The brain is still actually receiving two sounds, and processes the time difference between each to produce the illusion of a sound localized in space! As the sound source moves toward our center front or rear the time differential between the ears decreases and the sound appears to move towards the center.
We are, at any point in time, only aware of the location of the sound in a single horizontal plane to the right or left. If it is a brief sound, we can't really ascertain whether its source is to our front or back, or above or below us. But if the sound persists, we will without realizing it make small adjustments of our head ears to sample several different planes and quickly zero in on the sound source. There are some sophisticated, if not minimal cues for location that do come from a single ear in the form of the resonance created in the Pinna.
This is discussed briefly with some references for anyone who is interested, in the notes below. There is one more contribution of Temporal Resolving Power, which I would like to point out. You might have noticed, if you have ever taped a lecture and listened to it later, that you were more aware of all the background noises than you were in the actual classroom.
This is because in the classroom, you were able to use sound localization to identify noise sources. When you listened to the tape, however, the sound source was all from one direction and figure-ground discrimination becomes a more difficult task. Hence, a person with one good ear may hear sounds as loudly and clearly as anyone else, but will experience more confusion and fatigue in a noisy environment. The same is true for someone with a hearing aid, which has only one microphone to pick up the sound signals.
Auditory Memory: Memory, of course, is a major component of our neurological armament. It is a massive process that is involved in almost all other cognitive skills. Scientists spend their lives studying it, and still we don't know the basic mechanisms involved.
But there is much information we do have, and we will look at some of this later. But for now we must acknowledge the role of memory specifically in the auditory process. Two things are critical in audition.
The auditory stimulus is transient, and the message is discursive. That means the signal is strung out in time. It doesn't hang around long enough for us to experience the entire message in one "sitting," like we can when we observe a picture.
In audition, it remains for the processes of memory to hold on to the pieces of the stimulus that have faded, so that we can deal with them as if we had the whole. Note that I said processes plural , because memory like language is a system of many sub processes. Of the many memory sub processes, we will mention two for now: Short-Term and Long-Term memory. Short-Term Memory, is the ability to hold on to the signal for short periods of time--from milliseconds to hours. It is not, however, a single process but a group of sub sub processes: Sensory, Perceptual and Wrote Memory.
Sensory short-term memory , pertains more to the action of the transducer. In many respects it is the counter part of after imagery in the visual but with a different purpose. Sensory short term memory holds the image from the transducer long enough for us to recognize is structure.
Without the after glow on a radar screen, for example, patterns would be difficult to discern. Sensory short-term memory performs the same purpose. It enables us to recognize sounds patterns, like phonemes. Perceptual short term memory, relates to our ability to retain strings of words while the brain decodes their phonological, morphological, syntactical, semantic and pragmatic significance. This is truly an amazing process! People often talk to us in long complicated sentences.
The meaning of any sentence can only be obtained from an analysis of the interrelation of all the words taken as a whole. The sentence must also be analyzed in terms of a sentence that may have occurred earlier in the conversation.
There may be 20 to 50 words in a sentence. We must hold on to the words, extract the meaning, and do it fast enough to be ready to receive the next sentence which comes right on it tm s heels, and the next and the next. What makes it truly amazing is that typically we are limited to approximately 7 bits of information for this short term memory process.
We obviously do more by using various organizational strategies. One important strategies is expectancy. It's interesting that most computers have some of this now in the form of word prediction. You start to type something and the word appears before you finish.
Context and and particularly grammar are important features of expectancy which broaden our input capacity. For a child or adult with severely limited short term memory say 4 or less bits in information and with few strategies to rely on, e.
I actually experienced a similar situatiion in Latin II class. I did well with Caesar who came, who saw and who conquered Gaul; and wrote about it in short sentences.
Here we read the works of Cicero who never wrote a short sentence, I am sure, under two pages long. I could never get a complete sentence into my all at once head. By the time I got to the verb phrase through all the relative clauses etc. My short term memory, I believe, would have to have been 21 bits to get the whole Latin Cicarian sentence. Granted I had a poor sense of the Latin grammar too, which didn't help my short-term memory.
