Question: what does ghz measure in relation to sound
[{'answer': 'frequency', 'provenance': [{'wikipedia_id': '14121', 'title': 'Hertz', 'start_paragraph_id': 1, 'start_character': 46, 'end_paragraph_id': 1, 'end_character': 55, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '14121', 'title': 'Hertz', 'start_paragraph_id': 12, 'start_character': 0, 'end_paragraph_id': 12, 'end_character': 536, 'bleu_score': 0.9776501033621461, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 454818932324203332}, 'section': 'Section::::Applications.:Vibration.\n'}]}]