Learn about how some sounds are high, and others low.
What is Pitch?
The relative height of a sound, ranging from low to high.
A few pitches
Here are a few different pitches. Each of these are at a different height.
The three pitches in this soundfile above might be described respectively as:
Beyond Traditional Ideas of Pitch
In traditional musical notation pitch is indicated along the vertical axis of the stave. The pitches of sounds can be quickly described as being low, middle or high pitched. But we can split this into as many registers as are required (e.g. Low-Medium, High-Medium etc.).
This is a pitched sound. A sine tone is the most simple pitched sound.
You can see the simplicity and the focus of this sound energy by looking at a Spectrogram of the sound.
Of course, not every sound has a clear pitch. Many noisy textures are spread across the pitch register and do not have a specific main focus.
A noisy sound which has no clear pitch.
Pitch can also be described in terms of frequency.
Frequency is a scientific term that describes pitch (just as H2O is a scientific term that describes water).
A high frequency sound has a high pitch, while a low frequency sound has a low pitch.
Some sound sources produce more than one pitch, either at the same time.
Either at the same time
North American Train Horn
This single horn sound contains multiple pitches playing at the same time.
Or one after the other:
This birdsong is a short melody of different notes following on from one another. Because the notes happen in quick succession we hear this as a single gesture.
When we examine individual sounds in detail we can discover that sounds are often made up of individual pitch elements. For more information see: Complex Sound waves.
This is a Spectrogram of a Triangle wave. A single triangle wave is itself made up of many individual pitches, we see them here as stripes.
What Causes Pitch?
Pitched sounds are caused by regular vibrations. If an object vibrates in a regular way (moving back and forth smoothly) then it will create a pitched sound. The less regular the sound vibrates then the noisier it is.
We can experience this by rubbing our finger around the damp rim of a glass to make it sing.
•Ask someone at home if you can borrow a wine glass (or any glass with a stem).
•Pick a wine glass that makes a good ring when you tap it.
•Wet your finger and the rim of the glass.
•Then, while holding the glass firmly with your non-writing hand, take the first finger of your writing hand and rub it smoothly and steadily around the rim of the glass.
•If you are able to make smooth and steady regular motions around the rim the glass should begin to sing, creating a pitched note.
•If you move your writing hand in an irregular way around the glass then no pitch will be created.
Why is a pitch created?
The smooth and steady motion of the hand around the rim of the glass causes the glass to vibrate in a regular way, and thus to produce a pitched sound.
By changing the level of liquid in the glass it is possible to change the pitch.
This is because the liquid dampens the vibrations where it touches the glass, thus changing the amount of the glass which is free to vibrate.
The more liquid in the glass, the smaller the surface that can vibrate and the higher the pitch produced.
This process is similar to the way in which changing the length of a string on a guitar of violin will change the pitch made (shorter string = higher pitch).
Changing the Pitch
Using technology it is possible for us to change the pitch of sounds.
The process is known as Pitch-Shifting or Transposition. This technique is often used in pop music or cartoons to create high pitched voices.
This is the original unedited recording.
This is the pitch-shifted version in which the sound has been increased in pitch.
This can be a really useful effect to transform and develop sounds. For example see: Transformations, for an example of the use of pitch shifting in creating transformations.
Try to use a mixture of high, medium and low pitched sounds in your compositions.
Using a range of different pitches allows you to fill up the whole sound range and provide a much richer soundscape.
Changing Pitch over Time
Using Automation it is possible to transform the pitch shift of a sound over time. This can allow you to create glissandi and dynamic/changing transformations.
Pitch Shifted Clock
The amount of pitch shift increases over time
Find out more about how the Pitch shifting functionality works within Compose With Sounds.
Listen out for pitched sounds around you.
•How would you describe their pitch?
•Are they high/low,
•or are there multiple pitches?
Pitch as Property
The relative height of a sound, ranging from low to high. A pitched sound will contain relatively focused spectral energy, and it is this characteristic that enables pitched sounds to be distinguished from noisy sounds (see Noise).
Click Here to explore the properties of Pitch in more detail.
Pitch as Sound Type
Objects that vibrate in a more ordered fashion produce sounds that we describe as pitched. This is because the sounds produced contain a greater focus of sound wave energy, with frequencies concentrated into narrow bands. These concentrations of sound wave energy at certain frequencies are called partials.
术语顾问/Consultant to terminology