https://www.youtube.com/watch?v=vyea8Ph9BOM&list=PL8dPuuaLjXtP5mp25nStsuDzk2blncJDW&index=9&ab_channel=CrashCourse

Physical Sounds

Acoustics : the physical characteristic of sounds

• longitudinal wave (縱波) / transverse wave (橫波, perpendicular = 垂直)

• tuning fork : consists of only ONE frequency (pure tone)

  elasticity : the restoring force (音叉恢復的彈力)

  inertia : (慣性)

• periodic ⇒ complex (像樂器那樣疊合) ⇒ aperiodic (例如噪音)

<aside> 🔊 Essential constituents : source of energy, source of vibration, and medium.

</aside>

Spectrogram

A graphic representation of sounds in terms of their component frequencies, in which...

1. time is shown on the horizontal axis,
2. frequency on the vertical axis, and
3. the intencity of each frequency at each moment in time by the darkness of the mark.

• Formants : (spectral) peaks of pressure, which are characterized

• different vowels can be chararterized by different formant profiles

• timbre : 音色 !

• octave & semitones : for each key,

  $$ F_n\times2^\frac{1}{12} = F_{n+1} $$

Speech Sounds

Places of Articulation (發音部位)