What is sound?

If you’ve opened this article, you’re definitely someone with a real interest in audio, whether you’re an Audiophile or a sound engineer. I’m glad you wanted to get back to learning simple but important things like this. Because based on the nature of sound, new recording and mixing equipment, sound absorption and soundproofing methods have been developed. So I don’t need to say more about the importance of learning from the ground up, right?

Let’s take a simple example, when you play music at high volume on your home stereo. Notice or even touch the diaphragm. You will see the diaphragm vibrate. Vibrating the diaphragm will change the surrounding air pressure.

As the diaphragm pushes out, the surrounding air is compressed. When the diaphragm contracts, the surrounding air is stretched.

Our ear has an eardrum which is a very thin membrane. This thin film is very sensitive. It can sense very small changes in air pressure. As a result, when the diaphragm vibrates, causing the air pressure to change, the eardrum will vibrate according to that change. On the tympanic membrane there are receptor cells sensitive to different frequency groups.

The brain will receive and analyze the mechanical vibration of the eardrum, information from the receptor cells and create the illusion of sound in the head, so that we can “hear” what the speaker is playing.

Yes. We just discovered two interesting things.

• First: The brain is involved in the listening process. The brain is the central organ where many mental and physiological processes take place. Therefore, we can understand that there are two aspects that affect the way we hear sounds, namely: physical and psychological. Vibration, air pressure belongs to physics. The process of receiving and analyzing the vibrations of the eardrum and creating sounds in our heads is psychophysiological. That means your perception of sound will be affected when you are happy, sad, healthy or tired. Too dangerous!
• Second: Air participates in the transmission of sound to the ear. So whatever affects the air affects the sound. What affects the air? Temperature, humidity, number of furniture in the room, furniture surface, furniture material, room geometry…

Interesting question: So does the speaker make sound after all?

Depending on your field of study, if it’s physics, the answer is yes. As understood by physicists:

Sound are essentially vibrations that are transmitted as mechanical waves of pressure through air or water.

Therefore, we can understand that the speaker emits sound.

However, if you are a psychologist. The answer may be no. To them, sound is simply the result of the reception of these waves and the brain’s sensory process to create the illusion of sound. Think back to your dreams or when you think about a certain song or melody. At this point, even though you don’t have any speakers around, you still “hear” the full sound, don’t you? Therefore, the speaker does not produce sound? That’s brain!

Really interesting, isn’t it?