CSS voice-rate

The CSS voice-rate property is used in speech media to specify the speaking rate in words per minute.

In other words, the voice-rate property defines how fast the synthesized voice speaks when reading out the content.

Syntax

Possible Values

normal

Specifies that the default rate should be used. What constitutes "default" depends on the speech synthesizer, the language, the dialect, and the personality of voice being used.

x-slow

Extra slow. In English, this is typically around 80 words per minute

slow

Slow. In English, this is typically around 120 words per minute

medium

Medium voice rate. In English, this is typically around 180 - 200 words per minute

fast

Fast. In English, this is typically around 300 words per minute

x-fast

Extra fast. In English, this is typically around 500 words per minute

percentage

Only non-negative percentage values are allowed. This represents a change relative to the given keyword value, or to the default value for the root element, or otherwise to the inherited speaking rate (which may itself be a combination of a keyword value and of a percentage, in which case percentages are combined multiplicatively).

In addition, all CSS properties also accept the following CSS-wide keyword values as the sole component of their property value:

initial

Represents the value specified as the property's initial value.

inherit

Represents the computed value of the property on the element's parent.

unset

This value acts as either inherit or initial, depending on whether the property is inherited or not. In other words, it sets all properties to their parent value if they are inheritable or to their initial value if not inheritable.

General Information

Example Code

Official Specifications

• CSS Speech Module (W3C Candidate Recommendation 20 March 2012)

Vendor Prefixes

For maximum browser compatibility many web developers add browser-specific properties by using extensions such as -webkit- for Safari, Google Chrome, and Opera (newer versions), -ms- for Internet Explorer, -moz- for Firefox, -o- for older versions of Opera etc. As with any CSS property, if a browser doesn't support a proprietary extension, it will simply ignore it.

This practice is not recommended by the W3C, however in many cases, the only way you can test a property is to include the CSS extension that is compatible with your browser.

The major browser manufacturers generally strive to adhere to the W3C specifications, and when they support a non-prefixed property, they typically remove the prefixed version. Also, W3C advises vendors to remove their prefixes for properties that reach Candidate Recommendation status.

Many developers use Autoprefixer, which is a postprocessor for CSS. Autoprefixer automatically adds vendor prefixes to your CSS so that you don't need to. It also removes old, unnecessary prefixes from your CSS.

You can also use Autoprefixer with preprocessors such as Less and Sass.