逸速く[ichihayaku] promptly
音速[onsoku] speed of sound
加速[kasoku] acceleration
加速運動[kasokuundou] accelerated motion
加速度[kasokudo] acceleration

快速[kaisoku] high speed
快速電車[kaisokudensha] high-speed train
角速度[kakusokudo] angular velocity
急速[kyuusoku] rapid (e.g. progress)
減速[gensoku] deceleration

ト音記号[toonkigou] G clef
ハ音記号[haonkigou] C clef
ヘ音記号[heonkigou] F clef
哀音[aion] sad voices
異音[ion] allophone

異句同音[ikudouon] in concert
異口同音に[ikudouonni] in one voice
一音節[ichionsetsu] monosyllable
一口同音[ikkudouon] reading in unison
羽音[haoto] sound of flapping wings (of a bird)