CSS voice-range

The CSS voice-range property is used in speech media to specify the pitch range of the speaking voice.

More specifically, the voice-range property specifies the variability in the "baseline" pitch. In other words, how much the fundamental frequency may deviate from the average pitch of the speech output.

This setting can affect whether or not the voice has a monotone sound to it or a more animated tone. A monotone voice would indicate a lower voice range, whereas a more animated voice would have a higher voice range.

Syntax

Possible Values

frequency

This value represents the variation to the pitch in terms of frequency. It must be a valid frequency, which is a number immediately followed by a frequency unit identifier (i.e. Hz or kHz).

If the absolute keyword is present, this is an absolute frequency (it's not an increment or decrement).

absolute

This is an optional keyword that indicates that the specified frequency represents an absolute value (i.e. it's not an increment or decrement). If a negative frequency is specified, the computed frequency is zero.

semitones

Specifies a relative change (decrement or increment) to the inherited value. This is specified as a number followed immediately (no space) by st (semitones unit identifier).

x-low, low, medium, high, x-high

A sequence of monotonically non-decreasing pitch levels that are implementation and voice specific.

percentage

Positive and negative percentage values are allowed, to represent an increment or decrement (respectively) relative to the inherited value.

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.