This is the full table of supported voices and languages for Plivo in JSON format (useful for Node.js developers).

plivo-locales.json

[
  {
    "language":"Arabic",
    "value":"arabic",
    "women":false,
    "man":true
  },
  {
    "language":"Czech",
    "value":"cs-CZ",
    "women":true,
    "man":false
  },
  {
    "language":"Danish",
    "value":"da-DK",
    "women":true,
    "man":false
  },
  {
    "language":"German",
    "value":"de-DE",
    "women":true,
    "man":true
  },
  {
    "language":"Greek",
    "value":"el-GR",
    "women":true,
    "man":false
  },
  {
    "language":"English - Australian",
    "value":"en-AU",
    "women":true,
    "man":false
  },
  {
    "language":"English - Canadian",
    "value":"en-CA",
    "women":true,
    "man":false
  },
  {
    "language":"English - British",
    "value":"en-GB",
    "women":true,
    "man":true
  },
  {
    "language":"English - USA",
    "value":"en-US",
    "women":true,
    "man":true
  },
  {
    "language":"Spanish",
    "value":"es-ES",
    "women":true,
    "man":true
  },
  {
    "language":"Spanish - USA",
    "value":"es-US",
    "women":true,
    "man":true
  },
  {
    "language":"Finnish",
    "value":"fi-FI",
    "women":true,
    "man":false
  },
  {
    "language":"French - Canadian",
    "value":"fr-CA",
    "women":true,
    "man":true
  },
  {
    "language":"French",
    "value":"fr-FR",
    "women":true,
    "man":true
  },
  {
    "language":"Hungarian",
    "value":"hu-HU",
    "women":true,
    "man":false
  },
  {
    "language":"Italian",
    "value":"it-IT",
    "women":true,
    "man":true
  },
  {
    "language":"Japanese",
    "value":"ja-JP",
    "women":true,
    "man":true
  },
  {
    "language":"Dutch",
    "value":"nl-NL",
    "women":true,
    "man":true
  },
  {
    "language":"Polish",
    "value":"pl-PL",
    "women":true,
    "man":false
  },
  {
    "language":"Portuguese - Brazilian",
    "value":"pt-BR",
    "women":true,
    "man":false
  },
  {
    "language":"Portuguese",
    "value":"pt-PT",
    "women":true,
    "man":true
  },
  {
    "language":"Russian",
    "value":"ru-RU",
    "women":true,
    "man":true
  },
  {
    "language":"Swedish",
    "value":"sv-SE",
    "women":true,
    "man":false
  },
  {
    "language":"Chinese",
    "value":"zh-CN",
    "women":true,
    "man":true
  }
]

Here is the code used to generate this was used in Chrome Dev Tools at: http://plivo.com/docs/xml/speak/#supportedlang

var rows = $('#supportedlang').find('table').find('tbody').find('tr')
var obj = []
for(var i=0; i<rows.length; i++) {
  var row = $(rows[i]).find('td')
  console.log('row', row[0].innerText)
  obj.push({
    language: row[0].innerText,
    value: row[1].innerText,
    women: row[2].innerText === 'yes',
    man: row[3].innerText === 'yes'
  })
}
console.log(JSON.stringify(obj))