Is /z/ pronounced as [z] or [dz] or both?


I am not sure how these two sounds are used in Japanese. Which one is more
common, in terms of frequency? Under what cases is the other one used?




From _The Sounds of Japanese_ (Vance 2008), p.85:

> We'll transcribe [dz] phonemically as /z/ because there's no contrast
> between [dz] and the voiced lamino-alveolar fricative [z]. **Typically,
> though not consistently, [dz] occurs at the beginning of a word or in the
> middle of a word immediately following a syllable-final consonant (§5.1,
> §5.6), and [z] occurs in the middle of a word immediately following a
> vowel.** In short, [dz] and [z] are allophones of this /z/ phoneme. Most
> native speakers of Japanese are quite surprised to discover there's actually
> a phonetic difference to worry about, but you'll hear it if you listen
> carefully to pronunciations of _zu_ [dzɯ] 図 'diagram' and _chizu_ [cɕizɯ] 地図
> 'map'.

In the above, "a syllable-final consonant" means either `ん` /N/ or `っ` /Q/,
which Vance explains in sections §5.1 and §5.6 respectively. In the latter
section (p.108), he goes on to write:

> As we saw in §4.3, /z/ has both [z] and [dz] as careful-pronunciation
> allophones, but following /Q/, /z/ is always [dz].

Although note that voiced [geminates](http://en.wikipedia.org/wiki/Geminate)
like this appear almost exclusively in loanwords, and even there under certain
conditions are commonly devoiced--see e.g. [_A corpus-based study of geminate
devoicing in Japanese_ (Kawahara and Sano
2013)](http://user.keio.ac.jp/~kawahara/pdf/KawaharaSano2013.pdf) or their
other recent work for discussion.




From _The Sounds of Japanese_ (Vance 2008), p.85:

> We'll transcribe [dz] phonemically as /z/ because there's no contrast
> between [dz] and the voiced lamino-alveolar fricative [z]. **Typically,
> though not consistently, [dz] occurs at the beginning of a word or in the
> middle of a word immediately following a syllable-final consonant (§5.1,
> §5.6), and [z] occurs in the middle of a word immediately following a
> vowel.** In short, [dz] and [z] are allophones of this /z/ phoneme. Most
> native speakers of Japanese are quite surprised to discover there's actually
> a phonetic difference to worry about, but you'll hear it if you listen
> carefully to pronunciations of _zu_ [dzɯ] 図 'diagram' and _chizu_ [cɕizɯ] 地図
> 'map'.

In the above, "a syllable-final consonant" means either `ん` /N/ or `っ` /Q/,
which Vance explains in sections §5.1 and §5.6 respectively. In the latter
section (p.108), he goes on to write:

> As we saw in §4.3, /z/ has both [z] and [dz] as careful-pronunciation
> allophones, but following /Q/, /z/ is always [dz].

Although note that voiced [geminates](http://en.wikipedia.org/wiki/Geminate)
like this appear almost exclusively in loanwords, and even there under certain
conditions are commonly devoiced--see e.g. [_A corpus-based study of geminate
devoicing in Japanese_ (Kawahara and Sano
2013)](http://user.keio.ac.jp/~kawahara/pdf/KawaharaSano2013.pdf) or their
other recent work for discussion.

