From my understanding (I took two relevant undergrad courses, definitely not an expert) lossy compression can involve either losing certain frequencies (like th

From my understanding (I took two relevant undergrad courses, definitely not an expert) lossy compression can involve either losing certain frequencies (like those above/below human hearing), or losing the accuracy of the reproduction (like a certain frequency component of the sound could be the smallest bit louder/quieter or higher/lower than it was originally).