Apparatus and methods for detecting onset of a signal

• US 6,240,381 B1
• Filed: 02/17/1998
• Issued: 05/29/2001
• Est. Priority Date: 02/17/1998
• Status: Expired due to Term

• Current Assignee: Fonix Corp.
• Original Assignee: Fonix Corp.
• Inventors: Newson, Michael W.
• Primary Examiner(s): Korzuch, William R.
• Assistant Examiner(s): Lerner, Martin
• Application Number:
  US09/024,152
• Time in Patent Office: 1,197 Days
• Field of Search: 704/210, 704/213, 704/215, 704/226, 704/227, 704/233, 704/248, 704/214, 704/236
• US Class Current: 704/214
• CPC Class Codes: G10L 25/93 Discriminating between voiced and unvoiced parts of speech signals G10L25/90 takes precedence

Abstract

The onset of a particular signal event is determined by first smoothing the signal containing the event, and then analyzing the smoothed waveform to determine onset. Smoothing is performed by analyzing the value of each point of data and modifying the value based on previous data point values in the waveform. The smoothed waveform is analyzed by iteratively stepping through the data points of the smoothed waveform and determining event onset based on change in data point values. The analysis uses the slope of the waveform to determine whether the data point values and slopes meet certain criteria indicating an event onset.

Claims

1. Apparatus for determining onset of an event, comprising:

receiver means for receiving a signal having a series of data points representing a physical event;

modifying means for forming a smoothed signal by selectively modifying a current data point in the series of data points, the modifying means comprising;

multiplication means for forming a multiplied value by multiplying a previous data point value by a predetermined value, wherein the multiplication means comprise scaling means for reducing a previous data point based on an amount of time between successive data points, and

addition means for adding the multiplied value to the current data point; and

onset detection means for analyzing the smoothed signal to determine a predetermined rate of signal change.

2. Apparatus for determining onset of an event, comprising:

receiver means for receiving a signal having a series of data points representing a physical event;

modifying means for forming a smoothed signal by selectively modifying a current data point in the series of data points, the modifying means comprising;

multiplication means for forming a multiplied value by multiplying a previous data point value by a predetermined value, wherein the multiplication means comprise scaling means for reducing a previous data point based on a sampling rate of the data points, and

addition means for adding the multiplied value to the current data point; and

onset detection means for analyzing the smoothed signal to determine a predetermined rate of signal change.

3. Apparatus for determining onset of an event, comprising:

receiver means for receiving a signal having a series of data points representing a physical event;

modifying means for forming a smoothed signal by selectively modifying a current data point in the series of data points, the modifying means comprising;

multiplication means for forming a multiplied value by multiplying a previous data point value by a predetermined value, wherein the multiplication means comprise means for reducing a previous data point by a decay factor determined according to the following equation;

$\mathrm{DecayFactor}=\text{\hspace{1em}<br><br>}<br><br>{<br><br>\mathrm{dB}<br><br>\left(\mathrm{DecayValue}\right)<br><br>}^{\frac{1}{\mathrm{Delay}\times <br><br>\mathrm{SampleRate}}},$

where Delay is the length of time for a signal to reach near zero when the Decay Factor is applied, dB (Decay Value) is Decay Value expressed in decibels, and Sample Rate is a rate at which the data points were sampled, and

addition means for adding the multiplied value to the current data point; and

onset detection means for analyzing the smoothed signal to determine a predetermined rate of signal change.

4. Apparatus for determining onset of an event, comprising:

receiver means for receiving a signal having a series of data points representing a physical event;

modifying means for forming a smoothed signal by selectively modifying a current data point in the series of data points, the modifying means comprising;

multiplication means for forming a multiplied value by multiplying a previous data point value by a predetermined value, and

addition means for adding the multiplied value to the current data point;

onset detection means for analyzing the smoothed signal to determine a predetermined rate of signal change further comprising;

boundary determination means for determining whether a current data point is within a predetermined data value range,

slope means, responsive to the boundary determination means, for determining a slope of a line segment associated with the current data point when the data point is outside the predetermined data value range, and

comparison means for comparing the slope of a line segment associated with the current data point with a slope of a line segment associated with a previous data point.