But, I think I know now why Rome declined. They couldn't understand each other with these long sentences. Just kidding, Latin scholars. Auditory Perceptual short term memory is often tested in older children by having them repeat a series of numbers of increasing length. Wrote memory is the short term memory process we use to hold on to information long enough retain lists of items to get from the store, or facts to regurgitate on a test.
We use Wrote Memory to retain information long enough to be processed into Long-Term memory. Unlike perceptual short term memory which lasts for fractions of a second, this process can last for hours. It is also useful for holding on to information long enough to convert it into long term memory, but that is a later discussion.
There is much that we can do with our young children to develop perceptual and wrote memory skills. Reading to the child the infant too is a major positive step. Putting TV in the locked closet is another. Suffice it to say that the brain waves of a person watching the typical TV shows are similar to a person who is asleep. I see limited brain growth there--and a whole lot of wasted time where growth could have taken place..
There are many activities that will improve the short-term memory process. This episodic LTM decline, related to hearing loss, may be a cause of dementia. This remained a significant finding even though many background variables such as age, sex, race, education, diabetes mellitus, smoking, and hypertension were taken into account.
As has been shown, for some people with low WMC, signal processing that is too advanced impedes rather than helps cognitive processing of the signal. It is, in this context, important for scientists to develop reliable brain indices of cognitive disturbance and effort, which may improve hearing aid fitting.
Pupil-dilation and brain-oscillation measures are examples of these indices. Hopefully, future cognitive hearing aids can capitalize on such techniques — for example, by using the electrical signals detected in the brain to actually control the online amplification and signal processing in hearing aids.
From the new cognitive hearing science perspective, it would be equally important to evaluate episodic LTM of the contents of a conversation in noise, because these contents signal what kind of spare cognitive capacity the listener had while attempting to follow the conversation. Future studies also should evaluate the effects of WM training and, especially, whether any improvements in WMC transfer to other skills, such as speech understanding in noise tasks.
Scientists also can use longitudinal studies to examine the effects of WMC training and hearing aid use, as well as how these effects relate to or shield the brain from age-related cognitive decline. All of these applications are important for clinical audiologists, psychologists, and other hearing health-care practitioners to know about in order to optimize the communication potential of people with hearing loss.
Arehart, K. Working memory, age, and hearing loss: Susceptibility to hearing aid distortion. Ear and Hearing , 34 , — Arlinger, S. The emergence of cognitive hearing science. Scandinavian Journal of Psychology, 50 , — Lin, F. Hearing loss and incident dementia. Archives of Neurology, 68 , — Lunner, T. Interactions between cognition, compression, and listening conditions: Effects on speech-in-noise performance in a two-channel hearing aid.
Journal of the American Academy of Audiology , 18 , — Hearing loss is negatively related to episodic and semantic long-term memory but not to short-term memory.
Journal of Speech, Language, and Hearing Research , 54 , — The effect of functional hearing loss and age on long- and short-term visuospatial memory: Evidence from the UK biobank resource. Frontiers in Aging Neuroscience, 6. Frontiers in Systems Neuroscience, 7.
Cognitive hearing science: The legacy of Stuart Gatehouse. Trends in Amplification, 15 , — In we reported that the ability to recognize speech or other familiar sounds by listeners with normal hearing sensitivity appeared to be relatively distinct from spectral or temporal acuity or general intelligence.
J Acoust Soc Am. Individual differences in auditory abilities. Very interesting article. The customary science-based view holds that sounds are pressure waves that travel through a medium see also Sorensen On this account, sounds are caused by objects and events such as collisions, and sounds cause auditory experiences. However, sounds are not auditorily experienced to travel through the surrounding medium as waves do. Thus, if sounds are waves, then the sounds we hear may be proximal, located at the ear of the hearer.
On such an account, sounds commonly appear auditorily to be in the neighborhood of their sources and thereby furnish useful information about the locations of those sources. The sound of the drumming across the street seems to come from across the street but does not seem audibly to travel. When sounds do appear to fill a room, sound seems located all around. Sounds, according to this conception, ordinarily appear to have distal locations and to remain stationary relative to their sources.
