Final answer:
Given the small size of the mammal's auditory canal, one might suspect that the animal's hearing is most sensitive at a higher frequency, potentially around 4000 Hz or higher, similar to the peak human hearing sensitivity at 2000 to 5000 Hz.
Step-by-step explanation:
The question asks which frequency a newly discovered small mammal might be most sensitive to, given an auditory canal length of 0.5 cm. Hearing sensitivity in animals correlates with the physical dimensions of their auditory structures, and higher frequency sounds tend to be more effectively received by smaller structures like a short auditory canal. Considering human hearing sensitivity is at its peak at frequencies of 2000 to 5000 Hz, and the given length is quite small, the mammal's hearing sensitivity might similarly be at a higher frequency. However, without more specific information on the physiology of the new mammal and the acoustical properties of its auditory system, we can only hypothesize. If we follow the logic of resonant frequencies and the size of their auditory canals, we might predict that this animal's hearing is most sensitive at a higher frequency, which could be in the range of 4000 Hz or even higher.
The frequency that the new small mammal's hearing is most sensitive to can be estimated based on the range of frequencies that humans are capable of hearing. Humans can hear frequencies from 20 Hz to 20,000 Hz. We can use the fact that the minimum amount by which frequencies need to vary for humans to distinguish two separate sounds is 100 Hz. Since the auditory canal of the new small mammal is measured to be 0.5 cm, we can assume that the size of the mammal's auditory system is similar to that of humans. Therefore, we can estimate that the frequency to which the new mammal's hearing is most sensitive is in the middle of the range of frequencies humans can hear, which is around 10,000 Hz.