# **Audible Presence** ## **1\. Image and Appearance** ### **1.1 Visual Images** The zebra on the cover of *National Geographic* does not look like you could reach out and touch it. It is tempting to say that what you see looks like a zebra, but You are presented with the appearance of a zebra, but it is clear that it does not belong to a real-life, flesh and blood zebra that you could reach out and pet. One way of putting this is to say that real-life objects look *materially present*, but depictions of them do not. Versions of this idea are fairly common in the philosophical literature on image perception. Martin says that the things we see in pictures are mere *visibilia*, in that, like rainbows and shadows, they do not look as though they have an “existence and impact...beyond the visible realm” (2012, p. 334); Matthen, describes depicted objects as “display\[ing\] certain important visual characteristics of material objects while at the same time looking as if they are not actually material objects''(2018, p. 323; see also 2010); and Noë says that “Pictures enable us to undergo a visual sense of the presence of something in its manifest absence”(2015, p. 85; see also, for example, Nanay 2015, Wiessing 2010, Hopkins 1998, Ferretti 2016). In this paper I will argue that auditory experience divides the world up in much the same way that visual experience does. If I strike a real-life bell or strum a real-life guitar, these events will *sound* materially present –what you hear will auditorily appear to have an existence in and impact on the material realm; when recordings of events like these are played through stereo speakers or headphones, they will, almost always, sound absent –what you hear will auditorily appear as though it does *not* have an existence and impact beyond the audible realm. If this is correct then auditory experience is rich in the same way that visual experience is rich: it asserts whether or not the events we hear are taking place in the material world. It would also go some way towards showing that there are such things as *auditory images*. Indeed, on one view of what images are, it would go all of the way. According to Martin, all a visual image is is something which “presents the appearance of something which it does not exemplify” (2012, p. 343), and so if a recording of a guitar being strummed is recognisably a strumming, yet manifestly, audibly, absent, we have an example of an unexemplified auditory appearance, and thus an auditory image. However, it is more common to think that there is more to being an image than simply presenting an unexemplified appearance. Often, the claim that depicted objects look absent is presented as part of the idea that there are two ‘folds’ to image experience: looking at a photo, you not only see a manifestly absent object, but also a manifestly *present* picture surface: we see the absent zebra *and* the glossy cover of the magazine, with the experience of one seeming to be tied up –somehow– with the experience of the other.[^1] While I will say a little more about the possibility of auditory twofoldness and Martin’s account of images in Section 5, my main focus here will be on whether or not things can sound present or absent and so, as regards images, the arguments that follow can be read in a stronger or weaker way. If one agrees with Martin as to what makes images images, then the following can be taken as an argument for their being auditory images. If one disagrees, and thinks that something like twofoldness must be involved in image experience, then what follows can be thought of as providing *half* of an argument for auditory images, with further work required to show that listeners can on some occasions hear some auditory analog of a picture surface as well. ### **1.2 Auditory Austerity** The idea that auditory experience divides what we hear into the materially present and the materially absent is explicitly denied by Martin, who says “audition does not provide the materials to generate a form of representation analogous to...visual images” (p. 344). Nudds (2018) agrees: #### The auditory world does not seem to contain purely auditory objects alongside the ordinary environmental events that we take ourselves to hear...Some audible objects may in fact turn out to be more than mere audibilia, but that fact about them is not auditorily manifest to us, and there need be no audibly apparent difference between an auditory scene that contains audible environmental events and one that contains only pure audibilia. (ibid., p. 60\) Nudds is not denying the possibility that we are able to hear real-life events involving actual material objects, only that the materiality, or lack thereof, of what we hear is not marked in auditory phenomenology: material objects look different to the objects we see in photographs, but real-life events do not sound different to recordings. Put another way, Nudds and Martin think that audition is somewhat impoverished compared to vision: visual appearances are determined both by ‘ordinary’ visual features such as such as colour and shape, *and* material presence (or lack thereof), whereas the appearance of the things we hear is fixed solely by “acoustic features...such as pitch, loudness, and timbre” which do not reveal “how their bearers would extend into physical space or interact with material objects” (ibid.). In what follows I will argue that we have good reasons to reject this *austere* view of auditory experience. The appearance of the things we hear is not only fixed by their acoustic features but also by their sounding, or not sounding, materially present: real-life events sound like they have an existence and impact beyond the audible realm, recordings of events do not. In the next section I will deal with a preliminary objection to this aim: it might just seem obvious that the pitch, timbre, and loudness are the only features that fix auditory appearances. I will give some reasons for thinking that it is not as obvious as we might think. In Section 3 I will argue that real-life events do, in fact, have a different auditory appearance to recordings. In Section 4 I will give some reasons for thinking that this difference is a matter of real-life events, but not recordings, sounding materially present. ## **2 Austerity is not Obvious** ### **2.1 Austerity and Common Sense** Prima facie, the austere view of auditory experience might seem very plausible indeed. We might even think that it is obvious that auditory appearances are entirely fixed by pitch, timbre, and loudness. The aim of