International Licensing Examination (ILE) Practice Test

Which type of cells in the cochlea are primarily responsible for amplifying sound vibrations?

1. Inner hair cells

2. Outer hair cells

3. Supporting cells

4. Auditory neurons

The correct answer is: Outer hair cells

The outer hair cells in the cochlea play a crucial role in amplifying sound vibrations. These cells contain special proteins that allow them to change their shape in response to sound stimuli, a process known as electromotility. When sound waves enter the cochlea, they cause the outer hair cells to contract and elongate, which enhances the movement of the basilar membrane and facilitates the amplification of sound signals. This amplification is vital for improving auditory sensitivity, particularly for softer sounds, and it enhances frequency selectivity, which allows us to distinguish between different pitches. The mechanical actions of the outer hair cells effectively boost the amplitude of sound vibrations before they are transmitted to the inner hair cells, which are primarily responsible for transmitting auditory information to the brain. While inner hair cells are critical for sending sound information, supporting cells do not directly participate in sound amplification, and auditory neurons serve as conduits for nerve impulses rather than amplifying sound waves. Thus, the correct choice highlights the significant function of outer hair cells in the cochlea's auditory mechanism.