Vocalisation As A Welfare Indicator Flashcards
Define vocalisation
Vocalisation = the active generation of sound with specific organs
Define sounds
Sounds = pressure wave traveling through a medium created by a vibrating object
Basically pressure waves in sound are a series of molecules squeezed together (compression) and pulled apart (rarefaction) which causes molecules next to them to do the same thing sending the motions to the next molecules and so on
What happens when sound hits the eardrum?
Sound will eventually hit the eardrum causing the inner workings of the ear to vibrate like the molecules
Why is sound ideal for communication with conspecifics at a distance?
Sound is ideal for communication with conspecifics at a distance since it carries and is relatively insensitive to objects in its way
Sound is good for animals to communicate since it travels far and through many different mediums
What is amplitude?
Amplitude is the size of the vibration
What does amplitude show?
How much energy is in the sound
What does amplitude determine?
Amplitude determines the volume of the sound
What is frequency?
Frequency is the speed of vibrations
What is frequency a measure of?
Frequency is a measure of how many compressions and rarefactions are in a given period of time
What are the units of frequency?
Hertz or Hz
Define Hertz
How many wavelengths (compression and rarefaction cycles) occur in 1 second
What does frequency determine?
Frequency determines pitch
The higher the frequency the more wavelengths occur
The higher the frequency the higher the pitch
Why is biological sound not pure sine waves?
When objects vibrate they can cause either secondary vibrations or harmonics
What are secondary vibrations and harmonics?
Secondary vibrations and harmonics produced will be exact multiples of the first sound or the lowest frequency of sound
An example is that the first harmonic (the original sound) could be 50Hz followed by a second harmonic at 100Hz which is followed by a third harmonic at 150Hz and so on
The copies are multiplied in frequency compared to the copy/original they’re being duplicated from
It’s like if the first/fundamental sound was the smallest russian doll and the second vibrations/harmonics are all the other dolls getting bigger in a set order/multiple of the previous dolls size
In source-filter theory what body parts make up the source?
Lungs
Trachea
Larynx
How is sound generated in the source in source-filter theory?
To generate sound first you’d exhale air from the Lund and trachea
The animal can control the air flow, to some extent, so it can control the speed and force at which it leaves the body
The air will travel up the trachea and into the larynx
As the air passes through the larynx it will vibrate vocal folds in the larynx
The vibrations generated by the vocal folds of the larynx will generate the fundamental frequencies and the harmonics
In source-filter theory what is the job of the lungs and trachea?
Generate and control the air flow
The lungs and trachea are used for respiration
In source-filter theory what is the job of the larynx and vocals folds?
Phonation
Define phonation
The production or utterance of speech sounds
In source-filter theory where will the sound travel through once it exits the larynx (source)?
After passing through the larynx the air will pass through the vocal tract
The vocal tract is all the structures between the larynx and the opening of the mouth
In source-filter theory what happens to the sound when it is in the vocal tract?
Within the vocal tract the sound will be filtered by dampening some parts of the sound and amplifying other parts of the sound
What is the dampening and amplifying of various parts of the sound in the vocal tract know as?
Resonance
Through the use of what do humans further manipulate the sound before it leaves the mouth to produce language specific sounds?
Tongues Lips Teeth Jaw Hard and soft palate
What are the lungs and trachea responsible for in terms of the sound?
Amplitude
Volume
Duration of the sound
Fundamental frequency
Respiration
What is the role of the larynx in vocal production?
The larynx is then responsible for producing or modifying the fundamental frequencies and the harmonics according to the vibration of these structures
The anatomy and physiology of the structures in the larynx affect the sound
The vocal folds length, thickness and tension will alter the sound generated
The characteristics of the vocal tract determines the filtering process, but what characteristics alter the filtering process?
Shape
Length
Tension
How many kinds of cavities are in the tract
What does the filtering process in the source-filter theory produce?
