CDS 389 Exam 4

What is the ball analogy used for in acoustics

Sound reflection can be visualized like a ball bouncing off a wall

What happens when a ball is thrown at a 90-degree angle to a wall

It bounces straight back along the perpendicular path

What is the incident path (Pi)

The angle/path of the incoming sound or ball toward the surface

What is the reflected path (Pr)

The path the sound or ball follows after bouncing off the surface

What is the geometric rule of reflection

The angle of reflection equals the angle of incidence relative to the perpendicular

How does sound reflection differ from a ball

Sound reflects in multiple directions simultaneously

Does the law of reflection apply to sound waves

Yes, the angle of reflected rays equals the angle of incident rays

What is an echo or reverberating wave

Reflected sound that persists after the original sound stops

What is reverberation time (RT)

The time required for sound to decrease by 60 dB

What are discrete echoes

Distinct repeated reflections like those in a canyon

What are flutter echoes

Ringing sounds caused by sound bouncing between parallel surfaces

Why do cathedrals have long reverberation times

Large spaces with hard surfaces reflect sound extensively

How does reverberation affect music vs speech

Enhances music but reduces speech intelligibility

How does audience presence affect RT

More people absorb sound, reducing reverberation time

Why is acoustics important for children

They rely on clear sound for learning and development

What are the two main types of learning in children

Direct learning and incidental learning

What are physiological effects of noise

Increased stress and elevated blood pressure

What are motivational effects of noise

Feelings of helplessness and giving up more easily

What are cognitive effects of noise

Reduced memory, attention, and ability to process sound

How does noise affect academic achievement

It lowers reading and language performance

What is phonemic awareness

Understanding that language is made of individual sounds

How do noise and reverberation affect phonemic awareness

They interfere with learning sound distinctions

What are the four sound-surface interactions

Absorption, diffusion, transmission, and reflection

What is absorption

Sound energy is taken in by a material

What is diffusion

Sound scatters in many directions

What is transmission

Sound passes through a material

What is reflection

Sound bounces off a surface

What surfaces cause strong reflection

Smooth and rigid surfaces

What surfaces promote diffusion

Irregular or specially designed surfaces

What are alpha coefficients

Measures of how much sound a material absorbs

What is attenuation

Reduction of sound measured between source and receiving spaces

What is the ideal classroom RT

Between 0.4 and 0.6 seconds

Why are many classrooms acoustically poor

They often have RT values above 1 second

How can classroom acoustics be improved

Add rugs, curtains, and acoustic materials

What is the vowel quadrilateral

A chart that maps vowel sounds based on tongue position

What are the two axes of the vowel quadrilateral

Tongue height and tongue backness

What vowel is /i/

A high front vowel

What vowel is /u/

A high back vowel

What vowel is /æ/

A low front vowel

What vowel is /ɑ/

A low back vowel

What are central vowels

Vowels produced with the tongue in a neutral position

What is schwa (/ə/)

The most common mid-central relaxed vowel

What is vowel roundedness

Lip rounding during vowel production

Which vowels are typically rounded

Back vowels

What is a nasal vowel

A vowel produced with airflow through the nose

Where is most speech energy concentrated

Below 8000 Hz, especially 500–4000 Hz

What is a waveform

A graph of air pressure changes over time

What does a waveform show above the zero line

Pressure greater than atmospheric pressure

What is a spectrum

A graph of energy as a function of frequency

What produces a spectrum

Fourier analysis of a waveform

What is a spectrogram

A graph of frequency over time

What does the vertical axis of a spectrogram represent

Frequency

What does the horizontal axis represent

Time

What indicates intensity on a spectrogram

Darkness or color intensity

What are formants

Resonant frequencies of the vocal tract

Which formants are most important

F1, F2, and F3

How are formants visualized

As peaks in spectra or bands in spectrograms

What distinguishes voiced phonemes

Presence of formants and vocal fold vibration

What are monophthongs

Vowels with stable formants

What are diphthongs

Vowels with changing formants

What are approximants

Semivowel sounds like w, l, r, y

What are nasals

Sounds with airflow through the nose like m, n, ng

What are fricatives

Sounds produced with turbulent airflow like s, f, z

What are plosives

Sounds with closure and burst release like p, t, b

What are affricates

Plosives followed by frication like ch and j

What do voiceless sounds lack

Formants

What do fricatives look like on spectrograms

Smooth clouds of energy

What do plosives look like on spectrograms

Bursts of energy after silence

What is the typical rate of speech

About 200 words per minute

What is coarticulation

Overlapping production of speech sounds

Why does coarticulation occur

To allow faster speech production

What are anticipatory movements

Preparing articulators for upcoming sounds

What is prenasalization

Nasal influence on nearby sounds like in "Freon"

What is assimilation

A sound changing to match a neighboring sound

How does rapid speech affect vowels

They are shortened or reduced

Why is coarticulation difficult for hearing-impaired listeners

Important speech cues are reduced or omitted