Modern browsers APIs are making this kind of task super easy to achieve!

Ok, I could have exaggerated a bit... But let's go straight to the point and then add some details.

In order to make your browser talk, just write this line of code:

speechSynthesis.speak(new SpeechSynthesisUtterance('Hello!'));

How simple is that?! Many years ago it would have been unthinkable to do such a thing, but nowadays modern browsers give you access to the new Web Speech API.

Web Speech Api features

1. Speech Synthesis API (aka text-to-speech): is the ability of a machine to translate a text into spoken speech automatically, and it's the API I used to make the browser talk.
2. Speech Recognition API (aka speech-to-text): is the ability of a machine to identify words spoken aloud and convert them into readable text.

Speech Synthesis

In order to make our browser speak, we use the SpeechSynthesisUtterance interface.

Firstly, we have to create a new SpeechSynthesisUtterance instance that accepts only one parameter (the sentence):

const utterance = new SpeechSynthesisUtterance('Hello!')

There are a lot of SpeechSynthesisUtterance properties we can manage:

• language (lang) → A string representing a BCP 47 language tag.
• speed (rate) → default=1, min=0.1, max=10
• pitch → default=1, min=0, max=2
• volume → default=1, min=0(mute), max=1

If you want to explore other features of SpeechSynthesisUtterance you can browse the MDN Doc.

Let's discover how we can "tune" the browser's voice:

utterance.lang = 'en-US' // A string representing a BCP 47 language tag
utterance.rate = 0.5; // Represent the speed
utterance.pitch = 2;
utterance.volume = 0.5; // mute=0, max=1

And now, let the browser speak!

speechSynthesis.speak(utterance);

Events

We are also able to listen to a lot of events too:

• onstart
• onend
• onpause
• onresume
• onerror
• onmark (See SSML mark tag)

Print out to the console once an event occurs:

utterance.onstart = (event) => console.log('Speech has started', event);

utterance.onend = (event) => console.log('Speech has ended', event);

Speech Syntesis is well-supported on major browsers, on the contrary Speech Recognition is partially supported.

If you want to check whether your browser supports this feature, you can
browse caniuse.com to have more details.

NB: There are still some problems with "onpause" and "onresume", so use it carefully:

• https://github.com/WICG/speech-api/issues/82
• https://stackoverflow.com/questions/34877206/speechsynthesis-onpause-onresume-does-not-fire
• https://bugs.chromium.org/p/chromium/issues/detail?id=425553
• https://github.com/WICG/speech-api/issues/82

Demo

Theory is useless without practice, thus I created a stackblitz project with a bunch of SpeechSynthesisUtterance features you can play with.