ICT role in 21st century education and it's challenges.
Speech acoustics
1. Speech acoustics Objectives: Describe relative frequency and intensity of phonemes by voice, manner, and formant frequency. Describe various phonemic cues. Describe speech constraints.
2. Average speech intensity ~65 dB SPL (~45 dB HL) 30 dB range Any vowel has more power than any consonant
3. Average speech frequency ~50 – 10,000 Hz Most energy below 1000 Hz Fundamental frequency Men: 100 Hz Women: 200 Hz Children: 300 Hz Crying babies: 500 Hz Cues for talker identity
9. Phonemic cues - Stops Closure Voiceless stops – silent period Voiced stops – low level energy Burst Wide-band energy ~40 msec Greater intensity for voiceless stops Frequency depends on place Formant transition First formant always rising Second formant transition depends on place
10. Phonemic cues - Stops Voice easier to detect than place For voiced stops Voice-onset time is earlier Energy present at fundamental frequency Burst energy is lower in amplitude Vowels are longer in duration before voiced final stops (“eyes” v. “ice”)
11. Phonemic cues - Nasals Always voiced Continuant Nasal resonance highest for /m/ lowest for /n/ Second formant (frequency and transition) gives place information
12. Phonemic cues - Fricatives Hissing quality Voiced fricatives Periodic Lower frequency Lower amplitude Greater overall energy (from fundamental) Sibilants (s, z, sh, zh) Higher amplitude than other fricatives
13. -f- -θ- -s- -S-
14. Suprasegmental cues Stress changes in fundamental frequency, intensity, duration Intonation changes in fundamental frequency, pitch pattern expresses attitudes, feeling, meaning (command, request, statement) Duration variations in speech sounds due to context of other sounds
15. Speech constraints Syntactic S = NP (Aux) VP NP = (Det) (AP) N (PP) “the naughty boy in the daycare…” VP = V (NP) (PP) (Adv) “…took the toy away brusquely”
16. Speech constraints Syntactic S = NP (Aux) VP NP = (Det) (AP) N (PP) “the naughty boy in the daycare…” VP = V (NP) (PP) (Adv) “…took the toy away brusquely”
17. Speech constraints Syntactic The question “What should you eat” Answer is a noun phrase The question “How should you eat” Answer is an adverbial phrase
18. Speech constraints Semantic Words in a sentence are related meaningfully “Plug the mouse into the computer” Situational Conversation usually refers to the context of the environment “I like that oat!” Mall vs. Farm
19. Overlapping cues help protect the signal from noise Speech predictability helps protect the signal from noise Noise can come from the speaker (poor intelligibility, etc) the environment (distractions, etc) the listener (ESL, etc)
20. Effects of hearing loss on speech perception Objectives: Describe speech characteristics that are lost and that are preserved for hearing losses of various degree, type and configuration.
43. Severe Access to only loudest components of speech Speech production High airflow rate Speech initiation at low lung volumes Poor velar control (nasality) High fundamental frequency Slow speech rate
44. Moderate Access to louder half of speech, or to loud speech Speech production Substitutions and distortions Errors in affricate, fricatives and blends
45. Slight to Mild Access to all but the quietest components of speech Speech production Fewer distortions/substitutions Good intelligibility