Pronunciation question: the word पहला
Why is पहला pronounced /pɛːʱ.lɑː/? Specifically, there seems to be a ऐ sound enunciated after प instead of the implied vowel अ. Is this an exception or a rule I should know about? I've also noticed this in practice in the word पहलवान /pɛːʱl.ʋɑː.n/.
This is one of the most common exceptions to pronunciation you'll see in Hindi, when ह is placed in between two other consonants, both the consonant before ह as well as ह itself are followed by an ऐ sound instead of the usual अ sound. Some examples: बहन (sister) pronounced as "behen", महंगा (expensive) pronounced as "mehenga", कहना (to say) pronounced as "kehena." You'll get used to it the more words you hear like this, it's just one of those exceptions, perhaps it should be pronounced phonetically but it just isn't for some reason.
Let me tell you - Correct Hindi is when you pronounce it as it is written. The Devnagari script does not have silent sounds and exceptions like the Latin script.
Further, your question is a lot to do with accent and region than actual technical pronunciation.
In Uttar Pradesh, especially in a lot of rural areas, People normally say 'puh-ha-laa' but that is not the case in many of the other regions where it is pronunced as 'Peh-la'
Do not get bothered by this as it is unnecessary and will only add to confusion while learning the language.