SOUND is a variation in the air pressure around us. This variation occurs from the vibration in material object, like a table knock or a car engine. The vibrating object is moving through a back and forth motion which produces the the variation in air pressure that becomes the sound in our ears, if it falls within our hearing range.

Wave – the shape of a sound, it’s unique character and tone.

Frequency – the pitch of a sound, it’s the frequency of the air pressure variations. It creates our perception of the pitch of the sound.

The more CPS – the higher the pitch we hear.

Each time the frequency doubles – the pitch rises by 1 octave.

Amplitude – the intensity of a sound, its loudness. It’s measured in decibels – logarithmic units used to describe a ratio of sound pressure. It has not linear relation to how we perceive the loudness.

Answers to discussion questions:

1. Name and describe five types of production tasks that ProTools can be used for.

-Pro Tools can be used for :audio and MIDI recording, composition, editing, mixing. It also provides the support for the desktop video.

2. What’s the frequency range of human hearing? 

-Frequency range of human hearing differs between 20Hz and 20kHz (also CPS – cycles per second).

3. What does the frequency of a sound wave affect in terms of how we perceive the sound? How is frequency measured? 

-Frequency affects the pitch of the sound.

4. What does the amplitude of the sound wave affect? How is amplitude measured? 

-Amplitude affects the intensity of the sound we hear, it’s loudness. It is measured in decibels.

5. How does the sample rate of a system relate to the frequency of audio it can capture? What is the name of the law that specifies the relationship between sample rate and audio frequency? 

-Sampling is the process of taking measurements of an electrical signal at various moments in time. The sample rate is the frequency with which these digital measurements are taken. The Nyquist Theorem ( or Sampling Theorem) states that in order to produce an accurate representation of a given frequency of sound, each cycle of the sound’s vibration must be sampled a minimum of two times, which is at least 40 kHz (twice the top range of human hearing). If the sample rate is any lower, the system will read the incoming frequencies inaccurately and produce the wrong tones (alias tones).

6. How does the bit depth relate to the dynamic range of audio it can capture. How can you estimate the dynamic range of a system? 

-The number of bits used for each sample is called the bit depth (binary word length). The more binary letters, the more accuracy in each sample measurement. Therefore, larger binary words are able to quantify the variations in amplitudes of the sound with better precision.

To estimate the useful dynamic range of an Audio/Digital system, we multiply the size of binary word by 6.

7. What are some common digital connections available on Pro Tools audio interfaces? What type of connector jack does each use? 

-Digital connections include S/PDIF (Sony/Philips Digital Interface – standard), which uses RCA jacks (coaxial jacks), and AES/EBU (Audio Engineering Society/European Broadcast Union – professional), which uses XLR-type connectors.

8. Name some audio interfaces that are compatible with standard Pro Tools software. 

• any audio interface that includes a supported Core Audio (Mac) or ASIO-Audio Stream Input Output (Windows) driver is compatible with standard Pro Tools Software.
• Some examples: M-Audio M-Track, Focusrite Scarlett, Behringer UMC 22, Audient iD4 MKII USB and many more.

9. Name some Avid audio interfaces that are compatible with Pro Tools | Ultimate software. 

• Pro Tools | HD OMNI: HD OMNI
• Pro Tools | HD I/O: HD I/O
• Pro Tools | HD MADI:
• ProTools|MTRX
• ProTools|MTRX Studio