Do American people pronounce "mutter" like "mudder"?

Question

I heard "muttering" when I was practicing my listening.

I couldn't figure it out even I knew the meaning in the sentence. It sounded like "muddering". I searched "muder" in search engine, it gave me "murder". Finally, I gave it up, then watched the answer, it was a "muttering".

When I hear a word which I don't know, How do I find it out?

Answer 1

This is called flapping, and yes it does make both "mutter" and "mudder" sound exactly the same (both are /ˈmədər/). Flapping is done in American English and some other dialects of English.

In order to figure out what word you're hearing, context is vital, as is knowing a couple of likely candidate spellings:

• The search engine, in some cases, will know what you're trying to type if you search with context. For example, Google suggests the right spelling if I search for "muddering under your breath" or even "muering under your breath".
• In this case, you found one word it could be ("mudder", which is a very uncommon word), but you didn't find "mutter" because you didn't spell it with two t's (a single t is not right because it would be pronounced differently). It might be worth finding a dictionary that supports advanced search (I like this site, which uses regex syntax). A dictionary will help you know if the word fits or not in the sentence.
• Lastly, familiarity with the language always helps. The more you hear and read English, the more words you'll know.

You may also find this answer of mine helpful, since I explain more about flapping in general there.