Professor Grimson is a member of my doctoral committee, so I thought it would be a good idea to make myself familiar with some of his research in vision, even though it may not apply directly to my own research in hearing. Indeed, the concentration in this book is on geometrical constraints for visual object recognition (as is fairly obvious from the title). It is not clear whether similar constraints are useful in hearing, or whether his approach, which is not based on modeling human perception, is directly relevant to my own work. Nonetheless, the presentation is rigorous and the results impressive.