acoustics 2 - the brain - complex wave forms 2

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 Acoustics  acoustics n. 1. (used with a sing. verb) 

The scientific study of sound, especially of its generation, transmission, and reception. 

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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.

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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?

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Is there sound in space?

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  Apply the missing labels:

Tympanic Membrane Pinna Ossicles Cochlea

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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?

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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.