Have you ever heard yourself speaking on a recording? If you have, you were probably extremely surprised by how you sounded – maybe you didn't recognize your own voice or thought that there had been an error in the recording. Nope! In fact, your recorded voice is the voice everyone around you hears all day, every day.
In order to understand why people cannot hear how they actually sound when speaking, you have to understand what sound is and how it is created. When sound is produced, it is actually particles colliding into each other in a chain reaction – like dominoes. These collisions create a sound wave that travels at 340 meters per second. For comparison, the average speed of a plane is 245 meters per second.
Now that you know how sound works and what it is, you need to comprehend how humans process sound to understand why people cannot hear what they really sound like. Essentially sound waves from the environment enter the outer ear and cause the eardrum to vibrate. These vibrations cause the cochlea, a structure filled with fluid, to ripple.
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| Anatomy of the Human Ear |
In the cochlea is the basilar membrane, which contains hair cells. These ripples cause the hair cells on the basilar membrane to move up and down. When the hair cells move in this pattern, organelles in hair cells called stereocilia bend, causing small channels in the hair cells to open. Through these channels, an electrical signal is created. The signal is passed along the vestibulocochlear cranial nerve through action potentials, which is the electrical signaling between neurons, to the brain. Once in the brain, nerve fibers carry the signal to the auditory cortex in the temporal lobe.
While the electrical signal is traveling along the nerve fibers to the auditory cortex, the brain begins to process the signal into a recognizable form. The first thing that the brain does is trigger a reflex. For example, if there was a loud collision, the reflux would be to look at where the collision came from.
After a reflex is triggered, the primary auditory pathway is triggered. This pathway brings the electrical signal to the auditory cortex. First stop of this pathway: the brain stem. The brain stem is the part of the brain that relays signals to regulate the heart rate, body temperature, and breathing among other involuntary functions. On the primary auditory pathway, the brain stem evaluates the duration, intensity, and frequency of the electrical signal. The brain stem also helps determine where the sound came from. Once the electrical signal passes through the brain stem, it arrives in the thalamus at the base of the cerebrum. The thalamus uses the electrical signal to prepare the body for a motor response by stimulating the body's sensory systems (vision, touch, etc). The thalamus connects to the auditory cortex. In the auditory cortex, the electrical signal continues to be recognized and memorized. By this point, the brain has processed the electrical signal and is able to create a response, whether it be vocal, physical, or involves another attribute.
Since you now know what sound is, how it is heard, and how the brain processes the sound to produce a response, you are able to understand the reason why can people not hear what they really sound like when speaking. When someone is speaking there are actually two different vibrations being processed by the cochlea at the same time. The first vibration is from the environment. This vibration is created by the speakers' ears picking up on the sound. The second vibration comes from the vocal cords vibrating. When someone speaks, their vocal cords vibrate. These vibrations are typically deeper and have a low frequency. The sound someone hears while speaking is a combination of their ears processing the sound waves they are spreading into the environment and their vocal cords vibrating. When listening to a recording of themselves, someone will only process the sound through their outer ear instead of processing the vibrations from their vocal cords too. This is why someone's voice sounds different to them when speaking than it does to other people because when someone is speaking, their cochlea is processing sound from both the vocal cords and the outer ear, while other people are only processing the sound detected by their outer ear.
But then why do you sound different to yourself when you have a cold? Great question! Essentially when you have a cold, the structures around the vocal cords become inflamed and thus swollen. This swelling causes the vocal cords to vibrate at a slower rate and at a lower pitch, resulting in your voice being lower than it usually is. When you hear yourself speak, the sound waves you are creating in the environment and the vibrations coming from your vocal cords are different than they normally are, making you sound different to yourself.
Super interesting topic!! I always wondered why I sounded different over the phone or in a recording. There are so many pathways and signals involved in sound. You explained them all really well.
ReplyDeleteDo the processes described in the blog post also explain why one's voice can get more raspy when they smoke? I would imagine to how one's voice changes when they get a cold
ReplyDeleteYes, they are similar. When someone smokes, the vocal cords become irritated, which can lead to inflammation in the vocal cords. This can cause someone's voice to become more raspy.
DeleteI never knew that we heard two different sets of vibrations while speaking! So interesting. You also explained the effect of particle position and movement on wavelength and amplitude very well. I actually understand how those values are determined now!
ReplyDeleteThis makes so much sense! I always hate how I sound on recording and it makes me cringe when I hear it.
ReplyDelete