this section is simply to show that it is not as obvious as one might think. One reason why we might assume that austerity is correct is that it fits with our common sense ideas about auditory perception, which I take to be something like the following: we hear sounds, sounds are sound waves, and sounds instantiate the properties pitch, timbre, and loudness. In and of itself, however, common sense cannot be our sole reason for accepting or rejecting any philosophical claim. This is especially true when it comes to auditory perception given that almost all philosophical theories of audition depart quite considerably from our everyday ideas about what we hear. First, according to almost all contemporary views of auditory perception we not only hear sounds, but also *sound sources* –the movements and interactions of material objects which produce sound waves. That is, we do not simply hear a chime and judge that a bell has been struck but hear the chime *and* the strike, with the hearing of one somehow connected up to the hearing of the other.[^2] Another way in which many philosophical accounts of audition depart from common sense is that they do not identify sounds with sound waves. To mention three examples, sounds have been identified with vibrations (Casati and Dokic 1994), disturbances of the air (or some other medium) surrounding to vibrating objects (O’Callaghan 2007), and stable, dispositional properties of material objects (Kulvicki 2008). The fact that these ideas depart from our unreflective ideas about what we hear is no reason to dismiss them out of hand; similarly, we should not assume that austerity is true simply because it fits with our common sense intuitions. A related reason for accepting austerity might go as follows. If we think about the physical properties of sound waves, they have three obvious features: frequency, spectral composition, and amplitude. We might therefore think that auditory appearance is fixed by audible properties that supervene on, or are identical with, each of these features, namely pitch, timbre and loudness. However, regardless of whether sounds should be identified with sound waves, there is no reason to think that auditory appearances are fixed by these features and no others. It is quite common to argue (although not uncontroversial) that objects can be seen to bear properties other than those that match up one to one with their physical properties, such as natural kind properties (e.g. being a pine tree), aesthetic properties (being beautiful) or dispositional properties (being edible). Indeed, if we were to say that visual appearances are fixed solely by low-level physical properties of objects, this would seem to block the idea that things can look or not look materially present. There is no reason to think that things are any different for audition. ### **2.2 No Auditory Eden** Another reason we might think that austerity is correct is that it is *introspectively* *obvious* that it is correct. That is, we might think that when we attend to our auditory experience it is clear that the appearance of all the things we hear is fixed entirely by some combination of loudness, timbre, and pitch. However, just as we should not rely on common sense when evaluating the truth of a claim, neither should we rely too heavily on introspective seemings. If it were introspectively obvious which features or properties fix perceptual appearances then various controversies in the philosophy of perception would be solved at a stroke. It would be clear, for example, whether or not we see ‘higher level’ properties (REF), such as those mentioned in the previous paragraph, or whether we perceive ‘negativities’ such as empty space or silence (e.g. Sorenson 2008 and REF). Moreover, what little agreement there is about visual appearances has no counterpart in discussions of auditory phenomenology. Consider the following remarks by Chalmers (2010) on what visual experience is like: #### At some level, perception represents our world as an Edenic world, populated by perfect colors and shapes, with objects and properties that are revealed to us directly (p. 382)....Phenomenologically, it seems to us as if visual experience presents simple intrinsic qualities of objects in the world, spread out over the surface of the object (p.398) Some might baulk at the use of the word ‘representation’, and there are myriad views as to what colours are, but almost everyone would agree that this description gets something right about visual phenomenology: colours seem to be properties on the surfaces of objects. However, when it comes to auditory phenomenology, there is not even this much consensus. Nudds, for example, takes auditory phenomenology to reveal sounds as property bearing particulars, detachable from source events: #### Because sounds *appear to be individuals that instantiate properties* and can be individuated as such, I think it’s right to say that sounds appear to be independent of the material objects that produce them—independent, that is, of their sources (2013, p. 343; my emphasis). Leddington, on the other hand, describes auditory phenomenology in precisely the opposite way: “sounds auditorily seem bound to their sources qualitatively, as properties”[^3] (2014, p.330, see also p. 332). While other accounts of what sounds are (medium disturbances, vibrations etc.) rely on phenomenological seemings more or less than others, we can suppose that the proponents of all of them believe their view to be at least *compatible* with how things seem auditorily. But if introspection does not make it obvious what sorts of things sounds are, it does not seem as if we should be any more confident that it reveals auditory appearances to be fixed by pitch, timbre, and loudness alone. Indeed, if there is disagreement as to whether sounds seem to be particulars or seem to be properties this means that there is also a disagreement as to what pitch, timbre, and loudness seem to be. If sounds appear to be individuals, then pitch, timbre and loudness would appear to be properties of sounds. But if sounds themselves appear to be properties, then pitch, timbre, and loudness would seem to be something like *qualities* which *constitute* these properties –similar to how hue, saturation, and brightness constitute colours properties (Leddington). The moral that I think we should take from these considerations is that we should be generally wary of relying on introspection to make strong claims about what we do and do not perceive, but especially so in the auditory case. In the absence of