Depending on how the person says the following word:
Neerazhi (നീരാഴി) - a synonym for the word "sea"
You can determine how much Malayalam a person knows, how "native" he or she is from the way they pronounce this word.
The na, ra, and zha are different!
TIDBITS
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From Wikipedia,
Extinct Kannada letters
Kannada literary works employed letters ಱ (transliterated 'ṟ' or 'rh') and ೞ (transliterated 'ḻ', 'lh' or 'zh'), whose manner of articulation most plausibly could be akin to those in present-day Malayalam and Tamil. The letters dropped out of use in the twelfth and eighteenth centuries, respectively. Later Kannada works replaced 'rh' and 'lh' with ರ (ra) and ಳ (la) respectively.[70]
Another letter (or unclassified vyanjana (consonant)) that has become extinct is 'nh' or 'inn'. (Likewise, this has its equivalent in Malayalam and Tamil.) The usage of this consonant was observed until the 1980s in Kannada works from the mostly coastal areas of Karnataka (especially the Dakshina Kannada district). Now hardly any mainstream works use this consonant. This letter has been replaced by ನ್ (consonant n).[citation needed]