sound, harmonics, frequency and pitch
Post on 24-May-2015
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Music Technology
Musical Acoustics
What is Sound?
What is Sound?
Human Aspect of Sound?
Physical Aspect of Sound?
What is Sound?
Human Aspect of Sound?What is heard
Physical Aspect of Sound?Pressure disturbances propagating through a medium, usually air
What is Pitch?
What is Pitch?
Repetition rate in a Sound
Not the same as frequency – a note with given pitch normally contain many frequencies – what are these different frequencies called?
What is Frequency?
Repetition rate for a simple oscillator
An oscillator is a repetitive wave e.g. sine wave, saw wave etc.
What is Frequency measured in?
What is Frequency measured in?
Hertz
Normal hearing range is 30-15,000Hz
Frequencies
The range of pitch of the piano is 30-4,000Hz
The lowest notes are heard almost entirely via the harmonics present in the tone.
Harmonics
All oscillations contain more than one frequency. The cluster of all the different sounding frequencies make the tone of the sound.
The frequencies are often exact multiples of the lowest, fundamental frequency, or near to this.
Harmonics
What, therefore, does EQ do?
What, therefore, does EQ do?
• Boosts and cuts certain frequencies, which will inevitably, take out or increase the dynamic volume of some of the harmonics.
EQ Bands
Normally three bands:
High Freq: 5-6kHz upwardsMid-Range: 500Hz – 5kHzLow Freq: 50Hz-500Hz
Why should you use EQ?
Why should you use EQ?
• Enhances the balance of the overall sound, by altering the tonal qualities of individual instruments
• Makes MIDI sounds more realistic• Removes unwanted frequencies• Separates mid-range sounds that are similar in
frequency, helps to give clarity to the mix, and stops them blending too much on important parts
• Bring out important melodies
Types of EQ
Shelving EQ
Types of EQ
Shelving EQ:
High freq: Cut/boost all the signal above a certain frequencyLow freq: Cut/boost all the signal below a certain freq.
Can you draw it?
High-Shelf Boost
Low Shelf and High Shelf Cut
Band Pass EQ
Cut/boost the signal between an upper and lower frequency.
Band Pass EQ
Cut/boost the signal between an upper and lower frequency.
Sweep EQ
A band-pass EQ with the option of adjusting the centre frequency around which the signal is altered.
http://www.youtube.com/watch?v=Gmrve23xRW8
Parametric EQ
A sweep EQ with the option of adjusting the ‘Q’ (also called resonance). This increases or decreases the range over which the frequency is cut or boosted either side of the centre frequency (increases or decreases the bandwidth)
• Low Q Factor: wider bandwidth
• High Q Factor: narrower bandwidth
Why is this important?
Why is this important?
Important for ALL portfolio
Use music technology keywords in your logbook to explain your choice of EQ and why.
Making sounds more realistic and fitting Task 1A better.
Synthesis
What is Synthesis?
How have you currently been creating your sounds for your instruments?
Synthesis
How are sounds created?
Synthesis
How are sounds created?
An oscillator creates a sound wave which can then be manipulated to design the sound you wish
Oscillators
Used to generate a raw repeating signal/wave
Different tyes of oscillators produce a variety of signals including sine, triangle, sawtooth, square and random noise waves
Sine Wave
• http://en.wikipedia.org/wiki/Sine_wave• No harmonics
Triangle Wave
• http://en.wikipedia.org/wiki/Triangle_wave• Only odd harmonics are sounded
Harmonic Numbers
Square Wave
http://en.wikipedia.org/wiki/Square_waveOnly uses odd harmonics – sounds similar to a triangle wave but slightly brighter in treble
Sawtooth Waves
• http://en.wikipedia.org/wiki/Sawtooth_wave• Uses all harmonics – sounds quite gritty
Why are these important to you?
Why are these important to you?
You can design your own sounds – very important!!
Start with a template and then adjust it or start from scratch if you wish!
What is the Sound Envelope?
What is the Sound Envelope?
ASDR
AttackSustainDecayRelease
Alter the sound of the audio signal over time, from the time it starts until the time there is no sound.
Sound Envelope• What
about a piano?
Sound Envelope (ASDR)
• Example of a piano: • What about a trumpet?
Sound Envelope (ASDR)
How to design your sound using the sound envelope
http://en.wikiaudio.org/ADSR_envelope
Filters
What do filters do?
Filters
What do filters do?Modify a signal by cutting/removing a specific frequency band. Changes the brightness of a sound. Filters use a cut-off frequency to define which frequencies are removed from the signal
Two main types: high-pass and low-pass
Types of filters
Low pass filter – removes frequencies higher than the cut-off frequency, allowing the lower frequencies to pass throughHigh pass filter – removed frequencies lower than the cut-off frequency, allowing the higher frequencies to pass through. Band pass filter – uses combination of both HPF and LPF to allow only frequencies near the cut-off to pass throughBand-elimination filter – uses both LPF and HPF to remove only frequencies near the cut off.Peaking filter – emphasizes frequencies near the cut-off frequency – also called resonance.
Sound Design and Synthesis
Start with an oscillator and work on the sound you likeAdjust the envelope (ASDR)Use EQ and filter to boost/cut the correct harmoniesUse reverb to complete the sound
Write it all up in your logbook – so important to show you can design your own sounds!!
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