Is it possible to have the same symbol for different sounds in IPA?

Question

It is said that in IPA, each symbol represents a unique sound. But on the Wikipedia page on the Voiceless Velar Fricative (/x/), I find these examples:

Hindustani 'ख़ुशी' /xuʃi:/ (sometimes खुशी, /kʰuʃi:/) and Assamese 'অসমীয়া' (/ɔxɔmija/).

I am a native Assamese speaker and I have learned Hindi in school for ten years, and I have been regularly conversing in it for years. To my ears, these sounds are similar but clearly distinct. Even in the audio clip that accompanies the article, I feel the first part is the Hindustani ख़ while the second part is the Assamese স. I asked my friends who too are fluent in both Assamese and Hindi and they too seem to agree.

But I understand that un-systematic intuitions like the ones me and my friends are having in this case would not count as good reason to assign different symbols.

I just wanted to know the reason: if these are the same sounds, why am I so easily able to distinguish between the two? And if they are actually different sounds, why has IPA assigned the same symbol to them?

Answer 1

Yes, this is not only possible but regular practice. In general, one only notates the kind of features of a sound that are relevant for the transcription and it is left to reader to add the omitted details. So when /x/ is realised differently in Hindi/Urdu and Assamese, it is assumed that the reader is aware of that difference and knows how to pronounce a Hindi /x/ or an Assamese /x/.

See also this question and its answers.

Answer 2

As jk mentioned, it's common to only transcribe the features that are relevant (a "broad" transcription). But there are a few other reasons why the mapping from symbol to sound might not be one-to-one.

First, transcriptions more often focus on phonemes (mental units representing sounds), not phones (the sounds themselves). And the naming of phonemes is pretty much arbitrary. Often they're named after phones that they correspond to, like how the English phoneme /t/ is often pronounced as the phone [t], but this isn't a hard-and-fast rule; sometimes they're given non-IPA names, like the use of ḥ in transcribing Semitic languages or ь in Slavic, and sometimes they're just given algebraic symbols, like *h₁, *h₂, and *h₃ in discussions of Proto-Indo-European. And when this happens, it doesn't necessarily mean that Arabic ḥ and Hebrew ḥ are actually pronounced the same.

Second, while the IPA provides a lot of diacritics for more precision, it also has a principle of not distinguishing sounds that aren't phonemically different in any language. This is why, for example, many voiced fricatives aren't distinguished from the corresponding approximants, and why there aren't different symbols for taps versus flaps. There's simply no known language that has a phonemic contrast between taps and flaps.

Answer 3

To add, "in IPA, each symbol represents a unique sound" is not true even in non-phonemic transcriptions. The current Principles of the International Phonetic Association states:

The IPA is designed to be a set of symbols for representing all the possible sounds of the world's languages. The representation of these sounds uses a set of phonetic categories which describe how each sound is made. These categories define a number of natural classes of sounds that operate in phonological rules and historical sound changes. The symbols of the IPA are shorthand ways of indicating certain intersections of these categories. Thus [p] is a shorthand way of designating the intersection of the categories voiceless, bilabial, and plosive; [m] is the intersection of the categories voiced, bilabial, and nasal; and so on. The sounds that are represented by the symbols are primarily those that serve to distinguish one word from another in a language.

Also consider this passage from the Handbook of the IPA (1999: 29):

If the relevant phonological system is known, a transcription can be devised which includes any number of additional symbols to indicate the phonetic realizations of the phonemes. ... Narrowness is regarded as a continuum, so that [tʃɛkðəlɛnzwɛɫ] might be regarded as a slightly narrow (or 'narrowed') transcription, and [tʃe̞ʔ͡kð̞əlɛ̃nzwæ̠ɫ] as very narrow.

(both my emphasis)