any further arguments in favour of austerity, it seems we should at least consider the possibility that material presence, or lack thereof, contributes to the appearances of the things we hear. In the next two sections I will put forward my reasons for thinking that such a feature, or lack of it, *does* contribute to the appearance of the things we hear. ## **3\. The Real and The Recorded** In this section I shall argue that real-life events and recordings of events differ in their auditory appearance, in the next I will argue that this is a matter of the former but not the latter sounding materially present. The first reason for thinking that recordings and real-life events differ in appearance is that we can, almost always, be quite sure whether what we are listening to is one or the other. The second is that the sensory stimulation produced by recordings of events differs significantly from that produced by real-life events in almost all circumstances. ### **3.1 Believing our Ears** In the following passage, Nudds suggests that stereo speakers are capable of generating auditory illusions: #### stereo loudspeakers...produce experiences of sounds that don’t correspond to events that produced them...To hear a sound that doesn’t correspond to what produced it is to experience a kind of auditory illusion: that of merely seeming to hear sound-producing events. It is possible to have the auditory experience of someone coughing over on your left when in fact there’s no one there. (REF) Illusions are deceptive perceptual experiences. Unless you have some reason to believe that what you are experiencing is an illusion, you will be fooled into thinking that the world is one way when it is in fact another. Do stereo speakers, or other types of playback device, elicit experiences capable of misleading us in this way? The answer, I think, is yes, but very, very rarely. The following I take to be uncontroversial. In most ordinary situations we can effortlessly differentiate the real from the recorded. On a train, it is obvious that the conductor is making his announcement over the public address system and not from the back of the carriage; in a bar, it is easy to tell that the song you hear is coming from a live band and not the jukebox; at home, you feel no alarm at the gunshots on the other side of the wall because it is clear that they are coming from your neighbour’s TV. Regardless of whether the real and the recorded sound different, we are very often very sure as to whether we are hearing one or the other. One might be tempted to argue that in cases like these the reason why we realise we are not hearing a real event is due to the low quality of the speakers which are producing the sound waves. Listeners might be tipped off by the crackle that the PA system adds to the conductor’s voice, or the hum that accompanies each song played through the jukebox, but when sound waves are produced by high quality speakers their auditory experiences would be indistinguishable from those produced by real-life events. While this type of response might seem compelling initially, it becomes less so when we consider how often we come across high quality speakers, and how infrequently we are fooled by them. Imagine playing a high quality digital copy (that is, encoded in a ‘lossless’ format such as a FLAC or a WAV file) of the stereo mix of *A Love Supreme* by John Coltrane on your brand new stereo system. Your stereo is high-end, although fairly unremarkable for the 21st century, in that it has “very low levels of distortion, a wide frequency range, a flat frequency response, and low noise, with specifications that match or exceed the limits of human perception” (Rumsey 2002, p. 652\).[^4] In other words, for any recording you play on it, your stereo will be able to produce sound waves with the same *spectral composition* (the same combination of component frequencies) as the sound waves produced by the musicians’ instruments when the track was originally recorded.[^5] Unlike an old transistor radio, your stereo does not cut out low frequencies, and unlike the souped-up, window-rattling sound system that a teenager might have in his car, neither does it boost the bass. If you blindfolded a friend and tried to pass off *A Love Supreme* as a real-life performance, would she be fooled? I contend that she almost certainly *would not*: it will still be obvious to her that she is hearing a recording and not a real-life band, and it would be obvious due to the *auditory appearance* of what she heard, rather than because she knows that Coltrane died in 1967, or because she knows that your living room is too small to contain a fully-equipped jazz quartet (plus two person audience).[^6] The reasons for my confidence that the recording will have a different appearance to a live performance will become clear in a moment, but first, consider the following: if you reflect on your own real-life experience, can you remember an occasion on which you mistook a recording for a real-life event, or a real-life event for a recording, or were unsure whether you were listening to one or the other? Can you remember witnessing someone else being fooled in this way, or being uncertain?[^7] I suspect the answer will be ‘no’. Occasionally, novels or films use the idea of listeners being deceived by recordings as a plot device,[^8] but we should not let the ease with which we can imagine someone being fooled by a recording lead us to think that such a thing happens very often at all. Even if you can remember times when you have been fooled, we might still ask why we encounter convincing auditory illusions so infrequently. Given how easily speakers in the 21st Century can replicate the spectral composition of sound waves, should we not find ourselves fooled, or at least unsure, fairly often? ### **3.2 Speakers and Sound Scenes** The reason why recordings and real-life events differ in auditory appearance is straightforward: in any sensory modality, the appearance of the things we perceive is determined in large part by the way in which our sense organs are stimulated, and the sensory stimulation produced by stereo speakers will almost always differ significantly from that produced by real-life events. Imagine that we are sitting in your kitchen. Standing in front of me and to my right, you open a can of cola. Some of the sound waves your action produces will travel directly to my ear drums. Because of where you are in relation to me, these direct sound waves will arrive at my right ear ever so slightly before they reach my left. Due to