 Another more serious objection contends that the events we seem to hear are ones that do not constitutively involve sounds or that might have taken place without sounds. For instance, we hear the collision, but the collision is something that could have occurred in a vacuum and not made a sound. (Note that this differs from the claim discussed below according to which sounds are identical with source events and so inaudibly exist in vacuums.) If so, the collision and the sound differ and the collision does not strictly include a sound. The collision therefore must have made the sound as a causal byproduct. This suggests that, strictly speaking, you could not hear that very collision event (since it causes the sound). The best response is to bite the bullet and accept that events that do occur or that could occur in vacuums cannot be heard since they include no sounds. This is not so bad, since you could hear a different, more encompassing event that includes a sound along with a collision. Alternatively, one might say the very same event that occurs in a vacuum also could occur in air, but that it would have involved a sound had it occurred in air. In that case, one can only hear such events when they occur in air and include a sound. The choice depends upon one’s metaphysics of events. In either case, it seems reasonable that token events that do not include sounds are inaudible.