Reby et al. (2005)

Question 1

Aim

Answer 1

• to see if formant frequencies function to provide cues to size in red deer
• too see if red deer stags adjust their agnostic behaviour and own responsive vocalisations in reaction to formant frequencies in a simulated opponents roar

Question 2

Prediction

Answer 2

• if hear an opponent with a lower formant frequency, then males shall respond with a lower formant frequency and also change behaviour

Question 3

Design

Answer 3

• resynthesised roars of mature stags between 8-9 in Scotland which current stages had not heard before
• duration of 6-7 seconds
• formant frequency and spacing was recorded and estimation of apparent vocal tract length
  then resynthesised, keeping F0, harmonics, intensity and duration same, but changing formant frequency - therefore altering the apparent vocal tract length to make seem larger
• everything kept same apart from vocal tract length perception
• played paired playbacks every 2 days, about 100m away from a subject, or 50-100m away
• trial consisted of two presentations - 3 roar stimulus
• also video recorded responses 2 mins before and 5 mins after
• behaviour measured using: duration of attention, no. of roars and harsh roars

Question 4

Results

Answer 4

• 19 pairs of playbacks
• subjects showed greater attention to the stimuli with formants representing a medium size adult compared to a subadult, and to those representing a large than small adult
• also delivered more common roars to medium adult then sub adults
• BUT NOT more common roars to a large vs. small
• average formant spacing was lower in first roar for medium adult compared to medium subadult
• VTLs 4.3cm longer to adult than subadult
• formants in roars gien to a large adult stimuli had spacings on average 12Hz lower than in those given to a small adult

Question 5

Issues

Answer 5

• video recording a distance away, so hard to record
• sound signals may have had disturbances such as wind
• synthesised so not like real voices

Question 6

Follow up

Answer 6

existing follow up:

- playing resynthesised roars to female receivers, seeing if they pay more attention behaviourally