如何用php Tag替换方形标签

I have two type of tags. need to replace "[" with "<". i tried with str_replace but its not working.

first Tag:

$x = '<break time="2000ms"/>'; 
$y = '[pause="1000ms"]';


echo str_replace(['[ pause =','[pause=','[ pause=','[pause ='],"<break time",trim($y));

second Tag:

[pitch = "x-low"][endpitch]

convert to

<prosody pitch="x-low"></prosody>

Thanks in advance.

........Updated.........

$text = 'I am [pitch = "high"]Rudratosh Shastri[endpitch]. what is your name ? how  are you? sorry [pause="3000"] i can not hear you ?[rate="-70.00%"] i still can\'t hear you[endrate] ? [rate="+50.00%"]why i can\'t hear you[endrate] ?';

echo $text = preg_replace("/\[pause.*\"(\w+)\".*\]/", '<break time="$1ms"/>', $text);

output: I am [pitch = "high"]Rudratosh Shastri[endpitch]. what is your name ? how are you? sorry <break time="3000ms"/> ?

Not getting output after break time tag.