The new AwesomeTTS addin for Anki 2.1 produced surprisingly good quality speech when used with the Microsoft Azure ‘Nanami’ Female Neural voice.
You can clearly hear the intonation and it seems to pick up the correct reading depending on the context. Single words sound clipped, which is probably to be expected from the way the neural network has been trained on continuous speech and single words have to be ‘cut-out’ from that.
It only occasionally struggled with 市場, always pronoucing as しじょう (stock/foreign) market, when I would have sometimes expected いちば (shipping) marketplace, showing that it had been trained mainly on news sources.
You don’t need to become a patron of AwesomeTTS but you will need to register for a free Micosoft Azure cloud account at https://azure.microsoft.com. Eventually, Microsoft’s registration process will ask you for a credit card number. You will only get charged if you go over the 500,000 free characters per month. Also, you can set alerts if you get charged.
On Azure, you will need to generate an API key which you paste into the setting for the AwesomeTTS addin. You can generate audio files and fields for up to twenty Anki cards in one go. Then you have to pause a few seconds before making another such request.