7

I have long felt that [f] and [s] are hard to tell apart on the phone, especially when spelling out words letter by letter. As a non linguist (but audio engineer) it seems to me that the frequencies required to distinguish them are usually higher than the bandwidth of the phone codec.

Today I fell foul of this in a most unfortunate way, and managed to get a parking penalty charge because the automated pay-by-phone system for the car park registered the wrong license plate.

In order to help me prepare the case to contest my parking ticket - can anyone provide me with a citation for this fact?

2
10

This paper may be useful for its collection of references. This paper is a single simple read. The problem is that the spectral properties of fricatives are usually reported in terms of the frequency of the spectral peak, where /f/ and /s/ are clearly different but also above the cutoff frequency for the phone. Another part of the black box that you're up against is that the ASR system doesn't involve a small, phonetically trained human making spectrograms, so you'd need to come up with a reason to think that the system they used has problems. (It isn't generally the case that nobody can distinguish [s] and [f] on the phone, and I think that some ASR systems introduce problems, so learning how ASR works could be helpful).

[EDIT]

The citation for the Jongman paper is Jongman, A., Wayland, R., & Wong, S. (1998). 'Acoustic characteristics of English fricatives: I. Static cues'. Working Papers of the Cornell Phonetics Laboratory. 12: 195-205. The current URL is http://conf.ling.cornell.edu/plab/paper/wpcpl12-Jongman.pdf.

3
  • 3
    +1. I would add that, while not all [s] and [f] sounds are ambiguous to humans on the phone all of the time, they are more likely to be confused in the very context in question--word-finally. See my answer to the related question linked in my comment above. – musicallinguist Apr 15 '15 at 2:27
  • 1
    Note, too, that in ordinary speech the context provides strong cues for distinction; for instance, it is hard to imagine a context in which sail and fail are equally likely. But reciting an arbitrary string of letters provides no context which might resolve an ambiguity. – StoneyB on hiatus Apr 15 '15 at 16:13
  • The second paper is no longer available. Can you provide a link to a different source? – tmh Dec 5 '15 at 18:17

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.