Lecture 34 Blog, ECE438 Fall 2010, Prof. Boutin

Friday November 12, 2010 (Week 12) - See Course Outline.

We began the lecture by discussing the students solution of the homework assignment, in which they were supposed to determine whether Neil Armstrong said "for man" or "for a man" when he stepped foot on the moon. Some people tried the upsampling+filtering approach in order to increase the resolution of the signal. Unfortunately, no one reported being able to hear the "a" sound with that approach. The second approach that was discussed was the formant comparison approach. The main difficulty with that approach is to determine the formants of the appropriate "a" sound to compare with. Some students used formant tables from the literature, some students tried to obtained the formants directly from words, in some cases directly from the speech sound of Neil Armstrong. The third approach that was discussed is to compare the "for man" part of the sound with the "for mankind" part of the sound, the idea being that if the signal between "for" and "man" in "for man" does not contain an "a", then it should be very similar (from the frequency domain point of view) to the signal between "for" and "man-" in "for mankind". Although the person who used that approach was not able to conclude definitively, I find this a very clever and original approach.

I am hoping several students will share their report on Rhea!

We continued with a discussion of wide-band and narrow-band spectrograms, looking at two illustrations from this document by Mike Brookes (the "my" sound, and the arpegio). Notice the constant formant frequencies in the wideband spectrum! We finished the lecture by giving a filtering view of the short-time Fourier transform, the proof of which will be given in the next lecture.

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