Brahma: in chanting

[Krishna Kalale]

I thought that sanskrit is phonetic - ie. you speak as you write unlike
english ( which has silent letters and difference in pronunciation
depending on the words letters are used).

For example why is Brahma written in sanskrit like brah-ma  rather than
bram-ha.  it is usually pronounced as bram-ha even in vedic chants.  This
makes the language less phonetic.
for example this is the case in most gita verses : bramharparnam bramha
havih bramhagnau brahmhana hutam....

Krishna Kalale