If a Tree Falls in the Forest

In my classes we recently discussed the question of what we mean when we say that something is real? One aspect of our experience we specifically addressed were sensory phenomena like color, fragrance, taste, and sound.

Students often hold the view that these phenomena are objectively real, that sugar is sweet regardless of whether anyone ever tastes sugar, the sky would be blue even if there were never any living things on earth to see it, and so on.

After we had moved on to other topics I came across an article that describes how music is transferred to a computer and then to the listener's ear. The description illustrates the point that a piano, for example, doesn't actually make music. The music is made in our brains. If there's no ear to hear it, no brain to interpret what the ear hears, there simply is no music.

Here's the article's description of the process of recording music for storage on a computer:

• The acoustic waves were picked up by a microphone and converted to electrical pulses.
• The pulses were converted by an analogue-to-digital (A-to-D) converter into numbers representing the frequencies and dynamics of the waveforms.
• The digital signals were compressed by an algorithm into a coded representation storable on an external medium, such as an MP3 file.
• The code was written as magnetic spots on a hard drive according to a storage algorithm that does not necessarily store them in physical order.
• On demand, a read head on the drive reconstructed the bits in their proper sequence and transmitted them as electrical pulses to the central processor.
• The CPU relayed the file to a router, where the file was packetized and sent over the internet to a specified address, possibly traversing electrical wires, the air (radio transmissions), or space via an orbiting satellite along the way.
• The destination site’s router reassembled the packets into a file for storage on a “cloud” server such as YouTube or SoundCloud.
• The website embedded the file’s location in its local server, which you, the listener, accessed by means of touch, using a mouse, keypad, or touchscreen.
• Your computer’s sound card converted the digital signals into audio output through speakers.

Notice that at no point in this process is there the sensation of sound. Nothing is actually heard. The article's description stops here, but if we were to continue the bullet points we could say that,

• The audio output of the speakers consists of waves of energy travelling through the air like waves in a slinky.
• When these strike an ear they're transformed into an electrical impulse that travels along the auditory nerve.
• When that impulse reaches the brain it's converted, in some mysterious, marvelous way that no one understands into the sensation of music.

Until that final event happens there is no music, no sound at all. The music is created by our brain and the relevant sensory apparatus. Sound is a sensation that we experience and without the involvement of a sense there can be no sensation. To insist that sound exists even though no one hears it is like insisting that pain exists even though no one feels it.

And if that's true of sound and pain it must be true of all of our other sensory experiences as well.

And if that's true what would the world be like if we had additional senses, or fewer senses? Why think that the world is exactly the way we perceive it to be, or, for that matter, anything at all like we perceive it to be?

Just something to think about over the weekend.