If sounds are not usually experienced to travel, then unless auditory experience is illusory with respect to the apparent locations of sounds, sounds themselves do not travel. Sounds thus are not identical with and do not supervene locally upon the waves, since waves travel Pasnau On this view, pressure waves bear information about sounds and are the proximal causes of auditory experiences, but are not identical with sounds.
One might object by resisting the phenomenological claim that we experience sounds as distally located, for instance by suggesting that audition is aspatial, or that audition is spatial but sound sources rather than sounds are auditorily localized see section 3. Or, one might accept some measure of illusion. Another possibility is that we experience only a small subset of the locations sounds occupy during their lifetimes for instance, while at their sources , and simply fail to experience where they are at other times.
This avoids ascribing illusion. Finally, Fowler argues indirectly on the basis of echoes against distal theories of sound. Are sounds properties or individuals? Among both proximal and distal theories, disagreement exists concerning the ontological category to which sounds belong. Philosophers traditionally have understood sounds as properties—either as sensible or secondary qualities, or as the categorical or physical properties that ground powers to affect subjects.
Commonly, sounds are attributed to the medium that intervenes between sources and perceivers. More recently, however, some distal theorists have argued that sounds are properties of what we ordinarily understand as sound sources—bells and whistles have or possess rather than make or produce sounds.
Pasnau , for instance, claims that sounds are transient properties that are identical with or supervene upon vibrations of objects. This account implies that sounds sometimes make sounds they do not have, and that they have sounds when silent. One also might ask whether events such as collisions and strummings, rather than objects, bear sounds. Leddington recently has defended such an account. A revisionist challenge comes from those who argue that sounds are individuals rather than properties.
Several arguments support this understanding. First, empirical work on auditory scene analysis suggests that one primary task of audition is to carve up the acoustic scene into distinct sounds, each of which may possess its own pitch, timbre, and loudness Bregman Multiple distinct sounds with different audible attributes can be heard simultaneously.
Such bundling or grouping of audible features suggests that sounds are perceptible individuals to which these features are attributed. Furthermore, the temporal characteristics of experienced sounds suggest that sounds are not simple qualities. Sounds audibly seem to persist through time and to survive change. A particular sound, such as that of an emergency siren, might begin high-pitched and loud and end low-pitched and soft.
This suggests that sounds are individuals that bear different features at different times, rather than sensible qualities. Several responses to these arguments are available see Cohen for the most developed reply. One might argue that sounds are complex properties, such as pitch-timbre-loudness complexes, instantiated at a time.
To account for feature binding, one might hold that such complex properties are ascribed to ordinary objects such as bells and whistles. Or, one might hold that they are particularized properties, such as tropes.
To accommodate sounds that survive change through time, a property account could hold that sounds are yet more complex properties that have patterns of change built into their identity conditions. However, any such view differs a great deal from the familiar secondary or sensible quality view pioneered by Locke. Pitch, timbre, and loudness are better candidates for simple sensible features in audition see section 3.
If sounds are individuals, are they object-like or event-like individuals? Intuitively, the material objects we see are capable of existing wholly at any given moment, and all that is required to perceptually recognize such individuals is present at a moment. On the other hand, event-like individuals occupy time and need not exist wholly at any given moment. Their individuation and recognition frequently appeal to patterns of features over time.
Event-like individuals intuitively comprise temporal parts, while object-like individuals intuitively do not. The issue here is not the truth of endurantism or perdurantism as an account of the persistence of objects or events.
Instead, the issue concerns a difference in how we perceptually individuate, experience, and recognize individuals. No contemporary philosopher has yet claimed that sounds are objects in the ordinary sense. Those who argue that sounds are individuals commonly point out that sounds not only persist and survive change as do ordinary material objects , but also require time to occur or unfold. It is difficult to imagine an instantaneous sound, or one that lacks duration.
Sounds are not commonly treated as existing wholly at a given moment during their duration. Indeed, the identities of many common sounds are tied to patterns of change in qualities through time.
The sound of an ambulance siren differs from that of a police siren precisely because the two differ in patterns of qualitative change through time. This may bear on debates about persistence in the following way. Differences in the intuitive plausibility of endurantism and perdurantism may be grounded in facts about perception. In particular, vision may treat objects as persisting by enduring or being wholly present at each time at which they exist, while audition may treat its objects as persisting by perduring or having temporal parts.