5. Apparatus for determining onset of an event, comprising:

receiver means for receiving a signal having a series of data points representing a physical event;

modifying means for forming a smoothed signal by selectively modifying a current data point in the series of data points, the modifying means comprising;

multiplication means for forming a multiplied value by multiplying a previous data point value by a predetermined value, and

addition means for adding the multiplied value to the current data point;

onset detection means for analyzing the smoothed signal to determine a predetermined rate of signal change further comprising;

boundary determination means for determining whether a current data point is within a predetermined data value range,

slope means, responsive to the boundary determination means, for determining a slope of a line segment associated with the current data point when the data point is outside the predetermined data value range,

limit determination means for maintaining a running average, and for determining the predetermined data value range by adding a range value to and subtracting a range value from the running average, and

means for determining the predetermined data value range having an upper limit equal to $\frac{\underset{k=0}{\overset{n}{\sum <br><br>}}<br><br>i_k}{n-1}\times <br><br>{10}^{-\text{\hspace{1em}<br><br>}<br><br>\frac{\sqrt{2}}{20}},\text{\hspace{1em}<br><br>}<br><br>\text{and <br><br> <br><br> <br><br>a <br><br> <br><br> <br><br>lower <br><br> <br><br> <br><br>limit <br><br> <br><br> <br><br>equal <br><br> <br><br>to}<br><br>\text{\hspace{1em}<br><br>}<br><br>\frac{\underset{k=0}{\overset{n}{\sum <br><br>}}<br><br>i_k}{n-1}\times <br><br>\frac{1}{{10}^{-\text{\hspace{1em}<br><br>}<br><br>\frac{\sqrt{2}}{20}}},$

where i_k equals the k^th data point I, and n represents the number of the data point being averaged.

6. A method for determining onset of an event, comprising the steps of:

receiving a signal having a series of data points representing a physical event;

forming a smoothed signal by selectively modifying a current data point in the series of data points, wherein the step of forming includes the substeps of;

multiplying a previous data point value by a predetermined value to form a multiplied value, wherein the substep of multiplying includes the substep of reducing a previous data point based on an amount of time between successive data points, and

adding the multiplied value to the current data point; and

analyzing the smoothed signal to determine a predetermined rate of signal change.

7. A method for determining onset of an event, comprising the steps of:

receiving a signal having a series of data points representing a physical event;

forming a smoothed signal by selectively modifying a current data point in the series of data points, wherein the step of forming includes the substeps of;

multiplying a previous data point value by a predetermined value to form a multiplied value, wherein the substep of multiplying includes the substep of reducing a previous data point based on a sampling rate used to obtain the data points, and

adding the multiplied value to the current data point; and

analyzing the smoothed signal to determine a predetermined rate of signal change.

8. A method for determining onset of an event, comprising the steps of:

receiving a signal having a series of data points representing a physical event;

forming a smoothed signal by selectively modifying a current data point in the series of data points, wherein the step of forming comprises the substeps of;

multiplying a previous data point value by a predetermined value to form a multiplied value, wherein the substep of reducing a data point includes the substeps of

reducing a previous data point by a decay factor determined according to the following equation;

$\mathrm{DecayFactor}=\text{\hspace{1em}<br><br>}<br><br>{<br><br>\mathrm{dB}<br><br>\left(\mathrm{DecayValue}\right)<br><br>}^{\frac{1}{\mathrm{Delay}\times <br><br>\mathrm{SampleRate}}},$

wherein Delay is the length of time for a signal to reach near zero when the Decay Factor is applied, dB (Decay Value) is Decay Value expressed in decibels, and Sample Rate is a rate at which the data points were sampled, and

adding the multiplied value to the current data point; and

analyzing the smoothed signal to determine a predetermined rate of signal change.

9. A method for determining onset of an event, comprising the steps of:

receiving a signal having a series of data points representing a physical event;

forming a smoothed signal by selectively modifying a current data point in the series of data points, wherein the step of forming comprises the substeps of;

multiplying a previous data point value by a predetermined value to form a multiplied value, and

adding the multiplied value to the current data point;

analyzing the smoothed signal to determine a predetermined rate of signal change, wherein the substep of analyzing comprises the substeps of;

determining whether a current data point is within a predetermined data value range, and

determining a slope of a line segment associated with the current data point when the data point is outside the predetermined data value range; and

comparing the slope of a line segment associated with the current data point with a slope of a line segment associated with a previous data point.

