Many native speakers pronounce the word Toronto as tərɑnoʊ (Torono), dropping the second “t” sound.
Other native speakers will pronounce the word as tərɑntoʊ, keeping the second “t” sound.
Notice that in both pronunciations, the first “o” is reduced to the schwa sound /ə/.
When the word Toronto is followed by another word, as in the phrase “Toronto subway system”, native speakers are more likely to pronounce Toronto as tərɑnoʊ. For example, most native speakers would say, tərɑnoʊ subway system,
although many people might pronounce the phrase as tərɑntoʊ subway system.
Which pronunciation of Toronto do you use?