the extra travel distance, and the absorbent properties of my head, the sound waves at my left ear will also have a slightly lower amplitude, as well as slightly fewer high frequency components. Other sound waves that you produce will bounce off the walls, floor, or ceiling before they reach my ears, and will arrive slightly late because of this. They will also have been altered by the properties of the surfaces from which they reflected: the bare wooden flooring and plaster walls of your kitchen will absorb some frequency components and reflect others. If I start to move around the room as you are talking, this will have an effect on which sound waves reach which eardrum when: if I take a step to the right, the direct sound waves will reach my left ear slightly more quickly; moving away from you and towards the back of the room, will increase the time it takes for the direct sound waves to reach my ears, but decrease the travel time of the sound waves which reflect from the back wall. Now imagine that, for some reason, I am recording our encounter using two microphones attached just above my ears. They are powerful enough to pick up all of the sound waves rippling through the room, meaning that they are creating a near perfect copy of the patterns of stimulation at my ears, including the subtle, interaural differences in timing, frequency and amplitude, the slight delay between the arrival of the direct and indirect waves, and the ways that this stimulation varies as I move around. The result is a high quality stereo recording of you opening a can of cola in your kitchen. That evening, I decide to play the recording back on the stereo in my living room. However, while my speakers will produce sound waves with the same spectral composition as were produced originally, this will *not* lead to the same patterns of sensory stimulation at my ears. First, unless I am standing in exactly the right place in relation to my speakers, the sound waves at each ear will differ from the originals in terms of their arrival time, amplitude, and spectral composition. If I am standing closer to the left speaker than right, for example, the sound waves picked up by the left microphone will reach my ears slightly earlier, and with a slightly higher amplitude than they did in real life. This is due to the nature of sound propagation where sound amplitude diminishes over distance. Furthermore, the spectral composition — the mix of different frequencies — will also vary. This is because lower frequency sounds decrease in amplitude more slowly than higher frequency sounds as they travel, leading to a change in the balance of frequencies at the listener's ear. The further away I stand from the ‘sweet spot’ between the speakers, the more pronounced these differences will become. Even if I am standing in the perfect location I would also need to stay very still, as even slight turns of my head will affect which sound waves reach what ear when. Playing back the recording will also produce quite different patterns of reflected sound waves. Imagine that my living room is larger and has higher ceilings than your kitchen; there is a carpet on the floor and the walls are unplastered brick. The larger room leads to reflected sound waves taking longer to reach my ears than they did in your kitchen, and the carpet and brick will reflect and absorb different frequencies to your wooden floor and plaster walls. Moreover, all of the reflected sound waves which were originally recorded by my microphones are *themselves* being reproduced by my speakers: some of these will travel straight from the speakers to my ears, but some will bounce off the walls before they reach me, creating a secondary reverberation effect. Even in this very simple example, then, we can see that despite being able to replicate the spectral composition of sound waves it is very close to impossible for stereo speakers to recreate the sensory stimulation that would be produced by a real life event. It would be harder still to do so for more complex events such as a performance by the John Coltrane Quartet. In this section I have argued that we can differentiate the real from the recorded in almost all everyday situations, and that considerations about what stereo speakers can and cannot do provides us with an explanation as to why this is: playing recordings of events through stereo speakers is very unlikely to reproduce the patterns of sensory stimulation that are produced by real-life events. Differences in sensory stimulation lead to differences in perceptual appearance, so it is plausible that the reason why we are so good at differentiating the real from the recorded is that recordings have a different auditory appearance to real-life events. What has not yet been shown is that this difference in appearance is a matter of things sounding or not sounding present. This is what I shall try to do now. ## **4 Why Recordings Don’t Sound Real** Here is the story so far. We can differentiate the real from the recorded in almost all cases, and considerations about what stereo speakers can and cannot do provides us with an explanation as to how this is possible: stereo speakers are unable to replicate real-life sound scenes, meaning that listeners receive different sensory stimulation from a recording of a real-life event than they would from the original. Because differences in sensory stimulation plausibly lead to differences in perceptual appearance, this suggests that the reason why we are so good at differentiating the real from the recorded is that recordings have a different auditory appearance to real-life events. What has not yet been shown is that this difference in appearance is a matter of real-life events, but not recordings of them, sounding materially present. This is what I shall try to do here. My argument will be an inference to the best explanation. It is often suggested that the reason why the things we see in visual images do not look to be present is that they do not provide the visual system with the cues required *to locate them in egocentric space*. We will see that the sensory stimulation produced by stereo speakers is impoverished in much the same way: the sound scenes produced by recordings do not provide the cues that the auditory system needs to locate its objects in egocentric space. If this is correct then it is very plausible to think that a lack of egocentric location in the auditory case leads to precisely the same difference in appearance as it does in the visual case: recordings do not sound materially present. ### **4.1 