discrepancy between pitch traces and hearing impression

Inspired by JWL's comment to my two curves displayed in yesterday's blog post, I fed the sentence 'thirteen stairs we've got' into three different programmes (sorry for being old-fashioned in my spelling habits) in this order:

1. Wasp (downloadable from the web pages of UCL (= University College London))
2. SpeechAnalyzer (available from SIL Org.)
3. Praat (most phoneticians are familiar with the name at least).

Here are the results:

1.

2.

3.

After you've calculated the pitch in Praat you can extract the pitch and listen to it (the 'Hum-function').
Here it is, first the original sentence and then the 'hummed' version: