Our first stop in speech analysis is usually the short-time Fourier transform, or STFT1: Figure 1: Top: an STFT of speech (it's me, saying: "Es war einmal ein Mann"). Bottom: the signal's waveform. As we can see, this speech signal has a strong fundamental frequency track around 120 Hz, and harmonics at integer multiples of the fundamental frequency. We perceive the frequency of the fundamental as the speech's pitch. The magnitude of the harmonics varies over time, which we perceive as the so...| bastibe.de
A periodic signal has a harmonic spectrum. In the extreme case, a click train signal has a comb spectrum: Figure 1: A click train (left), and its corresponding comb spectrum (right). But why? After all, a solitary click has a uniform spectrum. So why should the sum of multiple clicks have a non-uniform spectrum? Figure 2: A click (left), and its corresponding spectrum (right). The answer exposes a lot of detail of how spectra work, and gives us a glimpse into the inner workings of spectral ph...| bastibe.de
Now that I am officially a failed scientist, I might as well talk about my research in public. I spent the last few years analyzing speech recordings. Particularly, voiced speech, where vibrations in the vocal folds excite resonances in the vocal tract, and a tonal sound leaves our mouths and noses. As humans, we are particularly tuned to recognizing these kinds of sounds. Even in loud background noise, even with dozens of people talking at the same time, we can clearly identify the sound of ...| bastibe.de