Why depicted objects do not look present** **Jeep Version** We saw in Section 1 that while Martin’s views on images are somewhat heterodox, the idea that depicted objects look manifestly absent can be found in a variety of other accounts of image experience. Many of these accounts try to explain why this is by linking perceptual presence with the perception of objects as located in egocentric space: the zebra that we see on the front of *National Geographic* does not look like one that you could reach out and pet because your perceptual system does not represent it as having a determinate location. One example of this can be found in Nanay (REF) who draws on the dorsal/ventral account of perception to argue that: A minimal condition on performing perceptually guided actions on objects is representing the spatial location of this object in one’s egocentric space...If we couldn’t represent the spatial location of an object in our egocentric space, then we would have no idea which direction to reach out to grab it or use it for any other action. But, crucially, depicted objects are not represented in our egocentric space: the depicted space is not our egocentric space. * **Maybe add some more quotes** Similar ideas can be found in Matthen (Ref and Ref), Vishwanath (REF), Dokic (REF), and Ferrenti (REF),[^9] and there is good reason to think that something like this view is correct: given that depicted objects do not provide the visual system with the cues it requires to locate them within the material realm, we should not be surprised that they do not look as if they have an “existence and an impact” (Martin) within that realm. ### **4.2 Why Recordings Don’t Sound Real (new jeep version)** In Section 3, I introduced the example of a cough in a real-life situation and its recorded counterpart played back on high-end stereo equipment. I argued that, despite the quality of the equipment, the recorded cough does not sound the same as the real-life cough. The stereo speakers are unable to recreate the patterns of sensory stimulation at the listener's ears as would be produced by the real-life event of a cough. I now propose that this deficiency in the sensory stimulation produced by speakers is very similar to the deficiency in the visual stimulation produced by pictures: while recordings provide the cues required for the recognition of what we hear, they fail to provide the cues necessary for them to be heard as having a determinate location. We have just seen that in the case of pictures a lack of egocentric locatability leads to a lack of perceptual presence, and so it is plausible to think that the same is true when it comes to recordings. The auditory system is sensitive to interaural differences in the timing, frequency, and amplitude of sound waves, and is usually able to determine which sensory stimulation is caused by direct sound waves and which is caused by reflected, indirect sound waves. In real-life listening situations, such as hearing a cough in a kitchen, this information is used to determine where events are occurring in relation to the listener, as well as to gather information about the environment in which they are taking place (REF). Interaural differences, for instance, are used to determine the direction of a sound source: if the sound waves produced by a real-life cough reach my right ear slightly earlier, and with a slightly higher amplitude than my left, the auditory system registers this and contributes to my perception of the cough as coming from the right. Other cues for direction include regularities in the way that stimulation at each ear changes as the head moves (REF), and the characteristic ways in which the shape of the ears can affect the spectral character of sound waves depending on the direction from which they arrive (REF). In addition to direction, the auditory system calculates the distance at which an event is occurring, achieved in part by a sensitivity to the amplitude of sound waves and partly through comparing the ratio of direct to indirect (reflected) sound waves. Reflected sound waves are also used to determine more general information about the surrounding environment: the larger the environment, the longer the gap in arrival time between direct and direct waves (REF). However, these cues are significantly degraded when listening to a recording of a cough on stereo speakers. First, if a listener is not positioned directly between the speakers, the necessary interaural cues for proper sound location are lost. For instance, if the listener is slightly nearer to the left speaker than the right during the playback of the recorded cough, the sound from the left speaker will reach the listener's left ear a bit sooner and with a marginally higher intensity than the sound from the right speaker. This phenomenon, known as the "phantom image" effect, can cause the listener to perceive the sound as originating from the left, even if the sound was initially balanced between the two speakers in the stereo recording. Moreover, as the listener moves out of the sweet spot (the ideal listening position between the two speakers), the left and right acoustic pathways from the two loudspeakers to the listener’s ears become unequal. This causes the phantom image to appear to move and follow the listener towards the nearest speaker. At a certain point, when the sound level and arrival times from each loudspeaker are no longer perceived as equal at the listener’s ears, the phantom image becomes unstable and less focused, seeming to follow the listener to the closest speaker. Such distortion in perceived location can be particularly noticeable with transient sounds, which are brief, rapidly changing sounds like a cough. These sounds provide strong cues for sound localisation, but these cues can be easily distorted if the listener is not positioned equidistantly between the two speakers. Finally, the playback of the recorded cough will also produce different patterns of reflected sound waves. This is due to differences in room size, properties of the reflecting surfaces, and the fact that the recorded sound waves are being reflected again. This creates a secondary reverberation effect that was not present in the original situation of the real-life cough. This distortion of reflected sound waves thereby disrupts one of the primary cues that the auditory system uses to estimate both the distance of a source, and the size of the listener’s environment (REF). In conclusion, the sensory stimulation produced by the playback of a recorded cough on stereo speakers differs in