text: if you put two glasses on a glass table & run a finger round the rim of one of the glasses, will all resonate? if so, does this involve the same principle as sticking a female opera singer in a room full of glasses on shelves and asking her to sing in as high and loud a pitch as she can? things will only resonate at a particular frequency if they are all of the same density and tension (ie: it's unlikely that the glass table top will resonate with the wine glass as the glass table top is most certainly denser and is under load).