claim 9, wherein said
noise suppression information includes channel-bank information and at
least one background noise estimate of said input speech signal.
17. The radio communications apparatus according to claim 9, further
comprising means for hands-free acoustic coupling said user-spoken command
words to said input speech signal, said speech reply signal to the user,
and an audio signal from said radio receiver to the user.
18. The radio communications apparatus according to claim 17, wherein said
hands-free acoustic coupling means is a speakerphone.
19. A radio transceiver having a transmitter, a receiver, and a hands-free
user control means for controlling a plurality of user-controlled radio
transceiver operating parameters upon a user-spoken command word, and for
providing audible feedback to the user as to the radio transceiver
operating status, said control means comprising:
first coupling means for providing hands-free acoustic coupling of
user-spoken input speech to said control means, thereby providing an input
speech signal;
means for dynamically suppressing background noise from said input speech
signal by spectral gain modification, thereby providing noise suppression
data;
means responsive to said noise suppression data for recognizing a plurality
of predetermined user-spoken command words to provide voice command data,
said plurality of predetermined command words corresponding to said
plurality of radio transceiver operating parameters;
means responsive to said voice command data for controlling said radio
transceiver operating parameters, and for producing radio status data
indicative of the present operating status of said radio transceiver;
means for synthesizing a speech reply signal from said radio status data;
and
second coupling means for providing hands-free acoustic coupling of said
speech reply signal from said control means to said user, thereby
providing audible feedback to the user as to said radio transceiver
present operating status.
20. The radio transceiver according to claim 19, wherein said radio
transceiver is a mobile radiotelephone.
21. The radio transceiver according to claim 19, wherein said background
noise suppressing means includes:
means for generating a noise-suppressed speech signal in response to said
noise suppression data; and
means for coupling said noise-suppressed speech signal to said radio
transmitter.
22. The radio transceiver according to claim 20, further comprising means
for placing a telephone call by voice command, the placement of which
constitutes one of said plurality of operating parameters.
23. The radio transceiver according to claim 22, wherein said controlling
means includes:
directory means for storing a plurality of telephone numbers; and
dialing means for dialing telephone numbers obtained from said directory
means in response to recognition of a predetermined verbal command.
24. The radio transceiver according to claim 23, further comprising means
for storing a telephone number in said directory means by voice command,
the storage of which constitutes one of said plurality of operating
parameters.
25. The radio transceiver according to claim 19, wherein said noise
suppression data includes channel-bank information and at least one
background noise estimate of said input speech signal.
26. The radio transceiver according to claim 19, further comprising third
coupling means for providing hands-free acoustic coupling of a received
signal from said radio receiver to said user.
27. The radio transceiver according to claim 26, wherein said first,
second, and third coupling means comprise a speakerphone.
28. The radio transceiver according to claim 19, wherein said radio
transceiver operating status includes information as to the names and
telephone numbers stored in said directory means, said status information
being user-accessible by voice command.
29. The method of controlling a radio communications apparatus having a
transmitter, a receiver, and a speech-recognizing control system,
comprising the steps of:
dynamically suppressing background noise from an input speech signal to
produce noise suppression information;
recognizing user-spoken command words in response to said noise suppression
information to produce voice command data;
controlling operating functions of said radio communications apparatus in
response to said voice command data, and producing voice reply data
indicative of the operating status of said radio communications apparatus;
and
synthesizing a speech reply signal from said voice reply data, thereby
providing an audible indication to the user as to the radio communications
apparatus operating status.
30. The method according to claim 29, wherein said radio communications
apparatus is a mobile radiotelephone.
31. The method according to claim 29, further comprising the steps of:
generating a noise-suppressed speech signal in response to said noise
suppression information; and
coupling said noise-suppressed speech signal to said radio communications
apparatus transmitter.
32. The method according to claim 30, wherein said operating functions
include placing a telephone call by voice command.
33. The method according to claim 32, further comprising the steps of:
storing a plurality of telephone numbers in a stored telephone number
directory; and
dialing telephone numbers obtained from said directory in response to
recognition of a predetermined verbal command.
34. The method according to claim 33, wherein said operating functions
further include storing a telephone number in said directory by voice
command.
35. The method according to claim 29, wherein said background noise
suppressing step uses the spectral gain modification noise suppression
technique.
