 In some conditions, however, it can be difficult for us to tell a loud sound in the distance from a soft sound nearby, because in the part of space closer to our ears the sound waves that reach us and correspond to the two sounds can have the same amplitude. (This only holds for an ideal case of a long lasting sine wave with no sharp attack. This type of sound is practically distance-proof because having a single component, the only possible variation is in amplitude, and no other spectral differences arise.)