Final answer:
The tones we can hear are placed along the basilar membrane within our ears, corresponding to the frequency of the sound. The place theory of pitch perception suggests that different parts of the membrane are sensitive to different frequencies, which defines how we hear tones.
Step-by-step explanation:
The area where the tones we can hear are placed is related to the frequency and intensity of sounds that the human ear can perceive, specifically within the auditory range of the basilar membrane. The shaded region in Figure 17.35 represents the majority of conversational sounds. These sounds are centered within a frequency range that is most sensitive to average human hearing. Furthermore, the place theory of pitch perception supports the idea that different portions of the basilar membrane respond to varying frequencies, with the base responding to high frequencies and the tip responding to low frequencies. Therefore, tones we hear are placed along this membrane depending on their pitch, which is critical for tasks like understanding speech and identifying different musical instruments.
Hearing losses measured in phons can affect how quiet or indistinct these tones seem. For example, a 40-phon hearing loss would make conversations sound very quiet, whereas a 60-phon hearing loss would significantly impair the ability to hear higher frequencies, and thus, to understand normal conversational speech, especially from female voices.