Between 1630 CE and 1707 CE, the Parisian goldsmiths' confraternity donated a series of over 70 large paintings to Notre-Dame as a show of religious devotion. Since the confraternity would present a new painting every year in a ceremony dedicated to Mary on the first of May, the donated paintings are collectively called "the Mays." To paint one of the Mays was a great honor, and the resulting paintings were of monumental scale (with an average area of 12.9 m 2 per painting), typically displayed just below the triforium level of Notre-Dame. Contemporaneous depictions of the cathedral's interior frequently show the Mays hanging along the cathedral's central aisle. Interestingly, in these engravings and paintings of Notre-Dame, there is little consistency in how the paintings are displayed. In some, the paintings hang parallel to the walls, while in others, they are angled downward. Additionally, the mounting height of the paintings changes across illustrations. Treating the Mays as semi-free-hanging acoustic reflectors, the current work assesses the acoustic effect of the materials of the paintings and the different mounting conditions from their installation in the cathedral through the beginning of the French Revolution.