Using the HMM-based Singing Voice Synthesis System from the Nagoya Institute of Technology I implented a program to convert music sheets in midi file format into voices that sing the specified notes. Here you can find a sample cover of Lady Gaga - Shallow.
You can try it by yourself installing it with pip, the python packages manager. If you don’t have python and pip you can try it online with this colab notebook.
This project has been used by different people around the internet, here are a few examples: