Understanding AVSpeechSynthesizer and Voice Languages in iOS

AVSpeechSynthesizer is a powerful class in iOS that allows developers to synthesize speech from text. It provides an efficient way to generate natural-sounding audio for voice assistants, audiobooks, podcasts, or any other application that requires spoken content.

One of the key features of AVSpeechSynthesizer is its ability to support different languages and voices. In this article, we will explore how to use AVSpeechSynthesizer with various language settings, including the British voice for US iPhones.

Overview of AVSpeechSynthesizer

AVSpeechSynthesizer is a subclass of NSObject that conforms to the AVSpeechSynthesisVoiceDelegate protocol. It provides an interface for creating and managing speech utterances, which are instances of the AVSpeechUtterance class. These utterances can be used to synthesize text into spoken audio.

The synthesizer uses a combination of algorithms and machine learning models to generate natural-sounding speech. The quality and accuracy of the synthesized speech depend on various factors, including the voice model used, the language settings, and the device’s hardware capabilities.

Language Support in AVSpeechSynthesizer

AVSpeechSynthesizer supports a wide range of languages, including English, Spanish, French, German, Italian, Portuguese, Dutch, Russian, Chinese, Japanese, Korean, and many others. Each language has its own set of voice models, which are used to generate speech.

To use a specific language with AVSpeechSynthesizer, you need to create an instance of AVSpeechUtterance and set its voice property using the voiceWithLanguage: method. This method takes a string parameter that represents the language code, such as “en-gb” for British English or “en-au” for Australian English.

Voice Models and Language Codes

The voice models used by AVSpeechSynthesizer are stored in the device’s language data bundle. The language data bundle is a separate package that contains all the necessary files and data for each supported language, including text samples, audio recordings, and machine learning models.

Each voice model is associated with a specific language code, which can be used to identify the voice and its corresponding language. Here are some common language codes used in AVSpeechSynthesizer:

• en-gb: British English
• en-au: Australian English
• en-us: American English
• fr-fr: French (France)
• de-de: German (Germany)
• it-it: Italian (Italy)

Sample Code

To test the support for different languages, you can use the following code snippet:

#import <AVFoundation/AVFoundation.h>

int main() {
    AVSpeechSynthesizer *synthesizer = [[AVSpeechSynthesizer alloc] init];
    
    // Create an instance of AVSpeechUtterance
    AVSpeechUtterance *speechUtterance = [AVSpeechUtterance speechUtteranceWithString:@"This is something really special that a speech system could read out."];
    
    // Set the voice to British English
    speechUtterance.voice = [AVSpeechSynthesisVoice voiceWithLanguage:@"en-gb"];
    
    // Set the rate of the synthesizer
    speechUtterance.rate = 0.20;
    
    // Synthesize the speech
    [synthesizer speakUtterance:speechUtterance];
    
    return 0;
}

This code creates an instance of AVSpeechSynthesizer and sets its voice to British English using the voiceWithLanguage: method. The synthesizer then generates natural-sounding audio for the specified text.

Results

According to the developer’s experience, the results are as follows:

• Using en-gb produces a male voice with an English accent.
• Using en-au produces a female voice with Australian accent.
• Using en-us produces a female voice with no accent (i.e., American accent).

The same results were observed on both an iPad mini and a 5th generation iPod touch.

Conclusion

In conclusion, AVSpeechSynthesizer supports a wide range of languages, including English, Spanish, French, German, Italian, Portuguese, Dutch, Russian, Chinese, Japanese, Korean, and many others. By using the voiceWithLanguage: method to set the voice, developers can choose from various language options, including British English.

The sample code provided demonstrates how to use AVSpeechSynthesizer with different languages, including British English. The results show that the synthesizer generates natural-sounding audio for each language setting.

By utilizing AVSpeechSynthesizer and its language features, developers can create voice assistants, audiobooks, podcasts, or other applications that require spoken content in various languages.

Last modified on 2024-01-03