Bring Up Hearing—Where is this sound coming from

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The type of stimulus that first recruits my awareness in the morning is most probably auditory. The sound may be coming from outside, like bird songs, or it could be coming from indoors, like my scheduled alarms. It certainly sounds more pleasant to be awakened by the tweeting of the birds, but living in Montréal, hearing the rumblings of heavy machinery is definitely more likely, which is sincerely irritating. This observation raises a particular question about the pleasantness of sounds and its origin. To answer the how and where its pleasantness comes from, we must know the differences between music and noise. However, it may not be as straightforward a question as it may seem.

The nature of sound is quite interesting as it doesn’t have any material constituents. Nobody was ever able to grab sound, to see sound or to taste sound. We cannot do any of those because a sound is a product of vibrations that spread through the air (or water) as acoustic waves. Depending on the properties displayed by the acoustic waves, the sound can be perceived differently. On the one hand, we can interpret a sound to have different levels of loudness which is attributed, in most parts, to the amplitude of the waves. The greater the amplitude (the height from the resting point to the top of the wave), the louder we recognize the sound to be. On the other hand, a sound can also have a different pitch depending on the specific period, frequency and wavelength it displays.

Acoustic waves generally follow the pattern dictated by sinusoidal functions, which we probably all encountered at some point in High School. For acoustic waves, the amplitude -determined by the height between the maximum and the x-axis- is still conserved. We only need one tiny adjustment; the x-axis now becomes known as the resting point. A period becomes the time it takes for the sound to complete its cycle. The frequency becomes the number of cycles completed within a specific time, which we typically calculate in Hertz (Hz; cycle/second). The wavelength is then the amount of distance sound can travel per period. They (all three) remain closely related to one another; the frequency is inversely proportional to both the period and the wavelength.

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These properties mean that the longer the wavelength (smaller Hz) is, the lower the frequency becomes. And as for the pitch, the inverse is also true. Although, there exist limitations to this observation. Namely, the limit of our human ear. They only possess the ability to detect sound within the range of 64 Hz to 23 kHz. However, some animals can perceive sound in much greater ranges than we can. Dogs are one of these animals with a hearing capacity between 67 Hz to 45 kHz. Nevertheless, cats take the lead here with their remarkable hearing sensibility ranging from 45 Hz to 67 kHz. This characteristic may describe their incredible success at hunting little prey such as rodents, which can emit sound as high as 100 kHz.

Depending on what the sound passes through, the speed and its direction can and will vary. Water, being thicker than air, will most definitely slow down sounds and redirect at a much greater angle than what we can observe with air. This redirection is also called refraction, which is the same phenomenon that is responsible for the shift of the image when seeing an object immersed in water. If, for whatever reason, you absolutely have no idea of what I am referring to, try this: take a transparent glass of water and partly submerged an opaque object in it (could be anything). You can see that the object seems broken when it passes through water, and that is refraction.

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Even though there are many properties characterizing sound, the ear is principally reactive to one, frequency. Amplitude will only play a background role to infer loudness to the sound. Our ear, which is our hearing organ, seems particularly attuned to pitch and loudness. As sounds are created, through the contact of objects causing vibration, it produces the acoustic waves as mentioned earlier. Upon hitting the auricle, the sound will be amplified and modulated before reaching the eardrum. The vibration, amplification and modulation create a chain reaction in the middle ear, which activates the ossicles (Malleus, Incus, and Stapes). The ossicles will then transmit the sound wave to the cochlea in the inner ear. In the cochlea, we can find plenty of hearing nerves, which connect to the brain. Once at the brain, the signal becomes interpreted to allow identification, classification and interpretation of the sounds.

It is the brain that is responsible for determining the pleasant nature of the sound we hear. Some people are affected by a condition that renders them unable to enjoy or derive any pleasure from music. This condition is known as musical anhedonia. It is a neurological condition caused by reduced connectivity in subcortical regions related to reward. Although these people might not be able to enjoy music, they can most definitely identify it, unlike those suffering from music agnosia. Despite their ability to hear, the latter cannot even tell the difference between music and noise. Individuals typically acquire this condition following an injury to at least one of the temporal lobes or after a unilateral stroke. These two conditions splendidly reveal the importance of the brain’s interpretation role in the perception of music.

