Weight and balance of a new telephone handset

Several identical prototype shells of a new telephone handset design were weighed in different ways to produce five different overall weights, ranging from 130 to 340 g, and three different balance conditions: transmitter-heavy, receiver-heavy, and balanced. Fifty-two subjects drawn from working people of both sexes and a range of ages participated in pair-comparison tests in which each subject gave a preference judgment for one handset over another for all possible pairs of handsets. They also rated each handset as acceptable or unacceptable. The best overall handset weighed 176 g with the weight equally distributed between transmitter and receiver. The lightest handset (130 g, balanced) was actually preferred by a majority of people over the balanced 176-gram set but twice as many people rated it unacceptable (31% vs 14%). All handsets weighing 176 g or less and the balanced handset weighing 224 g were rated as acceptable by at least two-thirds of the subjects. It is recommended that designs aim at a balanced handset weighing approximately 176 g. It would not be worthwhile to add weight to an unbalanced 176-gram set to bring it into balance.