Another word in spanish for no siempre that starts with a (a)

 A veces

Explanation: You can use (A veces) instead of (no siempre).

It is referring that sometimes you perform an activity.

for example

A veces voy al parque.

No siempre voy al parque.

In english (A veces) will be translated as sometimes.

i have to listen to the audio to be able to answer your question.