This may stem from differences in perceptual organization. For instance, exhibiting a visible property profile at a time may suffice for being a visual object of a given sort, while being an audible object of a given sort may require exhibiting an audible property profile over time.
Though most philosophers construe sounds either as properties or as event-like individuals see section 2. The intended analogy is with visual objects. Talk of auditory objects gestures at the visual processes involved in perceptually discriminating, attentively tracking, recognizing and categorizing ordinary material objects. What justifies talk of object perception in audition?
First of all, humans typically do not auditorily perceive three-dimensional, bounded material objects as such , though it is plausible to think we visually perceive them. Hearing does not resolve the edges, boundaries, and filled volumes in space that I see, and I do not hear audible items to complete spatially behind occluders as do visible surfaces of objects. If perceiving a three-dimensional object requires awareness of its edges, boundaries, and extension, perhaps in order to discriminate it from its surroundings, humans typically do not auditorily perceive such objects.
Nevertheless, striking and illuminating parallels do exist between the perceptual processes and experiences that take place in vision and audition. Perceiving objects requires parsing a perceptual scene into distinct units that one can attend to and distinguish from each other and from a background. In vision, bounded, cohesive collections of surfaces that are extended in space and that persist through time play this role see, e. In audition, as in vision, multiple distinct perceptible individuals might exist simultaneously, and each might persist and survive change see the discussion of auditory scene analysis in section 2.
For instance, audible individuals have temporal edges and boundaries, and boundary elements can belong only to a single audible individual. They also are susceptible to figure-ground effects over time. One can, for instance, shift attention among continuous audible individuals that differ in pitch. Furthermore, they are susceptible to completion effects over time in much the same way that visible objects are perceptually completed in space.
Seeing a single visible region to continue behind a barrier is analogous to hearing a sound stream to continue through masking noise, which may take place even when there is no corresponding signal Bregman , Finally, multiple distinct, discrete audible individuals, such as the temporally bounded notes in a tune, can form audible streams that comprise a single perceptible unit. Though such complex audible individuals include sounds, they comprise temporally unified collections of sounds and silence that are analogous to spatially complex visible objects, such as tractors.
Such audible individuals are temporally extended and bounded, serve as the locus for auditory attention, prompt completion effects, and are subject to figure-ground distinctions in pitch space. For these reasons, the auditory processes involved in their perception parallel those involved in the visual perception of ordinary three-dimensional objects. The parallels suggest a shared sense in which vision and audition involve a more general form of object perception see, e.
Kubovy and Van Valkenburg , define objecthood in terms of figure-ground segregation, which requires perceptual grouping. They propose the theory of indispensable attributes as an account of the necessary conditions on perceptual grouping see also Kubovy Indispensable attributes for a modality are those without which perceptual numerosity is impossible.
They claim that while space and time are indispensable attributes for vision and color is not , pitch and time are indispensable attributes for auditory objects. Discussion of auditory objects thus draws attention to two roles that space plays in vision. First, there is the role of space in determining the structure internal to visible objects, which facilitates identifying and recognizing visible objects.
Second, space serves as the external structure among visible objects, and is critical in distinguishing objects from each other. In audition, time plays a role similar to space in vision in determining the structure internal to auditory objects.
Pitch, on the other hand, serves as an external structural framework, along with space, that helps to distinguish among audible individuals. Why is it useful to perceive such individuals in audition? One promising account is that they provide useful information about the happenings that produce sounds. Carving the acoustic world into mereologically complex individuals informs us about what is going on in the extra-acoustic environment. It provides ecologically significant information about what the furniture is doing, rather than just how it is arranged.
It is one thing to perceive a tree; it is another to hear that it is falling behind you. Discussion of auditory objects and accounts of their nature and perception is relatively new among philosophers see, e. Such work has led to the development of general accounts of perceptual objects designed to avoid visuocentrism see, e.
This area is ripe for philosophical contributions. Sounds are among the objects of audition. Plausibly, so are complex, temporally extended individuals composed of sounds. Do we hear anything else? Reflection suggests we hear things beyond sounds and sound complexes. In hearing sounds, one may seem to experience the backfiring of the car or the banging of the drum.