10. A method for determining onset of an event, comprising the steps of:

receiving a signal having a series of data points representing a physical event;

forming a smoothed signal by selectively modifying a current data point in the series of data points, wherein the step of forming comprises the substeps of;

multiplying a previous data point value by a predetermined value to form a multiplied value, and

adding the multiplied value to the current data point; and

analyzing the smoothed signal to determine a predetermined rate of signal change, wherein the substep of analyzing comprises the substeps of;

determining whether a current data point is within a predetermined data value range, and

determining a slope of a line segment associated with the current data point when the data point is outside the predetermined data value range;

maintaining a running average;

determining the predetermined data value range by adding a range value to and subtracting a range value from the running average; and

determining the predetermined data value range having an upper limit equal to $\frac{\underset{k=0}{\overset{n}{\sum <br><br>}}<br><br>i_k}{n-1}\times <br><br>{10}^{-\text{\hspace{1em}<br><br>}<br><br>\frac{\sqrt{2}}{20}},\text{and a lower limit equal to}<br><br>\text{\hspace{1em}<br><br>}<br><br>\frac{\underset{k=0}{\overset{n}{\sum <br><br>}}<br><br>i_k}{n-1}\times <br><br>\frac{1}{{10}^{-\text{\hspace{1em}<br><br>}<br><br>\frac{\sqrt{2}}{20}}},$

where i_k equals the k^th data point I, and n represents the number of the data point being averaged.

11. Computer readable media encoded with a method for determining onset of an event, comprising the steps of:

receiving a signal having a series of data points representing a physical event;

forming a smoothed signal by selectively modifying a current data point in the series of data points, wherein the step of forming comprises the substeps of;

multiplying a previous data point value by a predetermined value to form a multiplied value, wherein the substep of multiplying includes the substeps of

reducing a previous data point based on an amount of time between successive data points, and

adding the multiplied value to the current data point; and

analyzing the smoothed signal to determine a predetermined rate of signal change.

12. The media according to claim 11, wherein the substep of multiplying includes the substep of

reducing a previous data point based on a sampling rate used to obtain the data points.

13. Computer readable media encoded with a method for determining onset of an event, comprising the steps of:

receiving a signal having a series of data points representing a physical event;

forming a smoothed signal by selectively modifying a current data point in the series of data points, wherein the step of forming comprises the substeps of;

multiplying a previous data point value by a predetermined value to form a multiplied value, wherein the substep of multiplying includes the substep of

reducing a previous data point based on a sampling rate used to obtain the data points, and wherein the substep of reducing a data point includes the substep of

reducing a previous data point by a decay factor determined according to the following equation;

$\mathrm{DecayFactor}=\text{\hspace{1em}<br><br>}<br><br>{<br><br>\mathrm{dB}<br><br>\left(\mathrm{DecayValue}\right)<br><br>}^{\frac{1}{\mathrm{Delay}\times <br><br>\mathrm{SampleRate}}},$

wherein Delay is the length of time for a signal to reach near zero when the Decay Factor is applied, dB (Decay Value) is Decay Value expressed in decibels, and Sample Rate is a rate at which the data points were sampled, and

adding the multiplied value to the current data point; and

analyzing the smoothed signal to determine a predetermined rate of signal change.

14. Computer readable media encoded with a method for determining onset of an event, comprising the steps of:

receiving a signal having a series of data points representing a physical event;

forming a smoothed signal by selectively modifying a current data point in the series of data points, wherein the step of forming comprises the substeps of;

multiplying a previous data point value by a predetermined value to form a multiplied value, and

adding the multiplied value to the current data point;

analyzing the smoothed signal to determine a predetermined rate of signal change, wherein the step of analyzing includes the substeps of;

determining whether a current data point is within a predetermined data value range, and

determining a slope of a line segment associated with the current data point when the data point is outside the predetermined data value range; and

comparing the slope of a line segment associated with the current data point with a slope of a line segment associated with a previous data point.

15. Computer readable media encoded with a method for determining onset of an event, comprising the steps of:

receiving a signal having a series of data points representing a physical event;

forming a smoothed signal by selectively modifying a current data point in the series of data points, wherein the step of forming comprises the substeps of;

multiplying a previous data point value by a predetermined value to form a multiplied value, and

adding the multiplied value to the current data point;

analyzing the smoothed signal to determine a predetermined rate of signal change, wherein the step of analyzing includes the substeps of;

determining whether a current data point is within a predetermined data value range, and

determining a slope of a line segment associated with the current data point when the data point is outside the predetermined data value range;

maintaining a running average;

determining the predetermined data value range by adding a range value to and subtracting a range value from the running average; and

determining the predetermined data value range having an upper limit equal to $\frac{\underset{k=0}{\overset{n}{\sum <br><br>}}<br><br>i_k}{n-1}\times <br><br>{10}^{-\text{\hspace{1em}<br><br>}<br><br>\frac{\sqrt{2}}{20}},\text{and a lower limit equal to}<br><br>\text{\hspace{1em}<br><br>}<br><br>\frac{\underset{k=0}{\overset{n}{\sum <br><br>}}<br><br>i_k}{n-1}\times <br><br>\frac{1}{{10}^{-\text{\hspace{1em}<br><br>}<br><br>\frac{\sqrt{2}}{20}}},$

where i_k equals the k^h data point I, and n represents the number of the data points being averaged.