Formants
Define formants
Formants = a range of peak resonance frequencies that then radiates from the mouth
Formants are frequencies within the spectrum that carry the most energy within that vocalisation
Resonance = the dampening and amplifying of various parts of the sound
How are fundamental frequencies created?
The source sound is generated by respired air vibrating vocal folds in the larynx to produce a fundamental frequency
What is the fundamental frequency commonly known as?
F0
How are formants produced?
The sound is then filtered in the vocal tract to produce formants/peak resonances
What are formants usually termed?
F1
F2
F3
F4
How far apart is each formant from each other?
Each formant is roughly 1000Hz apart
What are the 2 hypothesises about how you can use vocalisation as a welfare indicator?
1) That emotions/moods in animals can initialise vocalisation, and so drive vocalisation creation
2) That emotions or mode can modulate and change features of the vocalisation according to the animals mental state
Explain the theory that “emotions/mood may initialise vocalisation”
Emotions/mood may initiate vocalisation
This hypothesis works on the assumption that vocalisations are outward expressions of an internal state which have partly evolved to indicate some type of need from the vocalising individual
This means that evolution has selected genes that are associated with auditory communication to be passed onto the next generation due to vocalisations increasing an animals fitness
Since it’s believed that vocalisations have been selected to demonstrate an animals needs vocalisation can be argued to be able to:
- indicate some animal states
- responses from individuals hearing the vocalisation can be assumed to be innate
Individuals who hear the vocalisation can be assumed to have responses genetically programmed into them
This means that we can interpret the communicative meaning of the call and the emotion of the sender by looking at the:
- response of the receiver in terms of the communicative meaning
- context of the call
When using the “emotions/mood initialise vocalisation” theory what does this mean for vocalisation as a welfare indicator?
Emotions/mood initialise vocalisation
However using vocalisations as a welfare indicator under this hypothesis means we’d assume we understand the context and meaning of that call in absence of a conspecific receiver
When looking at the “emotions/mood initialise vocalisation” theory what do some researchers argue about motivation?
Some researchers argue that motivation refers to the likelihood an animal will perform a behaviour and not directly refer to the animals emotional state
However, this does still imply that vocalisation motivations are due to an underlying emotion
Give an example of vocalisations also being elicited by pharmacological stimulants that stimulate neural circuits involved in mood and emotions in animals including humans
In 2000 Parrot et al saw that corticotropin-releasing hormone in test animals caused vocalisation alterations
What supporting evidence is there for the context aspect of the “emotions/mood initialise vocalisation” theory?
In support of the context aspect of the theory that emotions initialise vocalisation, it is known that a number of vocalisations across species have been recorded to occur in specific contexts
Often these are signals that require a response
The presence, absence or prevalence of the vocalisation could indicate specific states in the senders within a population
What is a problem with the “emotions/mood initialise vocalisation” theory?
One of the main problems with using vocalisations as a welfare indicator is that using verbal descriptions of vocalisations can be ambiguous and need to be defined by acoustic characteristics
This means that describing a vocalisation verbally may not be specific enough to distinguish it from other similar vocalisations and so we need particular characteristics of the sound to identify it properly
Examples of characteristics of vocalisation are duration and frequency.
Explain the theory that “emotions and mode may modulate vocalisations”
Emotions and mode may modulate vocalisations
The vocalisation itself may not indicate welfare but changes in call features and how it’s made could indicate sender motivational states
What supporting evidence is there for the theory that”emotions and mode may modulate vocalisations”?
Emotions and mode may modulate vocalisations
This theory is supported by the fact that in humans emotions induce changes in the nervous system leading to changes in:
- tension and action of muscles used for voice production
- respiration and saliva production
What alters “tension and action of muscles used for voice production” in the emotions and mode may modulate vocalisations theory?
This is done primarily done via the somatic nervous system
What alters “ respiration and saliva production” in the emotions and mode may modulate vocalisations theory?
This is done via the autonomic nervous system
How does saliva production alter vocalisations?
