Text-to-Speech Powered by Amazon Polly

To control speech parameters, it is necessary for the text in the Text-to-Speech section to be between the opening <speak> and closing </speak> tags. 

Example: 
<speak>Hello and thank you for calling our Support line.</speak>

With that in mind, it is now possible to use different control mechanisms to adapt the speech to specific needs.

To emphasize words, the <emphasis> tag can be used. Emphasizing words changes the speaking rate and volume. To do that:
1. Place the opening tag <emphasis level=”value”> and the closing </emphasis> tag on the part of the speech that you want to change the emphasis. The supported values are the following:
 - “Strong”: Increases the volume and slows the speaking rate so that the speech is louder and slower.
 - “Moderate”: Increases the volume and slows the speaking rate, but less than strong. Moderate is the default.
 - “Reduced”: Decreases the volume and speeds up the speaking rate. Speech is softer and faster.
Example:
<speak>Hello and thank you for calling our <emphasis level=”strong”>Support line</emphasis>. We wish you a great day</speak>

To control the volume, speaking rate, and pitch of the voice, the <prosody> tag can be used. To do that:

1. Place the opening tag <prosody volume=”value”> and the closing </prosody> tag on the part of the speech that you wish to control the volume. The supported values are the following:
 - “default”: Resets volume to the default level for the current voice.
 - “silent”, “x-soft”, “soft”, “medium”, “loud”, “x-loud”: Sets the volume to a predefined value for the current voice.
 - “+ndB”, “-ndB”: Changes volume relative to the current level. A value of +0dB means no change, +6dB means approximately twice the current volume, and -6dB means approximately half the current volume. 
Example:
<speak>Hello and thank you for calling our <prosody volume=”loud”>Support line</prosody>. We wish you a great day</speak>

1. Place the opening tag <prosody rate=”value”> and the closing </prosody> tag on the part of the speech that you wish to control the speaking rate. The supported values are the following:
  - “x-slow”, “slow”, “medium”, “fast”, “x-fast”: Sets the speech rate to a predefined value for the selected voice.
  - “n%”: A positive percentage change in the speaking rate. For example, a value of 100% means no change in speaking rate, a value of 200% means a speaking rate twice the default rate, and a value of 50% means a speaking rate of half the default rate. This value has a range of 20-200%. 

Example 1:
<speak>Hello and thank you for calling our <prosody rate=”fast”>Support line</prosody>. We wish you a great day</speak>

Example 2:
<speak>Hello and thank you for calling our <prosody rate=”60%”>Support line</prosody>. We wish you a great day</speak>

1. Place the opening tag <prosody pitch=”value”> and the closing </prosody> tag on the part of the speech that you wish to control the pitch of the voice. The supported values are the following:
 - “x-low”, “low”, “medium”, “high”, “x-high”: Sets the pitch to a predefined value for the current voice.
 - “+n%” or “-n%”: Adjusts pitch by a relative percentage. For example, a value of +0% means no baseline pitch change, +5% gives a little higher baseline pitch, and -5% results in a little lower baseline pitch.
Example:
<speak>Hello and thank you for calling our <prosody pitch=”x-low”>Support line</prosody>. We wish you a great day</speak>

To control how special types of words are spoken, the <say-as interpret-as> tag can be used. To do that:
1. Place the opening tag <say-as interpret-as=”value”> and the closing </say-as> tag on the part of the speech that you wish to adopt. The supported values are the following:
  - “characters” or “spell-out”: Spells out each letter of the text, as in a-b-c.

- “cardinal” or “number”: Interprets the numerical text as a cardinal number, as in 1,234.
  - “ordinal”: Interprets the numerical text as an ordinal number, as in 1,234th.
  - “digits”: Spells out each digit individually, as in 1-2-3-4.
  - “fraction”: Interprets the numerical text as a fraction. This works for both common fractions, such as 3/20, and mixed fractions, such as 2 ½. If you would like to insert 4 ½ to be read as “four and a half”, then you need to define the text as “4+½” (example: <say-as interpret-as="fraction">4+1/2</say-as> will read as “three and a half”).
  - “unit”: Interprets a numerical text as a measurement. The value should be either a number or a fraction followed by a unit with no space in between, as in 1/2inch, or by just a unit, as in 1meter.
  - “date”: Interprets the text as a date. The format of the date must be specified with the format attribute. See below for more information.
   - When “interpret-as” is set to “date”, you also need to indicate the format of the date. This uses the following syntax: <say-as interpret-as="date" format="format">[date]</say-as>
   The following formats can be used: 
     - “mdy”: Month-day-year.
     - “dmy”: Day-month-year.
     - “ymd”: Year-month-day.
     - “md”: Month-day.
     - “dm”: Day-month.
     - “ym”: Year-month.
     - “my”: Month-year.
     - “d”: Day.
     - “m”: Month.
     - “y”: Year.
     - “yyyymmdd”: Year-month-day. If you use this format, you can make Amazon Polly skip parts of the date using question marks.

Example using the tag:
<speak>Hello and thank you for calling our support line. We will be closed on <say-as interpret-as=”date” format=”md”>25/12/2021</say-as>. Thank you for understanding.</speak>
“time”: Interprets the numerical text as duration, in minutes and seconds, as in 1'21".

Example for the <say-as interpret-as=”value”> tag:
<speak>Hello and thank you for calling our Support line. Here is a promo code for you <say-as interpret-as=”characters”>U74HDDKOM</say-as>. We wish you a great day</speak>

To make adjustments to how some words are pronounced, the <phoneme> tag can be used. To use the tag, it will be mandatory to also add two attributes that will indicate how the pronunciation should occur. Those two attributes are: 
- Alphabet (and respective supported values):
   - “ipa”:  Indicates that the International Phonetic Alphabet (IPA) will be used.
   - “x-sampa”:  Indicates that the Extended Speech Assessment Methods Phonetic Alphabet (X-SAMPA) will be used.
-ph:
   - Specifies the phonetic symbols for pronunciation. For more information, consult this page.

See below two examples (one using ipa, the other one using x-sampa) using the phoneme tag:

Example (using “ipa”):
<speak> You say, <phoneme alphabet="ipa" ph="pɪˈkɑːn">pecan</phoneme>. I say, <phoneme alphabet="ipa" ph="ˈpi.kæn">pecan</phoneme>.</speak>

Example (using “x-sampa”):
<speak> You say, <phoneme alphabet='x-sampa' ph='pI"kA:n'>pecan</phoneme>. I say, <phoneme alphabet='x-sampa' ph='"pi.k{n'>pecan</phoneme>. 
</speak>

Note: Please bear in mind the difference between using “ipa” and “x-sampa”. When using “ipa”, double quotation marks (“) should be used for the values that the attributes use. When using “x-sampa”, one should use single quotation marks (‘). This is because the double quotation mark (“) in “x-sampa” is used to define the primary stress of a word.