For the technique, the force with which the transducer is coupled to the medium affects the quality of the coupling at the transducer-fruit boundary. Increasing or decreasing the transducer coupling force will cause the second term of Eq. (3) to decrease or increase respectively. However, assuming all other parameters remain constant, the first term of Eq. (3), which represents the acoustic properties, will remain largely unchanged irrespective of the coupling force that is applied. Therefore, if the coupling force is unchanged between measurements, it is expected that the measurements from any number of samples will remain constant relative to one another, allowing the acoustic properties of the samples to be directly compared.