A simultaneous increase in both the demand for headphones and the supply of headphones would imply that A simultaneous increase in both the demand for headphones and the supply of headphones would imply that the value of headphones to consumers has increased and the cost of producing headphones has decreased. the value of headphones to consumers has decreased and the cost of producing headphones has increased. both the value of headphones to consumers and the cost of producing headphones has increased. both the value of headphones to consumers and the cost of producing headphones has decreased