Voiced vs Voiceless or Why does b sound like p but not really?

This is where it would pay to have grown up speaking Cantonese, Vietnamese or Navajo ... One thing that can be said about all languages is that they all maintain sound contrasts, that is, have a set of sounds which can even intuitively be divided into groups. Say a hypothetical language has the sounds tt, b, g, kk, d, pp, k, t, p and you were asked to put them into "similar" groups - how would you order them? Most likely you will come up with three groups b, p, pp; d, t, tt and g, k, kk. In this case linguists would talk about b p pp contrasting with each other and you would have a good chance to find word contrasts like baka, paka and ppaka in such a language. So what on earth does this have to do with Gaelic? Patience ...

English also has such contrasts: b p, d t and g k e.g in words like bat vs pat, down vs town and got vs cot ... Now, sit back for a moment and think about what your mouth is doing when you are saying these words. Put your hand on your throat (feel free to close the study door before trying this) and say them again. You should notice that with b d g there is something vibrating in your throat, whereas there is no vibration with p t k. This is due to two ligaments (bits of anatomy) in your throat called the vocal chords which either vibrate or do not vibrate during speaking. If they are vibrating, we talk about a voiced sound, if they are not, we call it a voiceless sound.

So we say that English has a major contrast between voiced and voiceless sounds - the distinction that keeps people from worrying when you start talking about 'patting your sister' as opposed to 'batting' her. BUT ... not all languages make this particular contrast. Some languages like Cantonese only have voiceless stops. So how then can Cantonese people maintain these contrasts you may ask? Simple ... instead of relying on the voiced/voiceless cue, these languages use aspiration, that is, the difference is signalled by the lack or the presence of a puff of air after the sound. Confused? Let's look at an example:

English	bad	[bɛd]	pad	[pʰɛd]
Cantonese	爆	[paːu] 'explode'	跑	[pʰaːu] 'run'

The little superscript ʰ is the aspiration. Even though English 'pad' is aspirated, that is not the contrasting feature - which becomes obvious in Cantonese, where only the aspiration distinguishes the words for exploding and running.

And Gaelic works just like Cantonese in this respect. Gaelic b, p, d, t, g, c are all voiceless, both broad and slender. So which one is which? b, d, g are simply voiceless, p t c are voiceless and aspirated at the start of a word, so in a pair like gas vs cas, the only difference between the two will be a puff of air following c.

To add to the confusion, Gaelic also pre-aspirates non-initial p t c in a stressed syllable. This means that they are not followed by a puff of air but rather preceded by one. Because p t c are always aspirated at the beginning of a word both in English and in Gaelic, it tends not to be indicated in IPA transcriptions to save on ink and parchment, but we've written it here since aspiration and devoicing is the topic of this page. So, to sum up, pre-aspiration usually comes out as a [h] or [x] followed by [b] [d] [g]. Here is a summary of these sounds:

	beginning	middle	end (one syllable word)	end (more than one syllable)
b (broad)	bó [boː]	cabar [kʰabər]	gob [gob]	dìleab [dʲiːləb]
b (slender)	beò [bjɔː]	caibeal [kaibəL]	guib [guib]	dìleib [dʲiːləb]
p (broad)	pasgan [pʰasgan]	mapa [mahbə]	cop [kʰɔhb]	stiorap [ʃdʲirəb]
p (slender)	peur [pʰiar]	cipean [kʲihban]	cuip [kʰuiʰb]	MacPhilip [maxg'filɪb]
d (broad)	doras [dorəs]	adag [adag]	ad [ad]	mulad [muLəd]
d (slender)	deò [dʲɔː]	spaideil [sbadʲal]	cuid [kʰudʲ]	abaid [abɪdʲ]
t (broad)	tobar [tʰobar]	bàta [baːhtə]	cat [kʰaht]	Langabhat [Laŋgəvad]
t (slender)	tiugh [tʲu]	càite [kʰaːhdʲə]	cait [kʰɛçdʲ]	bunait [bunadʲ]
g (broad)	gob [gob]	baga [bagə]	rag [Rag]	Mórag [moːrag]
g (slender)	geur [gʲiər]	aige [ɛgʲə]	buig [bugʲ]	aiseig [aʃɪgʲ]
c (broad)	cù [kʰuː]	aca [axga]	mac [maxg]	currac [kuRəg]
c (slender)	ceò [kʲɔː]	aice [ɛçkʲə]	mic [miçgʲ]	tiodhlaic [tʲɤːLɪgʲ]

In case you wondering about the odd examples in the last column - Gaelic just doesn't have that many words that have p t c in unstressed syllables. In an unstressed syllable Gaelic pronounces the pairs p/b, c/g, d/t exactly the same way so the spelling has long since given up trying to show the difference.

That's it really. Except to point out what you've already spotted:

• before c, the preaspiration is very strong, more like [x] and [ç]
• before t, it's middling, [h] generally
• before p, it's weak, closer to [ʰ]
• after a long vowel, it's weak too, [ʰ] or just not there at all