Australia Recording Connection

285.203.110Recording Connection Audio Institute - Learn One on One in a Real Recording Studio

Lesson 1 – Intro to Sound and Hearing

At the Recording Connection Audio Institute, you will take 20 lessons at a pace of one lesson per week, from our structured course curriculum.

You will learn one on one inside a real recording studio from a professional audio engineer or music producer.

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Lesson 1 Synposis - Intro to Sound and Hearing


All sound is generated by creating a vibration in some sort of medium, whether strings, wood, vocal chords, or an insect’s wings. Sound is disseminated through different media by causing the particles around it to vibrate in a similar manner (that is, when an object vibrates, it causes the molecules around it to vibrate). The strings on a cello vibrate at a certain frequency, thereby causing the instrument’s sound board to vibrate, which displaces the air molecules near the instrument, and so on until eventually, the air particles in our ears begin bumping into tiny hairs in our inner ear. These hairs send impulses to our brain, telling us we are hearing a particular tone—and we interpret the vibrations as sound.

Sound must always travel through a medium; this is why it can be more difficult to hear in the lower air pressure of an airplane cabin—there are fewer air molecules to act as a medium for the sound.


A waveform of a signal is a pictorial representation of the changes in the signal’s amplitude over a period of time. Imagine dropping a rock into a calm pond of water. If you took a picture of a cross-section of the water, that picture would be a graphic depiction of the amplitude of the water versus distance (one side of the picture would be closer to the rock’s ground-zero), which is easily be translated into time. This is a good example of a waveform.


Sound moves more quickly through some media than others, depending on how dense the medium happens to be. In water, for example, sound travels approximately four times faster in than it does in the in air, because the molecular structures and density of those two substances are different. Sound travels about ten times slower in rubber than in air. Another factor affecting the speed of sound is temperature. In air at 0°C at sea level, sound travels at a speed of 331 m/s. For each degree Celsius increase in temperature at that level, sound will travel about .60 m/s faster.


The pitch (or frequency) of a sound also affects the way we hear it. Our human ears are formed in such a way that we experience a natural difficulty in determining the source of a sound at a low frequency—yet we can accurately pinpoint the source of a sound at high frequency. This is an important factor to take into account when tuning and balancing a sound system.


Besides pitch, loudness is a property our human ears can also perceive, related to the intensity of the sound wave we are hearing. The intensity of a wave is essentially the amplitude of the wave; generally speaking, the higher the amplitude, the louder it sounds in our ears.

In the 1930s, two researchers named Fletcher and Munson discovered that the human ear’s natural frequency response also affects how loudly we hear certain sounds. Their studies reveal that the ear is most sensitive to sounds occurring between 3 kHz to 4 kHz in frequency. This means that frequencies higher than 4 kHz and below 3 kHz must be somewhat louder than frequencies within that range before our ears will perceive them as loud.


How do we perceive or determine the origin of sound? How do we know from which direction a train is approaching? Our two ears use what we call “binaural localization” to discern the source of a sound, basically using three factors:

  • Differences in inter-aural intensity
  • Differences in inter-aural arrive-time
  • Pinnae of the ears themselves

These, along with other characteristics of the human hearing system, are factors we must take into account in designing a sound system that sounds natural to our ears. We will study these characteristics in detail.

Supplemental Videos for Lesson 1

Lesson 1A

Lesson 1B

Studio Tip 1A

Studio Tip 1B