I understand that you want to know if there is a way to specify a shorter break when using the <break> ssml tag.

If you do need to adjust the length of the duration you can use the strength attribute values:

none: 		No pause. Use none to remove a normally occurring pause, such as after a period.
x-weak: 	Has the same strength as none, no pause.
weak: 		Sets a pause of the same duration as the pause after a comma.
medium: 	Has the same strength as weak.
strong: 	Sets a pause of the same duration as the pause after a sentence.
x-strong:	Sets a pause of the same duration as the pause after a paragraph.

If you find the need to fine-tune the duration of the pause you can use the time attribute values, an example can be found here [1]:

[number]s:	The duration of the pause, in seconds. The maximum duration is 10s.
[number]ms: The duration of the pause, in milliseconds. The maximum duration is 10000ms

Reference :

[1] Supported SSML Tags - Adding a Pause - https://docs.aws.amazon.com/polly/latest/dg/supportedtags.html#break-tag

Hi Wael, thanks for you reply.

I understand what you mean and now it's clear to me why it doesn't work. I want to insert a small pause in the middle of the sentence. This should be shorter than a ",".

But it follows from your answer that a pause shorter than 250ms, which presumably corresponds roughly to the comma, does not work. I find this quite irritating in your description and in principle your explanation would be desirable as a supplement to your description.

If there is a possibility, I would be grateful for a hint. I would like to spell out contents. The pauses caused by a simple blank are sometimes too short and the pauses caused by my break time are then too long ;)

PS: Unfortunately I cannot use the SSML tags "Say As characters" for neural voices.