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Keyword Spotting Using Crosscorrelation. Presenters: Bathiya Senevirathna Roshan Rajeev Advisor : Dr. Uchechukwu Abanulo Montgomery College Speech Processing Laboratory. Presentation Outline. Research Goal Applications of Research Method Results Demo. Presenters:

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keyword spotting using crosscorrelation

Keyword Spotting Using Crosscorrelation

Presenters:

BathiyaSenevirathna

Roshan Rajeev

Advisor:

Dr. UchechukwuAbanulo

Montgomery College

Speech Processing

Laboratory

slide2

Presentation Outline

  • Research Goal
  • Applications of Research
  • Method
  • Results
  • Demo

Presenters:

BathiyaSenevirathna

Roshan Rajeev

Advisor:

Dr. UchechukwuAbanulo

Montgomery College

Speech Processing

Laboratory

slide3

Research Goal

Research Goal

Applications of Research

Method

Experiment

Demo

  • Keyword detection
    • Did the speaker say ____?
  • Keyword location
    • Where did the speaker say ____?
slide4

Research Goal

Applications of Research

Method

Experiment

Demo

  • Applications of Research
slide5

Research Goal

Research Goal

Applications of Research

Method

Experiment

Demo

  • Interactive Voice Response
    • Telephone ticket booking
  • National Security
    • Conversation monitoring to identify words of interest
slide6

Research Goal

Applications of Research

Method

Experiment

Demo

  • Method
slide7

Crosscorrelation

Research Goal

Applications of Research

Method

Experiment

Demo

  • Measure of similarity between two signals
  • Two signals compared by
    • Sliding one signal by a certain time lag
    • Multiplying both the overlapping regions
  • Repeating the process and adding the products until there is no more overlap
  • If both signals are exactly the same, there’s a maximum peak at the time = 0, and the rest of the correlation signals tapers off to zero

Area Overlap

slide8

Crosscorrelation

Research Goal

Applications of Research

Method

Experiment

Demo

slide9

Typical Cross-Correlation Results

Research Goal

Applications of Research

Method

Experiment

Demo

Keyword Match

No Match

See any differences??

slide10

A Closer look…

Keyword Match

Research Goal

Applications of Research

Method

Experiment

Demo

  • Much higher amplitude near zero-lag point
  • Rest of graph is almost zero

No Match

  • No clear maximum points
  • Amplitude is generally the same throughout
slide11

The Algorithm

Research Goal

Applications of Research

Method

Experiment

Demo

Find average of points in the first 10% of the samples

Find average of points in the last 90% of the samples

Compute the ratio of the two values. If n = the number of samples in the crosscorrelation graph:

Ratio =

slide12

The Algorithm

Research Goal

Applications of Research

Method

Experiment

Demo

1. Let the length of the keyword or phrase be n. The cross correlation of the keyword and the first n samples of the utterance is computed.

3. Shift observed portion by a small amount and repeat process

2. If a portion is reached where the calculated ratio is above a defined minimum threshold then mark the location of the indices

xcorr

slide13

Research Goal

Applications of Research

Method

Experiment

Demo

  • The Experiment
slide14

Experiment

Research Goal

Applications of Research

Method

Experiment

Demo

  • Effectiveness of the algorithm in finding keywords in a speech utterance
  • 8 speakers, mixed gender
  • Threshold varied from 6 to 15
  • Criteria:
    • Hit: >50% of keyword length found in correct location
    • False Alarm: 2 x length of keyword found in wrong location
slide15

Criteria - Hits

Research Goal

Applications of Research

Method

Experiment

Demo

Actual

Location

Wrong Location Miss!

<50% of Word Found Miss!

>50% of Word Found Hit!

slide16

Criteria – False Alarms

Research Goal

Applications of Research

Method

Experiment

Demo

Actual

Location (No Keyword)

>2x Keyword Length Found

False Alarm!

<2x Keyword Length Found

No False Alarm!

No Keyword Found

No False Alarm!

slide17

Results

Research Goal

Applications of Research

Method

Experiment

Demo

Performance of Algorithm at Different Threshold Levels

At a threshold of 8:

4/8 keywords were found

1/8 utterances with false alarms

slide18

Summary

Research Goal

Applications of Research

Method

Experiment

Demo

  • Crosscorrelation is a versatile tool for keyword spotting
  • This was just one example of a possible algorithm
  • Further research to optimize performance
slide19

Research Goal

Applications of Research

Method

Experiment

Demo

  • Demo