Passage
Sound waves propagate through many conducting structures in the ear before they are transduced into neuronal signals. When sound waves reach the fluid-filled cochlea, they are detected by hair cells lining the basilar membrane. The cochlear spiral can be modeled as a resonator system because each section of the basilar membrane is sensitive to a specific frequency (Figure 1) .
Figure 1 Amplitude pattern of the basilar membrane for different frequenciesPresbycusis (age-related hearing loss) results from a combination of factors that lessens an individual's mechanical and/or neurological sensitivity to sound. Pure tone audiometry (PTA) is used to determine an individual's ability to detect different sound frequencies and can be used to evaluate presbycusis. A "pure" tone is characterized by a single sinusoidal waveform. An audiogram plots the relative intensity required of a given frequency to be detected by the individual (Figure 2) .
Figure 2 Audiogram of an elderly patient exhibiting presbycusis
-Hearing loss due to loud environments can be mitigated with noise-canceling earphones, which generate a waveform that reduces the intensity of ambient noise through wave interference. For the above sound wave, the waveform generated for complete noise cancellation will be:

Question

Passage
Sound waves propagate through many conducting structures in the ear before they are transduced into neuronal signals. When sound waves reach the fluid-filled cochlea, they are detected by hair cells lining the basilar membrane. The cochlear spiral can be modeled as a resonator system because each section of the basilar membrane is sensitive to a specific frequency (Figure 1) .

Figure 1 Amplitude pattern of the basilar membrane for different frequenciesPresbycusis (age-related hearing loss) results from a combination of factors that lessens an individual's mechanical and/or neurological sensitivity to sound. Pure tone audiometry (PTA) is used to determine an individual's ability to detect different sound frequencies and can be used to evaluate presbycusis. A "pure" tone is characterized by a single sinusoidal waveform. An audiogram plots the relative intensity required of a given frequency to be detected by the individual (Figure 2) .

Figure 2 Audiogram of an elderly patient exhibiting presbycusis
-Hearing loss due to loud environments can be mitigated with noise-canceling earphones, which generate a waveform that reduces the intensity of ambient noise through wave interference.

For the above sound wave, the waveform generated for complete noise cancellation will be:

Quizplus · Accepted Answer

11ecba2d_12ed_50da_a3bf_b9372dbce383_MD0008_00 The intensity (perceived loudness) of a sound wave is related to its amplitude (displacement). When more than one wave occupies the same space, wave interference occurs to create one wave that is the sum of the individual waves. Constructive interference occurs when the sum of the amplitudes results in a larger amplitude. Destructive interference occurs when the sum of the amplitudes results in a smaller amplitude. Complete noise cancellation occurs when the generated sound wave destructively interferes with the original wave at all points, resulting in an amplitude of zero. A wave that is flipped across the x-axis will have equal and opposite amplitudes at each point along the wave. The sum of two equal and opposite amplitudes is zero, resulting in total destructive interference and canceling all noise. (Choice A) The phase of a wave is the measure of the horizontal offset from a reference wave. When the given wave is superimposed with a copy of itself shifted by half a wavelength, it will be only partially canceled. (Choice C) The frequency of a wave is the number of cycles that pass a fixed point per unit time. When a wave is superimposed with a copy of itself with double the frequency, both constructive and destructive interference can occur. (Choice D) A wave summed with an exact copy of itself will result in constructive interference at all points throughout the wave. Educational objective: Constructive interference occurs when the sum of the amplitudes results in a larger amplitude. Destructive interference occurs when the sum of the amplitudes results in a smaller amplitude. A wave that is combined with a copy of itself that has been flipped across the x-axis would result in complete destructive interference.

Passage Sound Waves Propagate Through Many Conducting Structures in the Ear