Frequency/harmonic analysis of accents

Question

I am looking to find out how accents could/would be detected by a programme, I haven’t as of yet undergone an experiment into detecting or observing anything noticeable about recorded accents. I am not sure a frequency/harmonic analyses will reveal anything. Trying to find any literature review on the subject is sadly lacking, so I was hoping to find out from the community where one might start or what would you look for in any given accent. Something quantifiable could or should surely be observed dependant on an accent?

For instance say I have 10 people from town A and 10 people from town B, all males with roughly the same age Town A and Town B both speak English but have different accents. If I ask each of them to repeat the same word, we should notice a difference in the frequency/harmonic analysis of Town B folk from Town A folk.

What is your best guess at where this could be found? Is frequency or harmonic analysis going to reveal anything between the two groups?

For instance if we take specific vowels we could possibly see a certain threshold reached in amplitude level and frequency (pitch) and could then work out the resonance frequencies of the vocal tract for certain accents based on key vowels? In speech science and phonetics the use of formant is used to mean an acoustic resonance of the human vocal tract. It is often measured as an amplitude peak in the frequency spectrum of the sound, using a spectrogram or a spectrum analyzer, though in vowels spoken with a high fundamental frequency, as in a female or child voice, the frequency of the resonance may lie between the widely-spread harmonics and hence no peak is visible.

If you notice that using a formant table you can construct vowels with a vocal formant filter, could this be reverse engineered to essentially "detect"?

My worst fear however is that any given vowel is going to have either a lack of accent specific information, or the analysis done will have too much sporadic information between individuals.

Could anyone point me in the right direction here im quite stuck?

Answer 1

I would guess that the most prevalent difference between accents (of the same language) is how the vowels are pronounced. Humans distinguish vowels mainly by the frequency of the formant, i.e. regions of high energy in the harmonic spectrum.

A good way to display this is the "formant map" which plots the frequency region of the second formant against the frequency region of the first. See for example: http://www.phy.davidson.edu/fachome/dmb/digitalspeech/formantmap.gif

In this 2D map every map has a specific region. For different accent the centroids of this regions probably shift around. That is certainly true for different languages. An interesting approach would be to measure this map for, say, an Australian vs. an American English speaker and look for systematic differences.