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8/20/2019 Acoustics 2 - The Brain - Complex Wave Forms 2
http://slidepdf.com/reader/full/acoustics-2-the-brain-complex-wave-forms-2 1/19
Acoustics acoustics n. 1. (used with a sing. verb)
The scientific study of sound, especially of its generation, transmission, and reception.
8/20/2019 Acoustics 2 - The Brain - Complex Wave Forms 2
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Envelope Experiments
Open Logic and create a software instrument track.
Find a suitable sound and record in one note.
Bounce and merge into an ‘audio file’.
Manipulate its envelope using ‘automation’ (remember press
A key) now try to create a quicker/longer attack or release.
Create screengrabs (remember: cmd sft 4) of the waveforms
before and after you have manipulated them.
Repeat the process.
8/20/2019 Acoustics 2 - The Brain - Complex Wave Forms 2
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Human Hearing
Are you listening? How do we hear?
The Ear
Psychoacoustics
Envelope
Apply the principles of a waveform’s ‘Envelope’ to‘shape’ a sound.
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What is sound?
8/20/2019 Acoustics 2 - The Brain - Complex Wave Forms 2
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Is there sound in space?
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Apply the missing labels:
Tympanic Membrane Pinna Ossicles Cochlea
8/20/2019 Acoustics 2 - The Brain - Complex Wave Forms 2
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The Ear
We need ears to hear, but why do we need two of them?
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Psychoacoustics
The study of sound perception
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Auditory Illusions
Much like visual illusions the
brain is capable of
performing auditory illusions
– for example, the gliss ndo
illusion.
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Sound Localisation
Very slight differences in intensity and
timing allow us to determine where a sound
has come from.
The position of our ears means we are better
at locating sounds on a horizontal scale.
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Auditory MaskingThe brain can appear to
cancel out a sound when
something louder comes
along.
For example, when you
are at a bus stop and alorry goes past you ‘stop
hearing’ the conversation.
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The Cocktail Party Effect
.
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Psychoacoustics
Sound Localisation
Auditory Masking
Cocktail Party Effect
Another phenomenon is the Doppler Effect (but note this
happens outside of the brain).
Why must all of these must be considered when mixing and
recording music?
8/20/2019 Acoustics 2 - The Brain - Complex Wave Forms 2
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Many musical instruments can generate the same frequencies. So
how can we tell them apart?
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Timbre
The shape and material of the instrument will effect
the frequencies it produces (most notably the
harmonics).
The ‘envelope’ of an instrument will also allow us to
differentiate one instrument from another.
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Envelope is a crucial characteristic of a ‘waveform’ –
ADSR (attack, decay, sustain, release)
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Complex waveform and envelope of a single snare drum.
Waveform of a vocal line.
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Equalisation (EQ)
What is an ‘equaliser’?
A device, circuit or piece of software that lets us control the relative
amplitude of various frequencies within the audible bandwidth.
What does it allow us to do?
- Correct specific problems in a recorded sound (possibly to restore
a sound to its natural tone).
- Overcome deficiencies in the frequency response of a mic or in the
sound of an instrument.
- Allow contrasting sounds from several instruments or recorded tracks
to better blend together in a mix.- Alter a sound purely for musical or creative reasons.