several significant ways from the sensory stimulation produced by a real-life cough. These differences lead to distortions in the perceived location of the sound source, and thus, to a lack of perceptual presence. ### **Headphone Listening** Let’s now consider another common way of listening: through headphones. One might assume that headphones would outperform stereo speakers in terms of conveying a sense of egocentric location and thus perceptual presence. After all, stereo headphones can more accurately reproduce the sound waves that reach each ear. Regardless of a listener's position in a room, the sound waves reaching the eardrums remain consistent. Moreover, there's no disruption to the reflected sound waves as all sound waves travel directly from the headphones to the ears, unlike with stereo speakers where some sound waves bounce off nearby surfaces. However, it is clear that headphones do not provide entirely realistic cues for spatial hearing. Listening to music on headphones doesn't mimic the experience of a live performance; instead, the music seems to be occurring inside your head. The primary reason for this internalized sound perception is the invariability of stimulation. As you move your head or change your location, the sound waves remain constant. Without any additional processing, synthesized binaural signals presented over headphones result in a static listening experience. As a listener moves their head, the auditory scene follows along, leading to a less natural listening experience and creating an internal head localization (IHL) effect. Other factors contributing to the internalized sound perception include unnatural bone conduction and pressure on the head caused by the headphones, as well as the natural resonances of microphones and headphones. Let us turn to another very common way of listening: headphones * We might think that headphones will fare better than stereo speakers in allowing for the hearing of egocentric location and perceptual presence. * After all, stereo headphones can recreate more precisely the soundwaves which hit each of your ears: * Interaural distortions will not occur, as regardless of where a listener is standing in a room, there will be no change in the sound waves that reach her eardrums. * Neither will there be any disruption to the reflected sound waves: whereas some of the sound waves produced by stereo speakers will bounce off the nearby surfaces, in headphone listening all of the sound waves will travel directly from the headphones to the ears. * However, it is obvious that headphones do not provide us with entirely realistic cues for spatial hearing. Listening to music on headphones does not sound like listening to a live performance; rather, the music will sound like it is taking place in your head. Explanations as to why headphone listening sounds like it is happening in your head: The principle reason for this is the invariability of stimulation: sound waves to not vary as you move your head or walk around. Page 41: "Without any additional processing, synthesized binaural signals presented over headphones will result in a static listening experience, where the listener’s head motion will not be taken into account and as a listener moves their head, the auditory scene follows along. This leads to a less natural listening experience and can induce IHL." Page 41: "To create a more natural listening environment, and a better sense of immersion and presence, a compensation for the listener’s head orientation and location change must be accounted for so that a virtual sound source will remain firmly in place when a listener moves their head—as it does in the natural listening environment." Page 41: "In a virtual auditory environment, knowledge about the listener’s location and orientation can be used to compensate for any location change. To do this, the position of the head must be tracked, and the location of the virtual sound source must be updated according to the position of the listener, and the desired location of the source." Other reasons include: 1. an unnatural bone conduction and pressure on the head caused by the headphones, 2. natural resonances of microphones and headphones **Final bit of this section:** * In the last three sections we have seen that there is good reason to think that auditory perception divides the world up into the present and non-present. We can almost always here tell whether we are listening to a real-life event or a recording, and that the sensory stimulation provided by stereo speakers and headphones does not allow for the things we hear in recordings to be heard as having a determinate spatial location. Given that a lack of determinate spatial location is put forward as the reason that depicted objects do not look real, it seems xxx * One thing that should be emphasised here is that cases my arguments are not vulnerable to counter examples in which a listener \*is\* fooled by a recording. I do not deny that this is possible, there are devices that can make recordings sound as though they are real events, which, as audio technology evolves, will likely become available to more and more consumers. However, even if such devices became the most common way in which people listen to audio, surpassing headphones and stereo speakers in terms of popularity, this would not mean that presence is not marked in auditory perception. We can see this by considering something analogous happening in the case of vision and technology. Imagine that the technology evolves in such a way that it allows for hyper-realistic holograms that look materially present but are not (footnote Total Recall hologram and the holodeck in star trek). Even if ‘holovision’ surpassed traditional television and film as the world’s preferred way of consuming tv and film, this would not affect the claim that when people do look at photographs the things they see in them do not look real, and that one of the reasons for this, is that the things we see in pictures do not allow for them to be seen as located in egocentric space. ## **5\. Auditory Presence and Auditory Images** I have argued that there is such a thing as auditory presence, where does this leave the possibility of auditory images? As we saw in Section 1, on Martin’s account, seeing an image is nothing more than seeing an unexemplified appearance –a hologram of a zebra on martin’s account is a ‘pure image’ in that it has the look of a zebra, but at the same time is clearly, perceivably, not an actual zebra. The experience engendered by stereo speakers provides an auditory