16. In a system which receives a signal representing a physical event, an apparatus for detecting onset, comprising:

receiver means for receiving a signal having a series of data points representing a physical event;

modifying means for forming a smoothed signal by selectively modifying a current data point in the series of data points, the modifying means comprising;

multiplication means for forming a multiplied value by multiplying a previous data point value by a predetermined value, wherein the multiplication means comprise

scaling means for reducing a previous data point based on an amount of time between successive data points, and

addition means for adding the multiplied value to the current data point; and

onset detection means for analyzing the smoothed signal to determine a predetermined rate of signal change.

17. In a system which receives a signal representing a physical event, an apparatus for detecting onset, comprising:

receiver means for receiving a signal having a series of data points representing a physical event;

modifying means for forming a smoothed signal by selectively modifying a current data point in the series of data points, the modifying means comprising;

multiplication means for forming a multiplied value by multiplying a previous data point value by a predetermined value, wherein the multiplication means comprise

scaling means for reducing a previous data point based on a sampling rate of the data points, and

addition means for adding the multiplied value to the current data point; and

onset detection means for analyzing the smoothed signal to determine a predetermined rate of signal change.

18. In a system which receives a signal representing a physical event, an apparatus for detecting onset, comprising:

receiver means for receiving a signal having a series of data points representing a physical event;

modifying means for forming a smoothed signal by selectively modifying a current data point in the series of data points, the modifying means including;

multiplication means for forming a multiplied value by multiplying a previous data point value by a predetermined value, wherein the multiplication means comprise

means for reducing a previous data point by a decay factor determined according to the following equation;

$\mathrm{DecayFactor}=\text{\hspace{1em}<br><br>}<br><br>{<br><br>\mathrm{dB}<br><br>\left(\mathrm{DecayValue}\right)<br><br>}^{\frac{1}{\mathrm{Delay}\times <br><br>\mathrm{SampleRate}}},$

where Delay is the length of time for a signal to reach near zero when the Decay Factor is applied, dB (Decay Value) is Decay Value expressed in decibels, and Sample Rate is a rate at which the data points were sampled, and

addition means for adding the multiplied value to the current data point; and

onset detection means for analyzing the smoothed signal to determine a predetermined rate of signal change.

19. In a system which receives a signal representing a physical event, an apparatus for detecting onset, comprising:

receiver means for receiving a signal having a series of data points representing a physical event;

modifying means for forming a smoothed signal by selectively modifying a current data point in the series of data points, the modifying means comprising;

multiplication means for forming a multiplied value by multiplying a previousdata point value by a predetermined value, and

addition means for adding the multiplied value to the current data point; and

onset detection means for analyzing the smoothed signal to determine a predetermined rate of signal change, wherein the onset detection means comprise

boundary determination means for determining whether a current data point is within a predetermined data value range,

slope means, responsive to the boundary determination means, for determining a slope of a line segment associated with the current data point when the data point is outside the predetermined data value range, and

comparison means for comparing the slope of a line segment associated with the current data point with a slope of a line segment associated with a previous data point.

20. In a system which receives a signal representing a physical event, an apparatus for detecting onset, comprising:

receiver means for receiving a signal having a series of data points representing a physical event;

modifying means for forming a smoothed signal by selectively modifying a current data point in the series of data points, the modifying means including;

multiplication means for forming a multiplied value by multiplying a previousdata point value by a predetermined value, and

addition means for adding the multiplied value to the current data point; and

onset detection means for analyzing the smoothed signal to determine a predetermined rate of signal change, wherein the onset detection means comprise

boundary determination means for determining whether a current data point is within a predetermined data value range;

slope means, responsive to the boundary determination means, for determining a slope of a line segment associated with the current data point when the data point is outside the predetermined data value range;

limit determination means for maintaining a running average, and for determining the predetermined data value range by adding a range value to and subtracting a range value from the running average, and

means for determining the predetermined data value range having an upper limit equal to $\frac{\underset{k=0}{\overset{n}{\sum <br><br>}}<br><br>i_k}{n-1}\times <br><br>{10}^{-\text{\hspace{1em}<br><br>}<br><br>\frac{\sqrt{2}}{20}},\text{and a lower limit equal to}<br><br>\text{\hspace{1em}<br><br>}<br><br>\frac{\underset{k=0}{\overset{n}{\sum <br><br>}}<br><br>i_k}{n-1}\times <br><br>\frac{1}{{10}^{-\text{\hspace{1em}<br><br>}<br><br>\frac{\sqrt{2}}{20}}},$

where i_k equals the k^th data point I, and n represents the number of the data points being averaged.