Simpler amplitude_to_DB (#367)

* Simpler amplitude_to_DB

* flake8

Author: jaeyeun97

torchaudio/functional.py

@@ -293,10 +293,7 @@ def amplitude_to_DB(x, multiplier, amin, db_multiplier, top_db=None):
     x_db -= multiplier * db_multiplier
 
     if top_db is not None:
-        new_x_db_max = torch.tensor(
-            float(x_db.max()) - top_db, dtype=x_db.dtype, device=x_db.device
-        )
-        x_db = torch.max(x_db, new_x_db_max)
+        x_db = x_db.clamp(min=x_db.max().item() - top_db)
 
     return x_db