The saliva production alterations can change resonance in the vocal tract leading to alterations in the formant frequencies
Decreases in saliva production result in higher formant frequencies
What can subtle changes in a specific vocalisation and the characteristics of the vocalisation indicate in the “emotions and mode may modulate vocalisations” theory?
More subtle changes in a specific vocalisation and the characteristics of the vocalisation may indicate changes in mood
What did Morton 1977 create?
The motivational structural rules concept
What did Morton 1977’s motivational structural rules concept predict?
1) Low frequency calls will be made in hostile contexts
This is because in hostile contexts the animal may mimick a larger animal to seem more threatening
2) High tonal sounds in fear or appeasing contexts
This is because in fear/appeasing contexts the animal may mimick an infant so they’re more likely to be forgiven or left alone
How did Briefer 2012 make the motivational structural rules concept more detailed?
Briefer 2012 predicted that:
1 - during agonistic contexts there’d be calls with:
- long durations
- low frequencies
- wide frequency ranges
- little frequency modulation
Agonistic = any social behaviour related to fighting
2 - during non-aggressive or fear-eliciting contexts there'd be vocalisations with:
- short durations
- high frequencies
- more frequency modulation
- tonal
- no special noise
- the harmonics structure is not clear
How does Briefer 2012 argue that we can measure increases in arousal?
In 2012 Briefer looked into the literature and argued that we can measure increases in arousal
Increases in arousal are typically reflected in longer, louder and harsher vocalisations, and are produced at faster rates with higher and more variable frequencies
Briefer 2012 also argues that we can look at the changes in numbers of elements in complex vocalisations
We can look for:
- hoarseness/breathiness
- jitters
- cycle to cycle frequency variations
- time of peak frequency
- noise
This argument needs further evidence to support it
However these parameters are based on the ones recorded for humans and are associated with the hypothesis that emotions and mode may modulate vocalisations
What does Briefer 2012 argue about vocalisation and valence?
In 2012 Briefer says that vocalisation as a valence indicator has been less studied
Humans tend to find it easier to identify contacts in which negative state vocalisations occur
This could be due to negative state vocalisations indicating urgency and immediate needs which may be more common and easier to identify
Due to this it is difficult to find situations of similar arousal but differing in valence
Briefer 2012 argued that compared to negative vocalisations, vocalisations produced in positive situations are shorter but the fundamental frequency varied
Briefer 2012 suggests that we need to investigate some of the more complex and subtle characteristics of sounds/vocalisation to understand vocalisation valence
What has been suggested about hearing/receiving a vocalisation?
It has been suggested that receiving/hearing a vocalisation may modulate the emotional state of the receiver
What has been suggested about human interpretation of vocalisations?
It has been suggested that humans are pretty good at determining emotional states associated with vocalisations
What are the 4 advantages of vocalisations as a welfare indicator?
1) We can assume that vocalisations evolved to change another’s behaviour since they signal a want or need
2) In terms of basic parameters vocalisations are easy to record
3) There’s some evidence of homology with human vocalisation production
4) Evidence based off human vocalisation variations and their meanings can help create testable hypothesises in animals
What are the 6 disadvantages of using vocalisations as a welfare indicator?
1) Using vocalisations as a welfare indicator may be more relevant to use on social species if the vocalisation just signals a want or need
2) Complex equipment is required for:
- complex vocal analysis
- vocalisations outside of human hearing ranges
3) Vocalisations may be specific to a specific context
4) To date we have more information on arousal but not as much information on valence
5) Vocalisations can vary between different strains of the same species
6) In groups it can be hard to locate the animal that made those calls
What are the 3 assumptions and caveats with using vocalisations as a welfare indicator?
1) With vocalisations it’s important to understand functional significance of the calls to understand motivational and emotional significance
2) With vocalisations we need to assume that the animal is honestly signalling a want or need
3) We have to assume that there are no other factors that can contribute to changes in vocalisation which we may say are due to emotion but are actually due to another cause
- We have to assume that all vocalisation changes are due to changes in emotional states
