Apple's Siri hasn't made much progress in this area, while Amazon's voice assistant Alexa has been able to do so, because Siri can't distinguish between noisy environment and quiet environment. If Apple continues to work on the patent, Siri will soon speak in a different way. This means that if the user has to raise his voice so that Siri can hear him, the voice assistant will also respond at a higher volume.
Apple has been improving strong Siri. For example, the voice assistant knows 20 times more than it did three years ago. On wwdc19, Apple has added a more humanized voice to the virtual assistant to make the sentences clearer. With IOS 14.5, Siri has also acquired two new English sounds.
In addition, Apple has established a database of 28000 audio clips provided by stuttering users, which contains audio content recorded or specially made by stuttering users. This is conducive to Apple's better study of how Siri should deal with these content. An apple spokesman said the content in the library will be used to train Siri and improve the ability of speech recognition systems to understand users with language barriers.