analog to seeing a hologram: what we hear has the sound of a jazz quartet, but at the same is clearly, audibly, not an actual jazz quartet. In fact, the auditory case arguably provides a better exemplar of a pure image than the visual one. If we look at how Martin describes holograms we see that he might be accused of sneaking twofoldness in through the back door: #### The appearance it has in common with the object of which it is an image is a matter of shape, size and colour. But one does not normally simply see colour, one sees colour as light, film, or surface. As *manifestly a creature of light*, the hologram possesses no solid surfaces to have colour—but one does not see it as merely having coloured light or film colour, precisely because one can recognize the appearance of a solid object *in it*: hence one has the effect of the appearance of coloured surfaces seemingly both present and absent. (My emphasis) Even if the holographic zebra is not seen as being realised by anything material, it is, as Martin puts it, “manifestly a creature of light”, and so we might think that light itself is playing the role of the second fold. In contrast, if we listen to *A Love Supreme*, on high quality speakers there does not seem to be any second fold at all. We hear the appearance of a manifestly absent jazz quartet, but do not hear in such an event “in” any other fold. As mentioned earlier, Martin is something of an outlier when it comes to images, with the mainstream view being that twofoldness is a necessary part of image experience. Do we ever have an experience of auditory twofoldness? While answering this question has not been my main aim here I want to outline in the rest of this section how we might understand this possibility. Auditory twofoldness occurs, I suggest, on *bad* speakers, those which crackle or distort at high amplitudes, cut out some portion of the low or high end frequencies, or which add an underlying hiss to whatever is played through them. Consider how John Coltrane might sound played over the tiny, tinny speaker of a transistor radio, or a crackly mobile phone. Here, you are still presented with the audible appearance of a jazz performance, and –simultaneously– some crackliness and tinniness. Why should we think of this as a twofold experience? * **The reason why is** In his 1998 Hopkins tries to capture the distinctive phenomenology of twofold experience as follows:seeing-in is “an experience whose content somehow includes the picture’s object” #### seeing-in remains a way of seeing the picture What’s more, your experience of the jazz performance seems to be somehow ‘mixed up with’ an experience of the crackly speaker itself. **Auditory Twofoldness** * * Irrespective of this possibility, we might still wonder whether there is an auditory equivalent of twofoldness: are there cases in which we hear something which manifestly lacks physical presence, being presented by something which manifestly does? * I think that auditory twofoldness is a possibility, but will here limit myself to a tentative sketch. * I have so far mainly focussed on hearing recordings played through high quality speakers (**reminder of how they are good),** * * ### **4.3 Other Playback Devices** So far, I have ignored one of the most common ways for sound waves to be reproduced: headphones. We saw in 3.2 some of the reasons why stereo speakers cannot replicate real-life patterns of sensory stimulation: the listener has to be at a very specific spot between the two speakers, and sound waves reflected from the walls of the listening room reach the eardrums as well as sound waves from the speakers. Listening on headphones, on the other hand, would avoid these sorts of problems: interaural differences in arrival time, amplitude, and frequency will not be affected by the location of the listener; no errant, reflected, sound waves will find their way to the listener’s ears. * On the other hand, headphone listening does not usually produce convincing auditory illusions: even on excellent headphones, listening to *A Love Supreme* does not sound like a real-life jazz performance is taking place nearby; rather, it sounds like it is taking place between your ears. * This is because, despite reproducing some of the cues we require for egocentric location, headphones do not produce all of them. * First, sensory stimulation does not vary in a realistic way if a listener turns her head; indeed, it does not vary at all. * Second, headphone listening does not reproduce the location cues provided by the pinna... #### Quote about headphones from the spatial audio book #### There are many theories speculating the cause of IHL. These theories include: 1\) an unnatural bone conduction and pressure on the head caused by the headphones (Sone, Ebata & Tada- moto, 1968), 2\) the invariability of the signal under non-static head conditions, and 3\) natu- ral resonances of microphones and headphones (Blauert, 1983\) as well as various theories of reproduction equipment, e.g. coupling between the ear and the headphone. The understanding of the cause of IHL was advanced with studies performed by Reichart and Haustein in 1968, as reported by Blauert (1983). The two scientists concluded that IHL occurs under two conditions: 1\) when both ear signals are similar enough that the sound is fused into one auditory event, and 2\) when each of the two sources must be perceived to be originating close to the ear. They also suggested that the alteration or the elimination of the acoustical effect of the pinnae con- tributes to this effect. In other words, a highly distorted pinna cue may lead to IHL. A binaural reproduction system may distort a spatially processed signal for two reasons. First, a headphone reproduction system of even the highest quality has its own characteristic. Second, placing head- phones over a listener’s ears produces an acoustic cavity that has its own transfer function. Thus, compensating for the effect of the headphone and ensuring a true free-field representation of a signal can minimize (or eliminate) IHL. There is not one theory currently that can fully explain IHL, or predict its occurrence. However, presenting a more natural sound to the listener can * Audio engineers are getting better at creating illusions * Give a very brief description of binaural audio * It is possible that in the future auditory illusions will be more common * This however, in no way counts against the arguments I have made in this paper. * What I have shown is that we do have experiences which are recognisably of an event (have the appearance of a cough, or a jazz performance) but which we do not mistake for an actually occurring event. * Even if auditory illusions were already a common occurrence, it would still be enough to show that they can occur in particular circumstances to disprove Martin’s claim that audition does not have “the materials to generate a form of representation analogous to the visual images” (p. 344). ## **5\. Pure and Twofold Auditory Images** **Introduction: I have shown what I wanted to.