36. The method according to claim 29, wherein said noise suppression
information includes channel-bank information and at least one background
noise estimate of said input speech signal.
37. The method according to claim 29, further comprising the steps of:
acoustically coupling said user-spoken command words to said input speech
signal;
acoustically coupling said speech reply signal to the user; and
acoustically coupling an audio signal from said radio receiver to the user.
38. The method according to claim 37, wherein said acoustic coupling steps
are performed by a speakerphone.
39. The method of controlling a radio transceiver having a transmit audio
path, a receive audio path, a plurality of operating parameters, and a
plurality of operating states, by speech recognition and speech reply,
comprising the steps of:
providing hands-free acoustic coupling of input speech spoken by a user to
said radio transceiver, thereby providing an input speech signal;
dynamically suppressing background noise from said input speech signal by
spectral gain modification, thereby providing noise suppression data;
recognizing a plurality of predetermined verbal command words in response
to said noise suppression data to provide voice command data, said
plurality of predetermined verbal command words corresponding to said
plurality of operating parameters;
controlling said radio transceiver operating parameters in response to said
voice command data, and producing radio status data indicative of the
present operating state of said radio transceiver;
synthesizing a speech reply signal from said radio status data; and
providing hands-free acoustic coupling of said speech reply signal from
said radio transceiver to said user, thereby producing audible feedback of
said present operating state of said radio transceiver.
40. The method according to claim 39, wherein said radio transceiver is a
mobile radiotelephone.
41. The method according to claim 39, further comprising the steps of:
generating a noise-suppressed speech signal in response to said noise
suppression data; and
coupling said noise-suppressed speech signal to said radio transmitter.
42. The method according to claim 40, wherein said plurality of operating
parameters includes placing a telephone call by voice command.
43. The method according to claim 42, further comprising the steps of:
storing a plurality of telephone numbers in a stored telephone number
directory; and
dialing telephone numbers obtained from said directory in response to
recognition of a predetermined verbal command.
44. The method according to claim 43, wherein said plurality of operating
parameters further includes storing a telephone number in said directory
by voice command.
45. The method according to claim 39, wherein said noise suppression data
includes channel-bank information, and at least one background noise
estimate of said input speech signal.
46. The method according to claim 39, further comprising the step of
providing hands-free acoustic coupling of a received signal from said
receive audio path to said user.
47. The method according to claim 46, wherein said acoustic coupling steps
are performed by a speakerphone.
48. The method according to claim 39, wherein said said radio transceiver
operating status includes information as to the names and telephone
numbers stored in said telephone number directory, said status information
being user-accessible by voice command. |
|
 |
|
 |
Claims |
|
|
|
Description |
|
|
BACKGROUND OF THE INVENITON
The present invention relates generally to speech recognition control
systems, and more particularly to a hands-free telephone control and
dialing system especially suited for use in a noisy environment such as
encountered in a vehicular radiotelephone application.
In both radio and landline telephone systems, the user typically
communicates by means of a handset that includes a speaker at one end
which is placed close to the user's ear, and a microphone at the other end
which is held close to the user's mouth. In operation, one hand of the
user is occupied holding the telephone handset in its proper orientation,
thereby leaving the user's only free hand to accomplish tasks such as
driving a vehicle. In order to provide a greater degree of freedom for the
user, speakerphones have commonly been used in landline telephone systems.
Recently, vehicular speakerphones (VSP's) have been developed for use in
automobiles. For example, U.S. Pat. No. 4,378,603 by Eastmond and U.S.
Pat. No. 4,400,584 by Vilmur, both assigned to the same Assignee as the
present invention, describe vehicular speakerphones with hands-free
operation.
Hands-free control systems which are responsive to human voice are
disclosed in a number of U.S. patents. U.S. Pat. No. 4,520,576 by Vander
Molen discloses a conversational voice command control system for a home
appliance such as a clothes dryer. The control system recognizes voice
commands and emits synthesized speech sounds, in an interaction with the
user, to obtain the information necessary for setting the operating
parameters. Speech recognition and speech synthesis have also been applied
to radio transceiver control functions (on/off, transmit/receive, volume
and squelch control, etc.) in U.S. Pat. No. 4,426,733 by Brenig.
Additionally, U.S. Pat. No. 4,348,550 by Pirz et al. discloses a repertory
dialing circuit for a telephone system which is controlled by the user's
spoken word.
