The Collaborative International Dictionary of English v.0.48:

Sonority \So*nor"i*ty\, n. [L. sonoritas.]
   The quality or state of being sonorous; sonorousness.
   [1913 Webster]

WordNet (r) 3.0 (2006):

sonority
    n 1: having the character of a loud deep sound; the quality of
         being resonant [syn: plangency, resonance,
         reverberance, ringing, sonorousness, sonority,
         vibrancy]

Moby Thesaurus II by Grady Ward, 1.0:

87 Moby Thesaurus words for "sonority":
   allophone, alveolar, apico-alveolar, apico-dental, articulation,
   aspiration, assimilation, bassness, bilabial, cacuminal, cerebral,
   check, consonant, continuant, crescendo, deepness, dental,
   diphthong, dissimilation, epenthetic vowel, explosive, fullness,
   glide, glottal, glottalization, guttural, hollowness, intensity,
   labial, labialization, labiodental, labiovelar, laryngeal, lateral,
   lingual, liquid, loudishness, loudness, lowness,
   manner of articulation, mellowness, modification, monophthong,
   morphophoneme, mute, nasal, occlusive, palatal, parasitic vowel,
   peak, pharyngeal, pharyngealization, phone, phoneme, plangency,
   plosive, prothetic vowel, resonance, retroflex, richness,
   segmental phoneme, semivowel, sonant, sonorousness, speech sound,
   stop, surd, surge, surge of sound, swell, swelling,
   syllabic nucleus, syllabic peak, syllable, transition sound,
   triphthong, velar, vibrancy, vocable, vocalic, vocoid, voice,
   voiced sound, voiceless sound, voicing, volume, vowel