Question: what are the 3 properties of a medium that effect sound
[{'answer': 'pressure', 'provenance': [{'wikipedia_id': '18994087', 'title': 'Sound', 'start_paragraph_id': 1, 'start_character': 81, 'end_paragraph_id': 1, 'end_character': 89, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'answer': 'velocity', 'provenance': [{'wikipedia_id': '18994087', 'title': 'Sound', 'start_paragraph_id': 7, 'start_character': 90, 'end_paragraph_id': 7, 'end_character': 98, 'bleu_score': 1.0, 'section': 'Section::::Definition.\n'}]}, {'answer': 'displacement', 'provenance': [{'wikipedia_id': '18994087', 'title': 'Sound', 'start_paragraph_id': 7, 'start_character': 67, 'end_paragraph_id': 7, 'end_character': 79, 'bleu_score': 1.0, 'section': 'Section::::Definition.\n'}]}, {'provenance': [{'wikipedia_id': '18994087', 'title': 'Sound', 'start_paragraph_id': 9, 'start_character': 0, 'end_paragraph_id': 9, 'end_character': 1070, 'bleu_score': 0.988919240064389, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 1712467653958751728}, 'section': 'Section::::Physics of sound.\n'}]}]