Loudness (or Amplitude)

I am sure that you have complained about loud sounds at least once in your life. I have 3 sons so I think I might have done so, more times than an average person.

Loudness or Amplitude in layman's term would refer to volume. A higher amplitude indicates higher volume and a lower volume results to lower amplitude. When we look at sound waves, amplitude represents the spike from the equilibrium point. The higher wave height means that the sound is louder.

Let's take a look at an example. I recorded the sound of an Ehru in GarageBand. I used high and low volumes and used an Oscilloscope to review the wave strength. Notice the difference in wave height.

Pitch (or Frequency)

Pitch refers to the speed of vibration that results to a higher or lower frequency. It is represented by the number of wavelength in one second. The more waves per second indicate a higher frequency.

I recorded the sound of a Flute Organ in GarageBand using 2 different frequencies. As you can see below, the lower frequency, the less waves created over time. In 16ms, only 4 waves registered in low frequencies and 5 times more for high frequencies.

Duration

Duration is the property that is easy to measure. It refers to the time interval from the start until the end of the sound. Each vibration produces different sound duration. Some objects for example, produce longer sounds while others would be short and quick.

The sounds of objects depends on physical composition. The sound duration of a balloon made of rubber will be shorter compared to a bell made of metal. I recorded 2 types of sounds I found in the internet - a balloon pop and a bell ring. The pop is quick and lasts a sec (or less) while the bell ring is longer.

Articulation

This property of sound refers to the the attack, sustain, and decay of a sound. Attack is the sound intensity from the starting point before it reaches a steady state (sustain) and before it goes back to silence (decay).

Using GarageBand, I recorded the intensity of a piano key and how it moves from attack to decay.

Diffusion/Spatialization

Some resources define Diffusion and Spatialisation as Direction of Sound. This property of sound highlights the flow and intensity of sound based on the location of the source. The level of intensity allows us to perceive the sound direction by utilising the arrival time of the sound wave. Thus, we are able determine if the source is near or far.

Sound direction or how it is diffused is determined by many factors in the environment. This includes materials that may absorb sound or bounce it off. An example that you might have experienced in the past is the quality of sound in an unfurnished condo/room compared to a furnished one. In an unfurnished room, sound bounces off the walls causing an echo effect. But once the room has been furnished with a lot of sound absorbing materials, the "echo" sound is eliminated or reduced.

My sound clip for diffusion is the sound of EDSA traffic. I live in a condominium right next to EDSA. It is great because the location is very convenient but there is never a quiet moment. When listening to this clip, you'd notice that your attention will be drawn to the sound of a siren or alarm despite the sounds from other vehicles. It is a distinguishable sound and since we already know what it signifies, it raises our attention to selectively focus on that.

Timbre

Often coined as sound quality, this sound property takes into account the balance and harmony of different frequencies and amplitude.

To illustrate this, I played around with different instruments in GarageBand using a preset melody. Since the frequency has been preset, I just tweaked the amplitude to balance the sound of each instrument.

In the clip (Timbre1) below, I started with just one instrument - Rock Organ followed by the other instruments after 2 seconds. Notice the difference in sound quality as additional instruments with different frequencies and amplitude is added. Each instrument has different wave patterns even if the melody is the same (except for the drums). I included a full version with all the instruments playing from the start of the recording for comparison. As you can see, the wave pattern has also changed with all the instruments played together.

Sounds are amazing and without it, life as we know it will never be the same. Based on what I have learned about sound in this activity, it is indeed true that we can unlock the mysteries of the universe when we start listening...