Which component of the auditory system is the first to respond to sound stimuli?

The cochlea is the first component of the auditory system to respond to sound stimuli. Located within the inner ear, it plays a crucial role in the transduction of sound waves into neural signals. When sound enters the ear, it travels through the auditory canal and vibrates the eardrum, which in turn moves the ossicles (small bones within the middle ear). These vibrations are then transmitted to the fluid-filled cochlea.

Inside the cochlea, sound waves create waves in the fluid, causing the basilar membrane to vibrate. This vibration stimulates hair cells located on the organ of Corti, leading to the conversion of mechanical energy from sound waves into electrical signals. These electrical signals are then sent via the auditory nerve to higher brain centers for further processing.

In contrast, other components listed, such as the auditory cortex and the superior olive, are part of pathways that process sound information after it has been transduced by the cochlea. The cochlear nucleus, while involved in initial signal processing, relies on the cochlea's response to sound as its input. Therefore, the cochlea's role as the primary structure that first responds to sound stimuli makes it the correct choice for this question.