Indeed, the fact that the two sine waves have the same amplitude when they are close to the ear accounts for the indistinguishability of the two sounds. Nevertheless, the two sounds, even if indistinguishable, are distinct, whereas the two sound waves are not. A way to put the difficulty is as follows: a loud sinusoid heard at a distance is still a loud sinusoid; but the corresponding sound waves decrease in amplitude. As we have seen discussing proximal theories, we can make perfect sense of th