The concept of vision, particularly of non-luminous objects, has been the subject of recent research, but comparatively little has been done in the area of sound and hearing, despite the fact that, though there are clear distinctions, the two have much in common. The present work uses a combined free response questionnaire and interview procedure to probe pupils' ideas regarding how they believe they see both luminous and non-luminous objects, and how they think they hear a source of sound. From the large sample of pupils studied, the prevalence of the ideas in different age groups is compared, and progression can be seen. Some suggestions are offered for teaching strategies which might aid this progression.