If sounds were internal sensations or sense-data, then, as Maclachlan observes, we would hear sound sources only indirectly, in an epistemological sense, perhaps thanks to something akin to inference. Acquiring beliefs about the environment would require mediation by propositions connecting experienced internal sounds with environmental causes. If, however, sounds are properties attributed either to ordinary objects, as Pasnau and Kulvicki hold, or to events, as Leddington holds, then hearing a tuba or the playing of a tuba might only require hearing its sounds.
Perceptually ascribing such audible attributes to their sources might ground epistemically unmediated awareness of tubas or their playings. However, the individuals to which audible attributes are perceptually attributed need not be identical with ordinary objects or events.
Instead, audible attributes may belong in the first instance to sounds. Suppose then that one could not hear an ordinary object or event without there existing an audible sound, as well as that sounds can mislead about their sources it might sound like drumming but be hammering. Given this, forming beliefs about ordinary things and happenings connected with sounds might seem to require inference, association, or some otherwise cognitive process, and so awareness of a sound source might appear to always involve more than perceptual awareness.
According to such an account, awareness of environmental things and happenings thanks to audition is epistemically mediated by awareness as of sounds and auditory objects, but does not itself constitute auditory perceptual awareness as of those things and happenings. You are inclined to think you hear the source because your representing or being aware of it co-occurs with, but is no more than a downstream consequence triggered by, your auditory experience.
Such an account is not wholly satisfactory. First, the phenomenology of audition suggests something stronger than indirect, epistemically mediated awareness of things such as collisions or guitar strummings or lions roaring.
Reflection suggests auditory awareness as of collisions, strummings, and lions. Second, the capacity to refer demonstratively to such things and events on auditory grounds also suggests genuine perceptual awareness of them. Third, we commonly perceptually individuate sounds in terms of their apparent sources, and our taxonomy reflects this. Furthermore, characterizing certain audible features and explaining perceptual constancy effects involving such features requires appeal to sound sources.
Explaining loudness constancy—why moving to the back of the room does not change how loudly the lecturer seems to speak—appeals to facts about the sources of sounds Zahorik and Wightman Auditory processing proceeds in accordance with natural constraints concerning characteristics of sound sources, and information concerning sources shapes how auditory experiences are organized.
This is to say that processes responsible for auditory experience proceed as if acoustic information is information about sound sources. Finally, audition-guided action supports the claim that we hear such things and events. Turning to look toward the source of a sound or ducking out of the way of something we hear to be approaching—behaviors guided by auditory experience—would make little sense if we heard only sounds.
In the first place, these reasons ground a case for thinking that auditory perceptual experience does not strictly end with sounds and auditory objects. The main barrier to an alternative is that the relation between sounds and ordinary things or happenings is commonly understood as causal see, e. Awareness as of an effect does not itself typically furnish epistemically unmediated awareness of its cause.
Seeing smoke is not seeing fire. The right sort of dependence between characteristics of the experience and the cause is not apparent, and awareness as of an effect does not by itself ground perceptual demonstratives that concern the cause.
Is there another explanatory route? Parthood frequently does ground perceptual awareness. For instance, seeing distinct parts of a surface interrupted by an occluder leads to perceptual experience as of a single surface imagine seeing a dog behind a picket fence.
Seeing the facing surfaces of a cube affords awareness as of a cube, and we can attentively track that same cube as it rotates and reveals different surfaces. Suppose, then, that a sound is an event-like individual recall, property accounts escape the worry. This event is part of a more encompassing event, such as a collision or the playing of a trumpet, that occurs in the environment and that includes the sound. So, the typical horse race includes the sounds, and you might auditorily perceive the racing in hearing some of its proper parts: the sounds.
More specifically, you may hear the galloping thanks to hearing the sounds it includes. The sound is not identical with the galloping, and it is not just a property or a causal byproduct of the galloping.
It is a part of a particular event of galloping. The metaphysical relation of part to whole, in contrast to that between effect and cause, might ground the sort of epistemically unmediated awareness of interest cf. Nakayama et al.
Auditory perceptual awareness as of the whole may occur thanks to experiencing the part. One objection is that this mereological account of the relation between sounds and sources cannot account for hearing ordinary objects by hearing their sounds.