However, the application of hands-free control to a vehicular speech
communications system, such as a mobile radiotelephone, introduces several
significant obstacles. When speech recognition is utilized in a vehicular
environment, the high degree of ambient noise inherent in a vehicle
presents a considerable problem to reliable voice control. Furthermore, a
vehicular speakerphone typically has a microphone that is distant from the
user's mouth, such as being mounted overhead on the automobile sun visor.
Consequently, the required high microphone sensitivity causes a large
increase in the amount of environmental background noise being applied to
the speech recognizer, as well as being transmitted to the landline party.
Numerous approaches to this noisy speech problem have been attempted, with
only limited success. For example, it is well known that speech may be
enhanced in an aircraft through the use of a separate microphone, located
at a distance away from the user's first microphone, such that it picks up
only background noise. The general characteristics of the background noise
can then be removed by subtracting an estimate of the background noise
from the desired signal. This technique has been shown to provide a
limited improvement in signal-to-noise ratio (SNR). However, it is very
difficult to achieve the required isolation of the second microphone from
the speech source while at the same time attempting to pick up the same
background noise environment as the first microphone.
A simple high-pass filter is often used, perhaps in a microphone
preamplifier, to reduce low frequency background noise. This may generally
be perceived as an improvement in voice quality, but does little to
improve the speech recognition process. Another approach, that of spectral
subtraction noise suppression, has typically been used as a noise
pre-processor to enhance the noise-degraded speech in preparation for
further processing by a bandwidth compression system such as a vocoder.
Although the aforementioned prior art techniques may perform adequately
under nominal background noise conditions, the performance of these
approaches become severely limited when used in specialized applications
such as vehicular speakerphones. The more distant microphone delivers a
much poorer signal-to-noise level to the land-end party due to road and
wind noise conditions. In rapidly-changing high noise automobile
environments, vehicular background noise may cause an automobile's speech
recognition control system to malfunction. Furthermore, the performance of
speakerphone audio switching circuitry may be significantly impaired in
such environments.
A need, therefore, exists for an improved hands-free control system for a
mobile radio transceiver that provides sufficient background noise
attenuation in high ambient noise environments.
SUMMARY OF THE INVENTION
Accordingly, it is a general object of the present invention to provide an
improved method and apparatus for controlling a speech communications
device in a noisy environment.
A more particular object of the present invention is to provide an improved
hands-free user-interactive control and dialing system for a mobile
radiotelephone.
A further object of the present invention is to improve the performance of
the radiotelephone's speech recognition control system, the voice quality
of the transmitted audio, and the audio switching operation of the
vehicular speakerphone.
In accordance with the present invention, an improved user-interactive
control system for a speech communications device is provided such that
the user's hands are free to accomplish other tasks. The control system of
the present invention includes a means for dynamically suppressing
background noise from an input speech signal; a means responsive to the
noise suppression means for recognizing user-spoken command words; a means
responsive to the speech recognition means for controlling operating
parameters of the speech communications device and for producing status
information representing the operating status of the device; and a means
responsive to such status information for providing an indication to the
user as to the speech communications device operating status.
In the preferred embodiment, the hands-free user-interactive control system
is used with a mobile radiotelephone employing a vehicular speakerphone.
User-spoken input speech is first acoustically coupled to the control
system, then noise-processed by a spectral subtraction noise suppressor.
The noise-processed speech information is then applied to a speech
recognizer which provides operating parameter control signals
corresponding to predetermined user-spoken command words. A
radio-interfacing control unit utilizes these control signals to dial
telephone numbers spoken by the user or recalled from a stored telephone
number directory in response to a corresponding command word, to store and
recall telephone numbers from this directory, and to control radio
functional operation. The control unit also provides status information to
a speech synthesizer which provides audible feedback to the user as to the
present operating status of the radiotelephone. Furthermore,
noise-suppressed speech is used by the vehicular speakerphone to improve
its switching performance, and used by the radio transmitter to improve
the quality of the transmitted speech.
