The correct order of steps in the process of hearing is sound wave -> eardrum vibration -> pressure wave in fluid, converting sound into a signal for the brain to understand.
The steps involved in transforming a sound into a signal that can be understood by the brain are as follows: Initially, sound waves travel up the ear canal and force the eardrum to vibrate. Subsequently, these vibrations are transmitted through the middle ear bones (malleus, incus, and stapes) and are then amplified.
The amplified vibrations are picked up by the oval window, resulting in pressure waves in fluid within the cochlea of the inner ear. Finally, this mechanical energy is transduced into electrical signals (nerve impulses) by the sensory cells in the cochlea, which are then interpreted by the brain as sound.
Therefore, the steps go in the following order: sound wave -> eardrum vibration -> pressure wave in fluid, which corresponds to option 1.