CTS Guide: Sound, pp 190-191- Section IV Research Summaries
Production of Sound
A study of fifth graders’ ideas about how sound is produced and travels revealed several inaccurate ideas, including (1) sound is an “object” that moves from place to place, (2) sound bounces off of things to get to a person so he or she can hear it, and (3) sound moves through solids but not through air. The study also revealed that students could use the term vibration when describing sound but could not correctly identify the source of the vibrations or how the vibrations are related to sound. The researchers also conducted a study of two approaches to teaching sound, one more text-based and teacher directed and the other using a learning cycle constructivist approach. The study revealed that the students who were taught using the learning cycle approach were more enthusiastic and eager to participate in the sound activities. They made more observations, frequently asked relevant questions, and engaged in meaningful science talk. Evidence showed they could relate their changing ideas about sound to their classroom experiences as well as experiences outside the classroom. They were also more comfortable developing their own definitions and their own ideas about sound and better at retaining content from previous lessons (Barman, Barman, and Miller 1996).
Children's explanations of how sound is produced can be sorted into three groups that involve (1) physical properties of sound-producing materials, such as thickness, hardness, and elasticity, (2) the size of the force needed to produce the sound, and (3) vibrations. Reference to movement and vibration increases with age. Studies suggest that children may be confused about the speed or size of vibration: Bigger vibrations were thought to be slower than small vibrations and, consequently, difficulties arose in discussing pitch and volume. Failure to recognize the role of vibration in sound may be linked to the failure to recognize the involvement of air as a medium in which vibrations are transferred. The role of the ear does not appear to be problematic and may serve as a useful context to develop the idea of vibrations in air. (Driver et al. 1994).
Researchers found that some students think sound can be produced without any material objects (Hapkiewicz and Hapkiewicz 1993).
A study by Asoko, Leach, and Scott (1991) used different contexts to have students explain how sound is produced. They used examples such as a guitar string, a horn, cymbals, and two stones clashed together. The results of their study suggest that students do not have a generalized theory of sound being produced by vibration that can be transferred across different contexts. The researchers suggest that teachers should plan to give children experience of sound production in less obvious contexts as well as in contexts where the vibrations are clearer. It may be useful to allow the children to experiment with applying vibration ideas developed in obvious contexts to less obvious contexts with a view to developing a generalized theory.
In a study by Watt and Russell (1990), children suggest that sound is produced because an object is made of plastic or rubber or because it is thick, thin, taut, or hard. Mechanisms for sound production offered by children were dependent on what the sound-producing object was; their descriptions of how sound is produced from a rubber band were very different from the explanations proposed for a drum.