BRIEF DESCRIPTION OF THE DRAWINGS
The features of the present invention which are believed to be novel are
set forth with particularity in the appended claims. The invention itself,
however, together with further objects and advantages thereof, may best be
understood by reference to the following description when taken in
conjunction with the accompanying drawings, in which:
FIG. 1 is a general block diagram of a speech communications device control
system according to the present invention;
FIG. 2 is a block diagram of the control system of the present invention
applied to a speech communications terminal;
FIG. 3 is a block diagram of a speech communications terminal control
system according to the present invention employing a hands-free
speakerphone; and
FIG. 4 is a detailed block diagram of an embodiment of the present
invention incorporating a mobile radiotelephone hands-free control system
with a vehicular speakerphone.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now to the accompanying drawings, FIG. 1 shows a general block
diagram of user-interactive control system 100 of the present invention.
Speech communications device 150 may include portions of any radio or
landline voice communications system, such as, for example, 2-way radio
systems, telephone systems, intercom systems, etc. User-spoken input
speech is applied to microphone 105, which acts as an acoustic coupler
providing an electrical input speech signal for the control system. Noise
processor 110 performs dynamic noise suppression upon the input speech
signal to provide noise suppression information to speech recognizer 120.
Dynamic noise suppression, as used herein, refers to the process of
adaptively filtering quasi-stationary background noise (i.e., noise
exhibiting a relatively constant long-term power spectrum) from the
desired signal. An example of dynamic noise suppression is the spectral
subtraction or spectral gain modification technique known in the art. The
noise suppression information may be comprised of either noise-suppressed
speech itself, spectral subtraction noise suppression parameters to be
used in the speech recognizer, or both. A further description of noise
processor 110, as well as the spectral subtraction/spectral gain
modification technique, may be found in the description of noise processor
410 of FIG. 4.
Speech recognizer 120 utilizes this noise suppression information by either
directly performing speech recognition upon noise-suppressed speech, or by
utilizing noise suppression parameters in the speech recognition process.
Hence, much more accurate speech recognition performance is achieved with
knowledge of the noise content of the speech signal. A further discussion
of an appropriate speech recognition apparatus, and how the preferred
embodiment incorporates noise suppression data into the speech recognizer,
may be found in the description accompanying FIG. 4.
Device controller 130 interfaces the control system to speech
communications device 150. Device controller 130 translates device control
data provided by speech recognizer 120 into control signals that can be
recognized by the particular speech communications device. These control
signals direct the device to perform specific operating functions as
instructed by the user. A example of a device controller known in the art
and suitable for use with the present invention is a microprocessor.
Device controller 130 also provides device status data representing the
operating status of speech communications device 150. This data is applied
to speech synthesizer 140, and translated into user-recognizable speech
when output via speaker 145. As will be apparent to those skilled in the
art, other means to provide an indication to the user as to the speech
communications device operating status may be utilized. Such indication
may include a visible display (LED, LCD, CRT, etc.) or a sound transducer
(tone generator or other audible signal). Thus, FIG. 1 illustrates how the
present invention provides a user-interactive control system utilizing
noise suppression, speech recognition, and speech synthesis to control the
operating parameters of a speech communications device.
FIG. 2 illustrates the application of the user-interactive control system
to a speech communications terminal, such as, for example, a telephone
terminal, a communications console, a 2-way radio, etc. Noise processor
210, speech recognizer 220, terminal controller 230, and speech
synthesizer 240, are the same in structure and operation as the
corresponding blocks of FIG. 1. However, control system 200 further
illustrates the internal structure of speech communications terminal 250.
In this embodiment, microphone 205 and speaker 295 are incorporated into
the speech communications terminal itself. A typical example of this
microphone/speaker arrangement would be a telephone handset. Speech
communications terminal 250 also has a transmitter block 260 coupled to a
transmit path 265, a receive block 280 coupled to a receive path 285, and
a terminal logic block 270 for controlling both the transmitter and
receiver blocks. Terminal logic block 270 typically has access to the
operating status information of speech communications terminal 250, and
interfaces this information to terminal controller 230 via terminal
interface path 235.
The example of a "smart" telephone terminal employing voice-controlled
dialing from a stored telephone number directory is now used to describe
the operation of the control system of the present invention. Initially,
the user speaks a verbal command into microphone 205, such as the command
word "recall". The utterance is first noise-processed by noise processor
210, then recognized as a valid user command by speech recognizer 220. In
this example, terminal controller 230 then directs speech synthesizer 240
to generate the verbal reply "name?" via speech synthesis output line 245
through multiplexer 290 to speaker 295. (For details of multiplexer 290,
refer to the description of multiplexer 470 of FIG. 4.) The user then
responds by speaking a word such as "office"--a name in the directory
index corresponding to a telephone number that he desires to dial. The
word will be recognized as a valid command word if it corresponds to a
predetermined name index stored in the terminal controller telephone
number directory. If valid, controller 230 directs speech synthesizer 240
to reply "office" thereby confirming the recognized command word.
