Musical Sounds

To understand what musical sounds are, we must first understand what sound is. Sound can be defined from two perspectives: one regards our perception through the auditory organ (the ear), and the other regards sound as a physical phenomenon. From a perceptual standpoint, sound is everything we can hear: the singing of birds, the noise of cars, the nervous beats in the radiator from the neighbor downstairs, or the voice of our mother calling us to the table to eat that wonderful broccoli, which has absolutely no taste.

From a physical perspective, sound is the vibration of elastic bodies that generate acoustic waves propagated through various materials such as air, water, or metal. However, at a perceptual level, we cannot perceive all vibrations; we only perceive those with a certain frequency (rate of vibration). Frequency is measured in hertz (Hz) and represents the number of vibrations per second. The human ear perceives sounds with frequencies between 20 Hz and 20 kHz, but this perception varies from species to species. For example, cats can hear sounds within the range from 45 Hz to 64 kHz, hedgehogs within the range from 250 Hz to 45 kHz, and if we ever want to compose music for mice, we will have to generate very high-pitched sounds because they can only hear within the range from 1000 Hz to 91 kHz.

Musical sound is a special type of sound that maintains its frequency constant long enough for it to be identified and eventually reproduced (by voice or musical instrument). From this perspective, we can divide sounds into musical sounds and noises. The difference is quite clear at the auditory level.

This is a musical sound – “C” (with a frequency of 261.64 Hz):

In principle, any human being can vocally reproduce this sound, regardless of musical talent.

On the other hand, this is a chainsaw noise:

If you managed to reproduce this noise vocally, I owe you my sincere congratulations.

Qualities of Musical Sounds

Now that we have defined what musical sounds are, let’s discuss its qualities, which are four: pitch, duration, intensity, and timbre. It is important to understand these qualities because music is nothing more than a continuous variation over time of the qualities of musical sounds.

Pitch

We have already discussed that the human ear can only perceive sounds within a certain frequency range. The way we perceive the frequency of a sound at the auditory level is what allows us to classify musical sounds as higher or lower.

In the audio clip below, there are several musical sounds produced by the same instrument that start out as low in pitch and then become increasingly higher.

 

Duration

Every musical sound has a certain duration in time, measured between the moment we start hearing the sound and the moment we no longer perceive it. Time can be measured as absolute time (in seconds or milliseconds). More importantly, time can be measured in a musical sense. A certain duration is taken as a reference, and the others are constructed by multiplying or dividing this duration.

In the following example, we have the same sound with decreasing durations (halving). Initially, the reference sound has a duration of “x,” followed by a sound that is four times longer (4x), then a sound that is twice as long (2x), the reference sound (x) again, and after that a sound that is half as short (x/2) and one that is a quarter as short (x/4).

The duration of a musical sound is also influenced by the type of musical instrument. There are instruments that can generate a continuous sound for an indefinite period (e.g., the violin or the organ) and instruments that cannot produce such a sound (e.g., the guitar or the piano). The human voice belongs to the latter category because we need to breathe from time to time.

Intensity

There are sounds that are louder or softer, and these differences define the intensity of the sound. There is a direct connection between intensity and what a musical passage aims to convey. For example, a lullaby sung by a mother will never sound as loud as a heavy metal band’s song.

In the example below, there is the musical sound “A” (with a frequency of 440 Hz) at various intensity levels:

Timbre

The timbre is perhaps the most fascinating quality of musical sound. A sound generated by any musical instrument contains not only the frequency that determines the pitch of the sound (which is called the fundamental), but also other frequencies called harmonics. These harmonics vary in intensity from one musical instrument to another, allowing us to distinguish, for example, the sound of a violin from the on of a trumpet, even though they produce sounds with the same pitch. That is why two voices cannot be exactly the same, foremost they are similar. In the matter of producing a musical timbre, the characteristic noise of each instrument also comes into play, noise occurring when we generate the sound (e.g., bowing the violin strings or plucking the strings of a guitar). Furthermore, the harmonics vary throughout the production of the sound, as well as depending on pitch and intensity. Ultimately, a unique sound is created, giving each musical instrument its own personality.

In the audio clip below, there is the sound “C” (261.64 Hz) electronically generated without harmonics, and then the same sound produced by seven other musical instruments.

The timbral characteristics of musical instruments are crucial when a composer wants to bring the musical idea to life. And some instruments even define a musical genre, a specific era or culture. In the video below there is a short scene from the movie ” The Forest Woman” (Pădureanca in Romanian) where the beloved actor Șerban Ionescu (in the role of Șofron) plays the jaw harp (drâmbă).