Working with Sounds Flashcards
What is a sound?
A propagated disturbance in the ambient pressure of a medium (air, water, etc.)
What is a signal?
A perceivable behaviour/feature that has evolved and has acquired the specific characteristic of conveying information about the signaller or the signaller’s environment
What is a cue?
Any feature or pattern produced by an organism without the purpose of communication, from which other organisms can obtain information
How does a microphone work?
It converts the variations in pressure created by a passing sound wave into electrical signals that mimic the rise and fall of sound pressure at the microphone
How do you measure frequency?
f= 1/T (in seconds)
Name two ways in which amplitude can be measured
1) peak to peak
2) RMS (root mean square)
Define amplitude
A measure of the average variation in pressure associated with the sound
Define the Fourier analysis
The analysis of a complex waveform expressed as a series of sinusoidal functions, the frequencies of which form a harmonic series
Fourier analysis
Any periodic function can be written as the _____________ with __________ and _________ values that can be measured
Any periodic function can be written as the SUM OF PURE SINE WAVES with FREQUENCY and AMPLITUDE values that can be measured.
What body part is the generator of sound?
The larynx (also known as the voice box)
What body parts does the larynx connect?
It connects the pharynx (throat) with the with the trachea (windpipe)
What is the epiglottis and how does it work?
It is a small flap at the top of the larynx that prevents food and water from entering the voice box. When you swallow, the larynx rises to meet the epiglottis to seal off the trachea.
What and where are the vocal cords?
They are two strips of tissue found in the larynx.
Is a higher or lower pitch created when the vocal cords are pulled tighter?
A higher pitch is created
What is the source-filter theory?
Speech can be seen as a source signal produced in the larynx and then filtered by the cavities of the vocal tract
What do ‘tubes’ in the vocal tract do?
They act as an acoustic resonator or filter
What do ‘valves’ in the vocal tract do?
1) Open and close the vocal tract to some tubes
2) Serve as sound source
Summarise what was discovered concerning fallow deer vocalisations
1) Body size affects Formant Frequencies
2) Dominant status affects fundamental frequency or pitch
What are formants?
They are broad peaks in the spectrum of a complex sound. They correspond to frequencies of vocalisations that are amplified by the vocal tract.
Define frequency
The number of crests of the sound wave that pass a given point in one unit of time
What is the fundamental frequency?
It is the lowest harmonic of a multi-harmonic sound. It is produced by the vibration of a sound-producing object over its full length, while higher harmonics correspond to modes of vibration in a fraction of the length
What is a harmonic?
It is a sound wave whose frequency is an integer multiple of a reference frequency, so if the reference frequency is f then the harmonics will have frequencies 2f, 3f, 4f etc. The reference frequency is called the fundamental frequency
Define pitch
the quality of a sound governed by the rate of vibrations producing it; the degree of highness or lowness of a tone.
For pure tones (tones that can be described as a single sine wave), the pitch tends to follow the actual frequency of the sound quite closely.
