Reading 19

PaperLi, Wenzhe, and Tracy Anne Hammond. "Recognizing text through sound alone." Twenty-Fifth AAAI Conference on Artificial Intelligence. 2011.
Direct Link: http://www.aaai.org/ocs/index.php/AAAI/AAAI11/paper/download/3791/4119

Summary

 This paper presents a sound based algorithm for recognizing sketch. It is able to recognize 26 English alphabets. The main steps are

1) Noise Reduction : It performs two types of Endpoint noise removal. First by taking signal energy f first 150 ms and it represents noise. Each 45 ms frame is then calculated for mean energy. Other one calculates Gaussian probability function for the first 200 ms and then obtain parameters. If at least half of all the segments within the frame are valid, it is marked as valid else marked as silence. 

2) Normalization : Mean amplitude 

3) Feature extraction: Mean amplitudde, each frame is taken at 45 ms and size as 30 ms, along with overlapping. MFCC convert the fourier transform to logs of powers and then again back to signal.

3) Template matching: It uses dynamic time warping to calculate distance between query and template.

Discussion

This paper presents a very unique and innovative idea of using sound as a medium for recognizing sketches. This method if combined with other recognizers can be used for getting some good results. A little more explanation on what the feature set is, would have been better for understanding.