The user then says the command word "send", which when recognized by the
control system, instructs terminal controller 230 to obtain the telephone
number corresponding to the name "office" and send telephone number
dialing information to terminal logic block 270 via terminal interface
path 235. Terminal logic block 270 outputs this dialing information along
transmit path 265 via transmitter 260. When the telephone connection is
made, terminal receiver 280 provides audio from receive path 285 to
speaker 295 via multiplexer 290. If a proper telephone connection cannot
be made, terminal controller 230 reads the status of terminal logic block
270 and generates status information, such as the reply word "busy", to be
output to the user via speech synthesizer 240. In this manner,
user-interactive voice-controlled directory dialing is achieved.
In addition to noise-processing operational commands, the user's speech is
also noise-processed before it is coupled to transmit path 265 via
transmit audio line 215. Hence, noise processor 210 provides noise
suppression information for the speech recognizer as well as a
noise-suppressed speech signal for the transmitter audio. Accordingly, the
performance of the control system's speech recognition process as well as
the quality of the transmitted audio signal are substantially improved.
Although speech recognition and speech synthesis allow a vehicle operator
to keep both eyes on the road, a conventional handset or hand-held
microphone prohibits him from keeping both hands on the steering wheel or
from executing proper manual (or automatic) transmission shifting. For
this reason, the control system of FIG. 3 incorporates a speakerphone to
provide hands-free control of the speech communications terminal. The
speakerphone performs the transmit/receive audio switching function, as
well as the received/reply audio multiplexing function.
Referring now to FIG. 3, control system 300 utilizes the same noise
processor block 310, speech recognizer block 320, terminal controller
block 330, speech synthesizer block 340 and speech communications terminal
350 as the corresponding blocks of FIG. 2. However, microphone 305 and
speaker 375 are not an integral part of the terminal 350. Instead,
speakerphone 360 directs input speech signal from microphone 305 to noise
processor 310 via input signal line 365. This input signal line may be
switched in the case of a simplex speakerphone, or may be directly coupled
in the case of a duplex speakerphone. Speakerphone 360 also controls the
multiplexing of speech reply line 345 and receive audio line 355 to
speaker 375. A more detailed description of the switching/multiplexing
configuration of the speakerphone is described later in conjunction with
FIG. 4.
Hence, FIG. 3 illustrates the application of the present invention control
system to a speech communications terminal employing a speakerphone to
free the user's hands. In the preferred embodiment, spectral subtraction
noise suppression is utilized to process the input speech for speech
recognition as well as for the transmitted audio path. A further
improvement to control system 300 may be realized by using
noise-suppressed speech for the speakerphone audio switching. In a high
noise environment, this technique provides a significant performance
increase to simplex vehicular speakerphones. Thus, the noise processing
block then performs three functions: improving speech recognition
performance; improving transmitted voice quality; and improving
speakerphone audio switching.
FIG. 4 is a detailed block diagram of the hands-free control system of the
present invention. In general, the control system arrangement is the same
as that of FIG. 3, with the above-mentioned exception that the input
speech signal from the microphone is first noise-processed before being
applied to the speakerphone. Microphone 402, which is typically
remotely-mounted at a distance from the user's mouth (i.e., on the
automobile sun visor), acoustically couples the user's voice to control
system 400. This speech signal is generally amplified by preamplifier 404
to provide input speech signal 405.
Noise processor block 410 first converts the analog input speech signal to
digital form at analog-to-digital converter 412. This digital data is then
applied to spectral subtraction noise suppressor 414, which performs the
actual dynamic noise suppression function. Any dynamic noise suppression
implementation may be utilized in block 414, however, the present
embodiment utilizes a particular form of spectral subtraction noise
suppression--the channel filter-bank technique. Under this approach, the
audio input signal spectrum is divided into individual spectral bands by a
bank of bandpass filters, and particular spectral bands are attenuated
according to their noise energy content.
The value of the attenuation is dependent upon the signal-to-noise ratio
(SNR) of the detected signal. The SNR | | |
