CSS voice-volume

The CSS voice-volume property is used in speech media for controlling the amplitude of the audio waveform generated by the speech synthesiser.

The voice-volume property can also be used for adjusting the relative volume level of audio cues within the aural box model of the selected element.

You can use the voice-volume property to adjust the volume level of spoken content when the content is being read out by a device such as a screen reader.

Syntax

Possible Values

decibel

A number followed by dB (decibel unit identifier).

This represents a change (positive or negative) relative to the given keyword value, or to the default value for the root element, or otherwise to the inherited volume level (which may itself be a combination of a keyword value and of a decibel offset, in which case the decibel values are combined additively).

silent

No sound at all. The content is read silently. Therefore, the selected element takes up the same time as if it is being read out loud. To prevent this, set the speak property to none.

x-soft, soft, medium, loud, x-loud

These keywords are mapped to values determined by the user agent that meet the listener's requirements with regards to perceived loudness. Generally, the user can customize these base values via their preferences (or similar interface) in a way that's suitable to their auditory environment.

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 Level 1

Browser Support

Browser support for CSS properties can vary, particularly for newer or experimental features. Check current browser compatibility before using a property in production, especially when supporting older browsers.

Initial Value

CSS properties have an initial value that applies when the property has not been explicitly set. The initial value is different from the value inherited from a parent element and may vary between properties.

Inheritance

Some CSS properties inherit their computed value from their parent element by default, while others do not. The inherit, initial, unset, and revert keywords can also be used to control how a property gets its value.

Vendor Prefixes

Most modern CSS properties use the standard, unprefixed syntax. Vendor-prefixed properties such as -webkit- are mainly relevant to older browser versions or specific features and should only be used when required by your browser support targets.