Method and apparatus for voice detection having adaptive sensitivity
First Claim
1. A method of detecting voice energy, comprising the steps of:
- measuring a minimum energy level of an input signal for a predetermined time period in order to determine whether said input signal is a valid signal;
detecting in response to said input signal being a valid signal when the frequency of said input signal crosses a predetermined frequency boundary subsequent to the expiration of said predetermined time period; and
characterizing said input signal as voice responsive to said detecting step subsequent to the number of frequency crossings exceeding a predetermined threshold value.
3 Assignments
0 Petitions
Accused Products
Abstract
This invention enables voice energy to be distinguished from energy due to other sources such as telephone call progress signals. A portion of the audio spectrum is divided into a high and into a low frequency band and the energy content of these bands is examined. The audio energy of a signal is passed through a set of filters and compared. A frequency boundary crossing of an input signal subsequent to filtering is used to signify the receipt of a voice signal. By operating in this manner, voice, whose predominant frequency switches in a random fashion from being greater than to less than a cutoff frequency, can be distinguished from other signals either below or above the cutoff frequencies of the filters. The detection of voice energy is not begun until a predetermined threshold of energy has been received for a specified period of time. This specified period of time need not be continuous after a ringback signal is received. Subsequent to the receipt of a ringback signal, the voice detection mechanism will proceed as long as the total time above the threshold exceeds the specified time.
-
Citations
7 Claims
-
1. A method of detecting voice energy, comprising the steps of:
-
measuring a minimum energy level of an input signal for a predetermined time period in order to determine whether said input signal is a valid signal; detecting in response to said input signal being a valid signal when the frequency of said input signal crosses a predetermined frequency boundary subsequent to the expiration of said predetermined time period; and characterizing said input signal as voice responsive to said detecting step subsequent to the number of frequency crossings exceeding a predetermined threshold value.
-
-
2. A method of detecting voice energy, comprising the steps of:
-
measuring a minimum energy level of an input signal for a predetermined time period in order to determine whether said input signal is a valid signal; passing said valid input signal through a filter having a cutoff frequency; detecting when the frequency of said valid input signal crosses a predetermined frequency boundary, corresponding to the cutoff frequency of said filter, subsequent to the expiration of said predetermined time period; and
,characterizing said input as signal voice responsive to said detecting step subsequent to the number of frequency crossings exceeding a predetermined threshold value.
-
-
3. A system for detecting voice energy and for distinguishing said voice energy from voice and telephone ringback signals, comprising:
-
means for measuring a minimum energy level of an input signal for a predetermined time period in order to determine whether said input signal is a valid signal; means responsive to said measuring means for detecting a requency crossing of said valid input signal over a predetermined frequency boundary subsequent to the expiration of said predetermined time period; and
,means for detecting when the number of frequency crossing exceeds a predetermined threshold value, thereby characterizing said valid input signal as voice. - View Dependent Claims (4, 5, 6, 7)
-
Specification