Pellets de madera

Disturbance event theory seems to be the best distal event theory so far. It does not tie sounds to event sources. It allows non-vibratory sounds and accepts the medium-dependence of sounds. Nonetheless, there are two unsolved problems.

First, the identification of sounds with disturbance events, when conjoined with the distinction between disturbance events and transmission events, fails to give a sat-isfactory account of the sounds of wind instruments. Second, the thought that event sources are also experienced auditorily leads to the question of whether sounds as disturbance events are experienced as related to event sources, and a positive an-swer to this question can hardly be squared with the unity and simplicity of the phenomenal character of our auditory experience.

These two problems may not be fatal. The first one may be solvable by a better analysis of the distinction between disturbance events and transmission events. The second one may be avoided by rejecting that event sources are audito-rily experienced. While I see no reason to block these two responses, both are not attractive. The distinction between disturbance events and transmission events looks clear enough, hence any attempt to further clarify it would likely be ad hoc.

As for the assumption that event sources are experienced, it is more plausible than its contrary.

Apart from these two problems, I would like to discuss a problem, not only for disturbance event theory, but generally for all distal event theories we have dis-cussed thus far. It is the same objection from echo experiences we disdis-cussed in

§5.1.3 concerning object property theory. Let us look at how proponents of distal event theory understand echoes and echo experiences.

Both event source theory and event property theory have not been discussed concerning echoes and echo experiences. Casati and Dokic (2009, p. 99) simply dismiss echo experiences as clear cases of spatial misrepresentation. The only in-depth discussion is available in O’Callaghan (2007b),²⁹ so I will focus on it.

O’Callaghan (ibid., pp. 124-125) holds that an echo is a primary sound re-encountered, and an echo experience is just a distorted experience of the primary sound with distortions of its location in time and space as well as its auditory prop-erties. There is a further condition that a distinctive echo experience, in which the echo is experienced as causally related to the primary sound, requires that there is an interval of a certain length between the arrival times of the direct wave and the reflected wave (ibid., p. 127).

To evaluate O’Callaghan’s view, let us consider the following case of a dis-tinctive echo experience. Suppose there is an explosion. One part of the generated compression wave goes straight to my location, while another part of it goes to a wall behind me, reflects, and arrives at my location one second after the arrival of the direct wave. Both the direct wave and the reflected wave cause me to have an auditory experience. Suppose then I say to my friend, “I hear an echo one second after I hear an explosion.” How would O’Callaghan interpret this sentence?

29 The account presented in O’Callaghan (2007b) is basically the same as the one in O’Callaghan (2007a). To simplify things, I reference the former work only.

To begin with, O’Callaghan can treat what I say as reporting some subjec-tive fact about my two experiences of the very same explosion—i.e. that there is a one-second delay between my first and second experiences of the same explosion.

But this does not seem to exhaust the content of my experience.

I contend that the delay experienced is as objective as any time gap between two independent audible events. In an alternative scenario, two explosions under appropriate circumstances may produce in me an indistinguishable experience of a one-second delay. It would be implausible to allow objective experiential content in this alternative case only but not in the echo case.

O’Callaghan may try to explain this objectivity in the experienced delay by saying that it represents a one-second delay between two distal events—the explo-sion and the reflection of the wave. Unfortunately, it would be too unlikely for such an experience to be veridical. A delay of very different length between the explo-sion and the reflection can also result in the same experienced length of it if the explosion, the reflective surface, and the perceiver are in a suitable spatial arrange-ment. For such an experience to be veridical, the explosion and the reflective sur-face has to be equally far away from the perceiver, with the distance not measured in spatial terms but in the time needed for the compression wave to cover it.³⁰ This condition is, however, rarely met. When I experience a one-second delay, I can only hope that I am lucky enough to be in such a rare situation such that my experience veridically represents the delay between the two distal events.

Most if not all people who are not born deaf have in their lifetime at least some instances of distinctive echo experience. However, this explanation implies that only a very tiny subset of such experiences of a delay is veridical. Most people would have nothing objectively true in their relevant experiences. This is implausi-ble.

There is still another alternative explanation. Instead of treating the experi-enced delay as representing a delay between two distal events, this alternative says that it represents a delay between two proximal events—the arrival at my ears of the direct compression wave and that of the reflected compression wave. If I am

30 Since the speed of compression waves varies with many factors in the medium, measuring the distance in spatial terms would tremendously reduce the generality of the veridicality condition mentioned in the text.

right about the objectivity of the experienced delay, this alternative seems to be a much better explanation than the previous one. Assuming that my auditory system is working properly, the length of the experienced delay is guaranteed to match the objective delay between the arrival times of the primary wave and the reflected wave. Even if the explosion and the reflection of the compression wave are not separated by one second, my experience would not thereby have nothing objec-tively true.

However, this alternative is unavailable for O’Callaghan. The two proximal events of the arrivals of the direct and reflected waves are not experienced in his view, since he denies that compression waves are objects of auditory experiences (ibid., pp. 69, 163), and a perceiver cannot experience the arrival of compression waves without experiencing the compression waves. Therefore, he cannot explain the objectivity of the experienced delay in this way.

I do not deny that my experienced delay most likely misrepresents a time gap between two distal events. All I need to show is that my experience has some remaining objective content which can only be explained if we allow the proximal events of the arrivals of compression waves to be experienced. This would be enough to show that O’Callaghan’s view, and arguably other distal theories of sound, cannot afford a satisfactory explanation of the relevant experience. To achieve this aim, we consider another example.

Suppose I connect an electronic metronome to a loudspeaker placed at a certain distance from a large concrete wall on the opposite side of an open field.

The metronome is set to 60 beats per minute. Standing right next to the loudspeaker, the echoes reflected from the wall are not synchronised to the ticks directly from the loudspeaker. I then move closer to the wall, such that the echoes can reach me earlier, while the ticks from the loudspeaker take longer to hit my eardrums. The intervals between the ticks and the echoes then narrow down, and finally they are perfectly in sync.

In this example, I do not merely synchronise my subjective experiences of the ticks and the echoes. If I have carried a microphone during the whole process, it can also record the synchronisation process between two different things. How-ever, neither the loudspeaker’s ticking nor the reflection of compression waves at the wall are changed by my movement across the field. Therefore, the things which are synchronised are not these distal events. Rather, they are the proximal events of

the arrivals of the direct waves and the reflected waves. If O’Callaghan is correct that such proximal events are not experienced, no satisfactory explanation of this scenario can be offered. Therefore, we should reject O’Callaghan’s view and allow that proximal events of wave arrival can be experienced auditorily.

To be fair, this conclusion does not necessarily show that O’Callaghan’s theory of sound is false. After all, I have only shown that his view of our echo experiences should be rejected. Perhaps sounds are nonetheless distal events, and we experience proximal events in addition to them. However, a crucial step in O’Callaghan’s argument for his disturbance event theory is the denial that compres-sion waves are experienced. If it is allowed that comprescompres-sion waves are experienced alongside distal events, there is no obvious reason to prefer distal theory over wave theory. All the alleged experiential evidence, such as the perceived distal locations of sounds, can be characterised instead by saying that those are not locations of sounds as compression waves but the locations of the distal events experienced.

Furthermore, to the extent that distal theories of sound suffer from the problems discussed in the previous subsections, if wave theory can avoid those problems, as I am going to show in next chapter, we should accept wave theory instead. Before that, I end this section with a criticism of a very different distal theory—the sec-ondary event theory.