You could not strictly hear a tuba by hearing its sound because a tuba is not an event of which a sound is a part. However, the sound is part of the event of playing the tuba, and the tuba is a participant in that playing.
So, though you are not aware as of a tuba, you are aware as of an event that involves a tuba. That perhaps is enough to explain talk of hearing tubas and to assuage the worry for further discussion, see Young 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. In either case, it seems reasonable that token events that do not include sounds are inaudible. Casati et al. The sound just is the collision or the vibrating, whether or not it occurs in air. This account implies that sounds could exist in vacuums. What hinges on the debate about hearing sources? The first upshot is epistemological and concerns the nature of the justification for empirical beliefs grounded in perceptual experience.
The evidential status of beliefs about what one perceptually experiences differs from that of beliefs about what is causally responsible for what one perceptually experiences. So, whether or not we hear sound sources impacts the epistemology of audition. The second upshot concerns the relation between audition and certain actions.
If we hear only sounds and auditory objects, what appears to be effortless, auditorily guided action to avoid or orient toward sound sources requires another explanation because sounds are invisible and usually do no harm. Finally, it affects how we understand the adaptive significance of audition.
Did audition evolve so as to furnish awareness of sounds alone, while leaving their environmental significance to extra-perceptual cognition, or did it evolve so as to furnish perceptual responsiveness to the sources of sounds? Two topics are especially noteworthy in the context of related debates about vision and its contents.
The first concerns the whether audition has spatial content. The second concerns the perception of audible qualities. Parallel questions can be raised without relying on the perceptual content framework, though important complications arise. One topic where the contrast between vision and audition has been thought to be particularly philosophically significant concerns space.
Vision is a robustly spatial perceptual modality. Vision furnishes awareness of space and spatial features. Hearing also provides information about space—humans learn about space on the basis of hearing.
If audition represents space or spatial features, there is a natural account of being so informed. We might form beliefs about spatial features of environments on the basis of auditory perceptual experiences simply by accepting or endorsing what is apparent in having those experiences. For instance, volume might bear information about distance, and differences in volume at the two ears might bear information about direction.
In that case, audition bears information about space, and learning about space on the basis of audition is possible, but it does not follow that auditory experience is spatial or that audition represents space. Certainly, our capacity to glean information about space is less acute in audition than in vision.
Vision reveals fine-grained spatial details that audition cannot convey, such as patterns and textures. But philosophers who are skeptical about spatial audition are not just concerned about a difference in spatial acuity between audition and vision. The claim is that, in contrast to visible objects, audible sounds are not experienced as having locations.
Rather, we determine the places of sounds and sources from acoustic features, such as loudness and interaural differences, that bear information about distance and direction. We do not auditorily experience spatial features. This debate, and the purported contrast between vision and audition, has consequences for perceptual theorizing.
One route to the conclusion that hearing sounds involves auditory awareness of sensations involves denying that audition satisfies spatial prerequisites on experiencing sounds as objective or public. Maclachlan means that, in contrast even to the case of pains, which are felt at different bodily locations, sounds are not experienced to be at differing locations, and so we are not even inclined to recognize that they are bodily sensations.
Maclachlan then suggests that we associate sounds with things and happenings outside the body rather than appreciate that they are effects in us. Given the lack of spatial variation among experienced sounds, we projectively associate sounds with distal sources. This explanation assumes that experienced sounds exhibit no audibly apparent spatial variation: sounds seem located at the ears or lack apparent location altogether. Denying that auditory experiences present sounds at varying locations beyond the ears invites difficulty in finding a place for sounds in the world.
If audition is wholly aspatial, this may encourage a retreat to the view that sounds lack locations outside the mind. This kind of strategy has companions and precursors. Each recalls the Kantian claim that objectivity requires space, or that grasping something as independent from oneself requires the experience of space, a version of which is deployed by Strawson , ch 2 in his famous discussion of sounds.
Two lines of response are open. Scientists aim to discover the cues and perceptual mechanisms that ground spatial audition, such as interaural time and level differences, secondary and reverberant signals, and head-related transfer functions.