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There is one more aspect of sound that I haven’t introduced yet: timbre. This term is often replaced by “sound quality” as it refers to the nature and distinctiveness of a sound, in other words, the pattern of harmonics. For instance, a violin will never sound exactly like a piano, even though you decide to play the same note at the same loudness level. Now, despite having described all these aspects and properties of sound, we still fall short when it comes to explaining where the pleasantness of music originates. However, what we have discussed so far was more related to sound itself and not music. What makes music is its rhythm or tempo, which creates sound arrangements through time, that can either be pleasing or not. When considering music perception, rhythm and pitch are the most central aspects involved.

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Now that I have introduced rhythm, we can start approaching closer to an answer. There are many factors involved; familiarity, distortion and reverb. As a general rule, we prefer sounds and/or patterns of sound that we are more familiar with; the ones we heard before. Usually, music acquires its different alluring attributes over relatively long periods. Music is pretty conservative as a general rule. However, beyond familiarity, there are distortion and reverb, each responsible for some aspect of pleasantness. Distortion comes from making the tone of the sound imperfect by changing its original form. Reverb is pretty much like echo, but instead of having the sound coming back to you in two parts, it comes back to you almost immediately. Although, not fast enough for merging with the original sound. The result becomes a continuation of the sound. We can often witness reverb in churches or even (ahem!) the shower. Reverb partly explains why it’s so delightful to hear ourselves signing in the shower. Yet, I cannot say I do much of that; my showers are always too short for that. How about you?

I thank you infinitely for reading this post and if you would like to know more about the mysteries that surround us, please join my subscription list to keep up with my newest content. If you have any questions, please add them to the comment section and I’ll make sure to answer as soon as humanly possible.

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Bring Up Biophilia—What makes us particularly attracted to nature

No one can dismiss the amazing feeling we get after spending some time in nature. We instantly feel relaxed and reinvigorated. Some might attribute this effect to time spent far away from work, and even though they could be correct, it is not the whole picture. Biophilia is a relatively new concept that brought the public more awareness to the role nature plays. The term refers to our innate propensity to be in nature or to connect with it. Our love for nature is so strong that the mere presence of reminders can be sufficient to initiate a cascade of positive effects. All the reactions produced can lead to a lightened mood, better cognitive processes, including concentration and focus, and a sudden burst in motivation. Nature’s reminders, also called biophilic elements, can be either alive or inanimate, but living elements can instigate the most impressive outcomes. To embrace the spirit of biophilia, we can begin introducing plants at home or add nature soundtracks as background noise. The possibilities are endless.

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Bring Up Blood—How our oxygen gets carried throughout our body

Good evening my dearest followers,

Please, take a moment to enjoy this excerpt for my newest post (Bring Up Blood).

We could most certainly not live without blood. It is absolutely essential for the survival of our most distant limbs and organs. Even though almost all of our respiration is thanks to our respiratory organs, blood is critical to carry oxygen further. Yet, the blood is not only responsible for some part of respiration, but it is also in charge of transporting many nutrients and immune cells. We, imperatively, need to learn more about the different elements of blood to understand its importance and necessity. Four main elements are particularly important: red blood cells, white blood cells, platelets, and plasma. All of these components play a large part in our life. Red blood cells notably carry oxygen, and white blood cells are our primary immune defence against potential chemicals and pathogens. Platelets help the blood coagulate, and plasma is the liquid transporting most nutrients, hormones and cells our body needs.

If you like the excerpt, please click the link below to access the whole article.

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Bring Up Artificial Intelligence—What can it do for us, or more precisely what it can’t

We keep hearing on the news of the many achievements made by Artificial Intelligence. From winning at Chess to winning at Jeopardy! against its longest streak-winner, AIs seem to truly outdo themselves. However, nobody can agree if those machines truly hold something we can call Artificial Intelligence. They can’t do more than the task they were built for, and they can’t even understand the game. In other words, they seem to greatly lack intelligence. So, should we find another more fitting definition of intelligence, or should we abandon the quest for human-like intelligence altogether? Personally, I consider that each pursuit for anything close to an Ex-Machina to be a most ambitious quest. The human mind and behaviours are really complex, which even raises questions about true AI’s feasibility. But don’t get me wrong, current AIs are very important. They help us achieve better safety measures, automation and greater management.

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