Method for increasing the voice recognition rate of a voice recognition calling device

A method for increasing the voice recognition rate in a voice recognition calling device wherein the frequencies of a ring sound are separated from those of a voice bandwidth to enable the application of input voice from a combined voice and ring input to a voice recognition processor. In an alternative embodiment, the duration of the ring sound is shortened to increase the voice recognition rate of a voice recognition calling device.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a voice recognition calling device, and in 
particular, to a method for increasing the voice recognition rate during 
call initiation. 
2. Description of the Related Art 
In general, a calling device such as a hands-free telephone provides the 
function of recognizing voice received through a speaker, processing the 
voice, and outputting voice through the speaker. Therefore, the speaker 
phone includes a speaker and a microphone, a voice recognition processor 
for recognizing voice received through the microphone, and a speaker phone 
processor for outputting the voice received through the microphone to the 
speaker. 
FIG. 1 is a block diagram of such a calling device, that is, a device for 
recognizing voice and enabling a call. This voice recognition calling 
device recognizes speech or voice, for example, "call", "open", "receive", 
and so on. The most common voice recognition calling device is a 
hands-free speaker phone. Another example of a voice recognition calling 
device is an automatic answering telephone. 
A voice recognition calling device receives rings from a switch as follows. 
First, when rings are transmitted from the switch, the voice recognition 
calling device generates rings as long as the rings are received. Here, 
when a user inputs a voice command such as "call", "open", or "receive" in 
voice, the voice recognition calling device recognizes the voice and 
switches to a speaker phone mode. Thus, the user can talk over the speaker 
phone. 
When the user wants to talk over the speaker phone, they must input a voice 
command while the calling device is ringing. Thus, the ring sounds are 
mixed with the voice command. Generally, voice recognition calling devices 
of this type are unable to receive the voice command in the mixed ring and 
voice command. Since the frequency of a ring sound generated in the 
general voice recognition calling device as shown in FIG. 1 typically has 
dual frequency of 500 Hz and 1 KHz in the same range as that of voice, and 
a single-second ring-on follows a two-second ring-off in its ring cycle. 
SUMMARY OF THE INVENTION 
An object of the present invention is to provide a voice processing method 
which can increase the voice recognition rate in a voice recognition 
calling device to allow rings to be received through a speaker phone. 
Another object of the present invention is to provide a voice processing 
method in a voice recognition calling device which can enable a call over 
a speaker phone upon the casual input of a voice command by the user. 
To achieve these and other objects, there is provided a voice processing 
method for enabling communication over a speaker phone in a voice 
recognition calling device. According to one embodiment of the method, a 
decrease in the recognition rate of voice received for initiating a call 
over a speaker phone is prevented by separating the frequency of a ring 
sound from that of the voice bandwidth. 
In another exemplary embodiment, the recognition rate of voice received for 
initializing a call over a speaker phone is increased by shortening the 
duration of the ring sound.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
Preferred embodiments of the present invention will be described in detail 
with reference to the attached drawings. Detailed description of related 
know function and structure will be avoided when it is deemed to obscure 
the subject matter of the present invention. Further, terms used in the 
description are defined in consideration of functions of the present 
invention. Thus, it should be contemplated that because the terms can be 
varied according to a user, a chip designer, or customary uses, the 
definition should be based on the overall disclosure of the present 
invention. 
FIGS. 2A and 2B are graphical representations of power vs. frequency for 
describing an input voice processing method for call initiation of a call 
over a speaker phone according to an embodiment of the present invention. 
Referring to FIGS. 1 and 2A and 2B, rings are generated by a ring generator 
22, and transmitted to a voice recognition processor 14 via a speaker SPK 
and a microphone MIC for a speaker phone. In the method, the bandwidth of 
voice filtered by a bandpass filter 12 is improved to minimize the amount 
of voice introduced into a ring sound. That is, the bandwidth of voice 
filtered by the bandpass filter 12 is set to 300 Hz to 1.5 kHz. The 
blocking frequency of the bandwidth of voice filtered by the conventional 
bandpass filter 12 was 3.4 kHz. From frequency analyses of actual voice, 
it is noted that most voice energy is distributed in a range of 400-900 Hz 
as shown in FIG. 2A. Therefore, at approximately 1.5 kHz or higher, 
frequency components of the voice frequency bandwidth may be blocked 
without any adverse result. 
In addition, the method provides for differentiating the frequency of a 
ring sound from that of the voice bandwidth, to block the ring sound 
reapplied via the microphone MIC from being introduced into the voice 
recognition processor 14. The frequency of the ring sound is made 
different from that of the voice bandwidth, by using a dual frequency of 
1.8 kHz and 2.2 kHz. This dual frequency exceeds the bandwidth range of 
the blocking frequency (i.e., 1.5 kHz) of bandpass filter 12. 
As a result of the frequency differentiation between the ring sound and the 
voice bandwidth, even when the ring sound is reapplied to the microphone 
MIC from the speaker SPK, the ring sound is output only through the 
speaker phone processor 18 and the speaker SPK without being applied to 
the voice recognition processor 14. Thus, even with the concurrent input 
of voice for a call over a speaker phone and a ring sound via the 
microphone MIC, only the voice for a speaker phone call is applied to the 
voice recognition processor 14. Therefore, controller 24 receives only the 
voice processed in the voice recognition processor 14, confirms the voice, 
and controls the speaker phone processor 18 to transmit a call to the 
speaker SPK thereby enabling a call through the speaker phone. 
FIGS. 3A and 3B are timing diagrams for describing an input voice 
processing method during call initiation for a call over a speaker phone 
according to another embodiment of the present invention. 
According to this embodiment, even with a single-second ring-on and 
two-second ring-off ring cycle (FIG. 3A), introduced from a switch, 
controller 24 applies a 0.5-second ring-on and 5.5-second ring-off ring 
cycle as shown in FIG. 3B. By generating a ring sound shorter than that 
output from the switch, (i.e., shortening the ring-on cycle), an area 
having a mixture of input voice and a ring, and which requires blocking 
recognition of the input voice can be removed. Therefore, a ring-induced 
decrease in voice recognition rate can be prevented. 
As described above, the present invention advantageously prevents the 
decrease of the input voice recognition rate for a call over a speaker 
phone by separating the frequency of a ring sound from that of voice 
bandwidth, or shortening the ring sound. 
While the present invention has been described with the specific 
embodiments, it is clearly understood that many variations can be made by 
anyone skilled in the art within the scope and spirit of the present 
invention. Thus, the appropriate scope hereof is deemed to be in 
accordance with the claims as set forth below.