Nevertheless, this research strongly supports the claim that human subjects auditorily perceive such spatial characteristics as direction and distance. Second, a number of philosophers have objected on phenomenological grounds. Introspection and performance support the claim that sounds or sound sources are in many ordinary cases perceptually experienced as located in the environment at a distance in some direction.
Though hearing is more error prone than vision, we frequently do not need to work out the locations of sounds or sources—we simply hear them.
A subtler form of skepticism about spatial audition aims just to block the requirements on objectivity. Strawson famously argues in Chapter 2 of Individuals that because auditory experience is not intrinsically spatial—spatial concepts have no intrinsic auditory significance—a purely auditory experience would be non-spatial. Thus, it would not satisfy the requirements on non-solipsistic consciousness.
The claim that audition is not intrinsically spatial admits at least two readings. First, since Strawson suggests that audition might inherit spatial content from other sense modalities, such as vision or touch, it could mean that audition depends for its spatial content upon that of other modalities.
Second, it might be understood as a claim about the objects of audition. Strawson indicates that sounds themselves are not intrinsically spatial.
Since these interpretations are not clearly distinguished by Strawson, it is helpful to consider his master argument. Strawson claims that a purely auditory experience would be non-spatial.
However, if any modality in isolation ever could ground spatial experience, audition could. On one hand, given the mechanisms of spatial hearing, it is empirically implausible that a normal acoustic environment with rich spatial cues would fail to produce even a minimally spatial purely auditory experience.
Even listening only to stereo headphones could produce a directional auditory experience. On the other hand, it does seem possible that there could be a non-spatial but impoverished exclusively auditory experience if no binaural or other spatial cues were present.
But similarly impoverished, non-spatial experiences seem possible for other modalities. Consider visually experiencing a uniform gray ganzfeld, or floating weightlessly in a uniformly warm bath. Neither provides the materials for spatial concepts, so neither differs from audition in this respect. Nudds suggests another way to understand the claim, and interprets Strawson as making an observation about the internal structure of audition:.
Audition, unlike vision, lacks a spatial structure or field, claims Nudds. A purely auditory experience thus would not comprise a spatial field into which individuals independent from oneself might figure. Following an example from Martin , Nudds argues that while vision involves awareness of unoccupied locations, audition does not involve awareness of regions of space as empty or unoccupied.
In audition, Nudds claims, one never experiences a space as empty or unoccupied. In response, one might simply deny a difference between vision and audition in this respect. If one can attend to a location near the center of the visible ring as empty, one can attend to the location between the sounding alarm clock and the slamming door as a place where there is no audible sound—as acoustically empty space.
Of course, auditory space generally is less replete than visual space, but this is contingent. Consider seeing just a few stars flickering on and off against a dark sky.
Since such an experience may have spatial structure, and since it is analogous to audition, one might on these grounds defend the claim that audition has spatial structure see also Young But without further argument, or a commitment to a theory of sounds, it is difficult to state confidently the intrinsic features of sounds and thus whether they include spatial features.
Nonetheless, the claim might be that, as they are perceptually experienced to be, sounds lack apparent intrinsic or non-relational spatial features. Roughly, independent from spatial relations to other sounds, experienced sounds seem to lack internal spatial structure. That is why you cannot auditorily experience the empty space at the center of a sound or hear its edges.
Interpreted as such—that sounds are not experienced or perceptually represented to have inherent spatial features—the claim is plausible though consider diffuse or spread out sounds in contrast to focused or pinpoint sounds. It certainly marks an important difference from vision, whose objects frequently not only seem to have rich internal spatial structure, but also are individuated in terms of inherent spatial features.
Since sounds phenomenologically seem to be located in space and to bear extrinsic spatial relations to each other, auditory experience satisfies the requirements for objectivity, which need only secure the materials for a conception of a place for sounds to exist when not experienced. So, vision and audition differ with respect to space in two ways. However, given the spatial characteristics evident in audition, such as direction and distance, the spatial status of audition presents no barrier to understanding its objects as perceiver-independent.
If that is the case, then audition provides no special intuitive support for accounts on which private entities are the direct objects of perception. According to theories in which sounds are individuals, sounds are not secondary or sensible qualities.
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