If you're talking about "high" in terms of height or elevation:
* Alto is the most common word.
If you're talking about "high" in terms of volume or intensity:
* Alto can still be used, but fuerte (strong, loud) is often a more appropriate choice.
If you're talking about "high" as a musical register:
* Alto is used directly, just as in English.
Examples:
* "El edificio es muy alto." (The building is very high.)
* "La música está demasiado fuerte." (The music is too loud.)
* "La cantante es alto." (The singer is an alto.)
Remember that the meaning of "alto" can change depending on the context, so pay attention to the surrounding words to understand its intended meaning.