CSS (Cascading Style Sheets) is well known for controlling how elements appear visually on a website. However, CSS isn’t limited to only visual presentations. It also has a part called the Aural Style Sheets or Aural CSS, which is designed to control how content is presented to users using speech-based or screen reader devices.
The CSS Aural Reference is a set of properties intended to define how content should be read aloud. This is especially useful for visually impaired users who rely on assistive technologies such as screen readers, talking browsers, or other speech synthesizers.
Introduction to Aural CSS
Aural CSS was introduced as part of the CSS2 specification. While it is not widely implemented today due to newer accessibility standards like ARIA and semantic HTML, it was originally designed to provide fine-grained control over how content sounds when read aloud. It aimed to create a better auditory experience for users relying on audio-based output, similar to how CSS controls layout for visual users.
This means Aural CSS can affect things like:
- Volume and pitch
- Speaking rate
- Voice characteristics
- Pauses and emphasis
- Background sounds
Why Is Aural CSS Important?
The goal of Aural CSS is to support accessible web design. Websites should be inclusive, and this includes making sure content is accessible to users with visual impairments or learning disabilities. Aural CSS:
- Provides better control over how content is read by screen readers.
- Helps web developers craft a more natural and engaging voice experience.
- Enables websites to offer rich multimedia experiences, even through sound alone.
Although modern accessibility practices mostly rely on ARIA roles and semantic HTML, understanding the Aural CSS reference helps us appreciate the history and development of audio accessibility in web design.
Core Properties in CSS Aural Reference
Here are the key properties included in the Aural CSS reference:
1. volume
This property controls how loud the spoken content is. It can range from silent to loud, and accepts values like:
silentx-soft,soft,medium,loud,x-loud- Numeric values (e.g.,
50%)
Example:
p {
volume: loud;
}
2. speak
Controls whether the content should be spoken or not. This is useful for hiding decorative content from screen readers.
Values:
normal: Speak the content normally.none: Do not speak the content.spell-out: Spell the words letter-by-letter.
Example:
abbr {
speak: spell-out;
}
3. pause-before / pause-after
These properties add a pause before or after an element is spoken. Useful for structuring audio output.
Values:
none- Time-based values like
200msor1s
Example:
h1 {
pause-before: 500ms;
pause-after: 500ms;
}
4. cue-before / cue-after
These allow the addition of sound files before or after an element is spoken, like beeps or chimes.
Example:
blockquote {
cue-before: url("chime.wav");
}
5. play-during
Plays background audio while the content is being spoken.
Example:
body {
play-during: url("background.mp3");
}
6. speak-punctuation
Controls whether punctuation is pronounced or ignored.
Values:
code: Read punctuation as words.none: Ignore punctuation.
7. speak-numeral
Controls how numbers are spoken.
Values:
digits: Read each digit separately (e.g., “1 2 3”).continuous: Read the full number (e.g., “one hundred twenty-three”).
8. pitch, pitch-range, stress, richness
These control the characteristics of the voice:
- Pitch – How high or low the voice sounds.
- Pitch-range – Variability in pitch.
- Stress – Emphasis placed on syllables.
- Richness – Fullness of the voice tone.
Example:
strong {
pitch: high;
stress: 80;
}
Real-World Use and Support
While Aural CSS was a forward-thinking concept, it is not well supported in modern browsers. Most screen readers and accessibility tools rely on semantic HTML, ARIA roles, and operating system settings for voice behavior, rather than CSS.
However, Aural CSS laid the foundation for thinking about audio as a first-class mode of interaction on the web. Its ideas influenced modern accessibility standards.
Modern Alternatives
In practice today, developers are encouraged to use:
- ARIA (Accessible Rich Internet Applications) attributes like
aria-label,aria-hidden,aria-live, etc. - Screen-reader friendly HTML: such as
<nav>,<header>,<main>,<button>, etc. - JavaScript and Web Speech API for speech synthesis and recognition.
These modern tools offer better cross-browser and assistive technology support.
Summary
CSS Aural Reference is an older, specialized feature of CSS that was designed to control how content sounds when read aloud. It includes properties like volume, speak, pause, pitch, and more to create a structured, pleasant auditory experience.
Although it’s not widely used today, it provides a valuable historical perspective on the evolution of web accessibility. Today, developers use a combination of ARIA, semantic HTML, and the Web Speech API to create rich, inclusive, and accessible user experiences.
Conclusion
Understanding the CSS Aural Reference helps web developers appreciate the broader vision of accessibility beyond visuals. While most modern websites don’t use Aural CSS directly, its concepts still influence how we design for all users—especially those who interact with websites through sound rather than sight.
As technology continues to evolve, the future of audio-first web design may bring back some of these ideas in new, more powerful forms. Until then, the key is to build with empathy, ensuring your content reaches everyone, no matter how they access it.