** * In Section 2 I argued that the possibility of auditory images should not be dismissed out of hand. * In Section 3 we saw that we can almost always differentiate between real-life events and recording, and that there are good reasons for thinking that this is due to a difference in auditory appearance. * In Section 4 I put forward reasons for thinking that this difference is a matter of real-life events, but not recordings, *sounding present*. * If this is correct, then, *pace* Martin, audition does have the materials to “​​generate a form of representation analogous to the visual images”. * **Auditory Images make for better examples of pure images than holograms** * I mentioned in Section 1, that Martin thinks of holograms as pure images: manifestly unexemplified appearances which do not seem to be being realised by any sort of material object. * * * Recall the dorsal ventral stuff from Nanay and Ferretti. On both their accounts while the depicted object is not represented dorsally, the picture surface is. It is represented as having some determinate location in egocentric space. * Same thing with the phone or the radio. You do not hear the saxophone as playing in some determinate location, but you *do* hear the phone to have a determinate location. * I do not pretend that this is anything like a complete account. In particular, more would need to be said as to whether the connection between hearing the speaker and hearing what is playing through the speaker is very much like seeing a zebra as being *instantiated by* the marks on the magazine cover. ### **~~5.4 Summing Up~~** * ~~We can now see why it is plausible that recordings are heard as non-solid.~~ * ~~The sensory stimulation provided by recordings do not provide the cues necessary to locate the events heard in egocentric space.~~ * ~~The difference between hearing an actually occurring event and hearing a recording is that the former, but not the latter, appears to be located in egocentric space.~~ * ~~This distinction is what makes SD possible: your friend is not fooled by A Love Supreme because although she hears a jazz ensemble playing, she does not hear it to be playing in the same space, the same location, as she is.~~ * **~~What More Here?~~** Consider the sound scene that was instantiated when The John Coltrane Quartet recorded *A Love Supreme*’s opening track: *Part 1: Acknowledgement*: * The air surrounding the musicians would be a sea of sound waves of different frequencies and amplitudes, some * sound waves emanated from the musicians’ instruments and ripple through the room, * started to play, sound waves were produced by their instruments and began to ripple through the room, blending together as they did so. When they reached a wall, floor, ceiling, or the surface of some other object in the room (such as the body of one of the performers) some frequencies of sound waves were absorbed, and some reflected back across the room. This continued until the musicians stopped playing, and all the sound waves were absorbed. It is almost impossible for stereo speakers to replicate this sound scene, meaning that it is almost impossible for them to recreate the patterns of sensory stimulation that a listener would have enjoyed if they had been standing in Coltrane’s recording studio. * When it comes *Part 1: Acknowledgement* these sorts of differences will be magnified * Something about the stereo mix ## **Bibliography** * Casati, R., Di Bona, E., & Dokic, J. (2013). The Ockhamization of the event sources of sound. Analysis, 73(3), 462-466. * Hopkins, R. (2020). The Sculpted Image?. In Philosophy of Sculpture (pp. 187-205). Routledge. * Matthen, M. (2010). “Two Visual Systems and the Feeling Of Presence,” in N. Gangopadhyay, M. Madary and F. Spencer (eds) Perception, Action, and Consciousness: Sensorimotor Dynamics and the Two Visual Systems. Oxford: Oxford University Press, pp. 107–124. * Matthen, M. (2018). Ephemeral Vision. Perceptual Ephemera, 312-36. * Nanay, B. (2015). “Trompe l’oeil and the Dorsal/Ventral Account of Picture Perception,” Review of Philosophy and Psychology 6, pp. 181–197. DOI:10.1007/s13164-014-0219-y. * Nudds, M. (2018). The Unitary Nature of Sounds. Perceptual Ephemera, 50-67. * O'Callaghan, C. (2007). Sounds: a philosophical theory. OUP Oxford. ## **References** ## Ferretti, G. (2016). Visual Feeling of Presence. *Pacific Philosophical Quarterly*, 112–136. https://doi.org/10.1111/papq.12170 Martin, M. G. F. (2012). Sounds and Images. *The British Journal of Aesthetics*, *4*, 331–351. https://doi.org/10.1093/aesthj/ays036 Noë, A. (2012). *Varieties of Presence*. Harvard University Press. Plack, C. J. (2018). *The Sense of Hearing*. Routledge. Roginska, A., & Geluso, P. (2017). *Immersive Sound*. Taylor & Francis. Toole, F. E. (2017). *Sound Reproduction*. Routledge. Wiesing, L. (2010). *Artificial Presence*. Cultural Memory in the Present. [^1]: There are a multitude of accounts of exactly how twofold experiences should be characterised (e.g. Hopkins 1998; Nanay XXX; Someone else) [^2]: Various accounts as to how sound hearing relates to source hearing have been put forward. See, for example, O’Callaghan (2011); Casati et al. (2013); Kulvicki **(XX)**Leddington (2018); Nudds (2014); Young (2021). [^3]: Mention that he backs off on this claim a bit in later work. [^4]: I will focus for now on high quality stereo playback in this section and the next, as this might seem the most likely way of producing convincing auditory illusions, at least in most people’s everyday lives. I will consider other types of hi-fi equipment in Section 5\. [^5]: For simplicity, let us assume that *A Love Supreme* received minimal post-production work after the performances were recorded. [^6]: Thanks to **Laura Gow for pushing me on this.** [^7]: Again, I should emphasise that I am not claiming that *trompe l'oreille* experiences are impossible, only that they are exceedingly rare. [^8]: For example, *The Murder of Roger Ackroyd* by Agatha Christie (REF) [^9]: This is not to say that all of these authors agree on the details. MORE MORE