A sound wave is an example of a longitudinal wave. This means that the medium oscillates parallel to the movement of the Energy.
In the case of sound, the medium is the material that the sound is travelling through, which in most examples will be either in air or water.
What is a Sound Wave ?
To create a sound wave, something must cause the medium around it to vibrate. This vibration causes the medium to be compressed (squeezed together) or rarefied (spread out), as can be seen in the diagram above.
Visualising a Sound Wave
As a sound wave is a longitudinal wave, it can be hard to describe based upon the terms used in the last section.
However, if the sound wave is recorded by an oscilloscope, the signal generated can be represented by a transverse signal.
The image below shows a sound wave as represented by an oscilloscope:-
Amplitude and Frequency, Pitch and Volume
In music, the concepts of pitch and volume are clear descriptions of sound.
Both of these can be described using the correct Physics terms:-
1. Volume - How loud or quiet a sound is . In Physics, Volume is defined as Amplitude.
2. Pitch- How high or low a Sound is . In Physics, Pitch is defined as Frequency.
Volume and the Decibel Scale
In Physics, the loudness of a sound is measured using the unit - Decibel (dB). The diagram below shows the Decibel scale, with some example sounds:-
Note - The Decibel scale is a logarithmic scale, not a linear scale. This means that an increase of 10 Decibels gives double the Volume.
Sound and the Range of Human Hearing
As explained earlier, in Physics the Frequency of a sound wave (or any wave) is measured in Hertz (Hz). Sound can be generated in a wide range of Frequencies, however, only certain Frequencies can be heard by humans.
Sound Frequencies that we can hear are known as the range of human hearing.
" The range of human hearing is 20 Hz - 20,000 Hz "
Sound below 20 Hz is known as Infrasound. Sound above 20,000 Hz is known as Ultrasound.
Sounds with a Frequency less than 20 Hz
Elephants use Infrasound to communicate over several miles, detecting the waves with their feet.
Infrasound has been shown to given people the sensation of unease or even fear.
Whales use Infrasound to communicate with each other over hundreds of miles.
Sounds with a Frequency greater than 20,000 Hz
Bats, Insects and Cetaceans (Whales and Dolphins) use Ultrasound to measure distances or detect prey.
Ultrasound can be used to image safely within the Human body, for example observing an unborn baby.
As you age, your ability to hear the high Frequency sounds is reduced. Young people can hear high Frequency notes that older people cannot.
Studio Sound Engineer
You would make high quality recordings of music, speech and sound effects.
You would; Plan recording sessions with producers and artists, Set up microphones and equipment in the studio, Make sure the recording levels are set correctly, Use recording equipment and add effects, Record each instrument or item onto a separate track, Mix tracks to produce a final version, Log tapes and other details of the session, With experience, you might also act as studio manager.
A Career as a Studio Sound Engineer
Salary: from £18,000 to £39,000 per year
Sound Engineer working hours: You would need to be flexible about your working hours, which could be long and irregular. You may need to work in the evening, at night or at the weekend. This could depend on when artists and producers are available.
Typical entry requirements: There are no set entry qualifications required to enter this job but qualifications and experience of sound technology and the music industry such as a Higher National Diploma in Sound Production (SCQF level 8) will be of value.
You can enter some Sound Production National Certificate or National Qualification courses (SCQF 2-6) with no formal qualifications but most courses ask for National 4/5 qualifications (SCQF level 4/5).
You can enter Higher National Certificate (SCQF level 7) or Higher National Diploma courses (SCQF level 8) with National 4/5 qualifications and one to two Highers or equivalent qualifications.
To enter a degree (SCQF level 9/10) in areas like sound production, music technology or audio engineering usually requires National 5 qualifications and a minimum of three Highers or a relevant HNC/HND.
Working with technology
Attention to detail
Developing a plan